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Each year, the popularity of houseplants increases and few people can resist having some flowering or foliage plants to transform their house into a home. Apart from creating color and vibrancy, houseplants have a therapeutic quality: they are alive and need regular, careful attention, generating rapport with people throughout the year.

Given the fast pace of life today, and the pressure it creates in our lives, the restful atmosphere that can be engendered by houseplants is essential. The range of houseplants is wide, including flowering and foliage types, as well as indoor ferns, bromeliads, cacti and other succulents, palms and cycads, bulbs, and insectivorous plants. All have different needs, and whether your home is a bungalow or a high-rise apartment, there are plants that will thrive in it. Some are native to tropical and subtropical regions, while others are hardy enough to grow outdoors in temperate zones but can also be grown indoors when young and in a pot.

In the directory of houseplants in Part Two, you will find detailed information about each plant’s needs, from warmth and light throughout the year, to watering and feeding, as well as how to increase plants.

Growing plants indoors is an all-embracing hobby. While some plants happily thrive on windowsills, others develop into large, eye-catching features that live for so long they become as much a part of a home as a dog or cat. Indeed, it is not unknown for long-lived plants to be given pet names!

Looking after houseplants requires skill and dedication because they are such a disparate group, ranging from plants native to deserts to those with a jungle heritage. Some have a limited life span, while others continue their display throughout the year.

Buying Houseplants

Choosing and buying plants for the home needs care if they are to create spectacular displays that last a long time. There are several sources of houseplants, including garden centers, plant nurseries, florists, and main-street shops. Each has advantages, but whatever the source, it is essential to inspect the plant before buying it.

Always check for signs of a healthy plant before you buy from a nursery or garden center.

10 Tips for Buying Houseplants

1 Always buy from a reputable source. A cheap purchase may prove expensive if the plant dies a few weeks later.

2 Never buy a houseplant that is displayed outside a shop; in winter, such plants become chilled, while in summer they are exposed to direct, often intense sunlight. Flowering plants suffer most from excessive cold or heat.

3 Avoid buying plants that show signs of pests and diseases. They are never a success and may infect houseplants already in your home. Check above and under leaves, as well as on flowers and stems.

4 Never buy a plant with masses of roots growing out of drainage holes in the pot’s base. This indicates that the plant has been neglected and needs repotting. Additionally, growth may have been retarded.

5 When buying flowering plants, ensure there are plenty of flower buds waiting to open. Avoid plants that are in full flower—their display will be short-lived.

6 Do not buy plants that are wilting; this indicates neglect from which the plant may not recover.

7 Check that the compost is evenly moist. Plants can wilt through excessive watering as well as from being kept dry.

8 Avoid buying plants with green mold on the compost’s surface; it indicates neglect and excessive watering.

9 Only buy clearly labeled plants, as this indicates a reputable source.

10 Do not buy large plants that are growing in very small pots, or small plants growing in very large pots. Apart from an imbalance of size and a lack of stability, large plants in small pots need frequent watering, while it is difficult to keep the moisture content of the compost of small plants in large pots even and not too wet.

This plant needs to be repotted.

Moldy compost indicates excessive watering.

The size of plants and their pots should be in balance.

Getting Your Plant Home

The first stage in ensuring a good display is to get your plant home safely. Here are some hints.

 Either make buying a plant a separate occasion, or the last stop on a shopping expedition.

 In winter, do not put plants in a cold car boot or trunk. Also avoid these areas in summer as they quickly become excessively hot.

 Avoid putting plants in either cold or hot drafts near open windows.

 Many plant nurseries and garden centers sell houseplants totally covered in a paper wrapper or plastic sleeve to protect them from knocks and cold winds.

 If possible, leave young children and lively dogs at home when shopping for plants!

Protective sleeve

Acclimatizing Plants to Your Home

As soon as possible, get your plants home and remove the wrappings. If left covered, stems and foliage may become distorted. Here are some ideas on how to establish plants indoors.

 Check that the compost is lightly moist, but not saturated and waterlogged.

 Initially, place your plant in a cool or moderately warm room, out of direct and strong sunlight, and away from cold or hot drafts. After a few days, position it in the location with its desired temperature and light intensity (see conditions recommended for individual plants in Part Two).

 If the plant is flowering, avoid bumping it, which may cause buds to fall off.

 If you suspect your plant is contaminated with pests and diseases, isolate and treat it with an insecticide or fungicide.

Pots, Saucers, and Cachepots

These are fundamental to growing houseplants. Traditionally, pots were made of clay, and these still are considered ideal for plants, though plastic pots have gained increasing popularity. Both have advantages and disadvantages.

Clay Pots

 are heavier than plastic pots, creating a firm base for large plants

 have a porous nature that allows damaging salts from fertilizers to escape—a bonus if plants are excessively fed

 encourage the compost to remain cool in summer and warm in winter

 have a natural color that harmonizes with all plants

 absorb moisture readily, so must be immersed in clean water for a few hours before use

 usually break when dropped on a hard surface

 are more difficult to clean than plastic pots when very dirty

 are more expensive than plastic pots

 are usually used in conjunction with loam-based composts

Plastic pots and clay pots

Plastic Pots

 are light and easy to handle

 are not porous, so plants need less frequent watering than when in clay pots

 are available in a wide color range

 do not break easily when dropped, although cold temperatures make them brittle

 are cheaper than clay pots

 are usually used in conjunction with soil-less composts, such as those based on peat

Saucers

These are placed under pots to prevent water draining from the compost and trickling onto decorative surfaces. Most are now made of plastic, in a wide range of colors and sizes. Choose a size fractionally larger than the pot’s base.

Saucers

Cachepots

Also known as cover pots and potholders, cachepots are decorative, usually complementing the decor and a plant’s flowers and leaves. Some are plain colors, while others are patterned; most are round, others square. The growing pot is placed inside the cachepot. The rim of the growing pot must be level or slightly below that of the cachepot.

The practical difficulty with cachepots is that it is easy to over-water a plant unwittingly. Water remains in the pot’s base, eventually causing roots to decay. About 10 minutes after watering a plant, remove the plant, together with its growing pot, and tip away water remaining in the cachepot’s base.

Cachepot

Range of Pot Sizes

Pots are measured by the width across the rim, ranging from 2in (5cm) to about 15in (38cm). For home gardeners who buy a plant and discard it when it ages and becomes unsightly, only a few spare pots are needed, but enthusiastic houseplant growers will need a few more so plants can be repotted into larger pots. Ideally, when repotting a plant, especially when small, a pot of only about 1in (25mm) larger than the existing one is about right. However, this would require a wide assortment of pots, so a range of pots, each about 2in (5cm) larger than the next, is usually selected.

Match the cachepot color to the colors of the plant.

Potting Composts

Garden soil is unsuitable for growing plants in pots indoors; it has a variable nature and may contain pests, diseases, and weed seeds. Buy special compost mixtures.

Traditionally, loam-based composts were—and still are—used. These are formed of partially sterilized loam, sharp sand (also known as concreting sand), and peat, with the addition of fertilizers and ground limestone or chalk. Never use soft sand (or builders’ sand), which compacts when wet and does not allow air to penetrate the compost.

Difficulties in obtaining good loam encouraged the creation of composts without loam, known as soil-less composts. They are formed mainly of mixtures based on granulated peat and are uniform, as well as lighter and cleaner to use than loam-based types. Both have advantages and disadvantages.

Understanding the Term “Compost”

The term compost is often confusing and can be interpreted in several ways. Here are a few terms you might encounter.

Potting composts are free from pests and diseases and are specially formulated to encourage the active growth of roots, providing suitable plant foods, air, and moisture. All references in this book to “compost” are solely to potting composts.

Loam-based composts are primarily based on partially sterilized loam.

Soil-less composts, often known as soil-less compost mixes, are mainly formed of granulated peat and, for that reason, are frequently called peat-based composts.

Garden compost is derived from organic waste material from gardens and kitchens that has been placed in a compost heap or bin and allowed to decay. Eventually, this material, when fully decayed and friable, is either dug into soil to improved its structure and fertility, or spread on the surface of bare soil or around (but not touching) established plants to increase soil fertility and inhibit the growth of weeds (known as mulching). The decaying process can take up to a year and is influenced by temperature, bacteria activity, air, and moisture. This material is not a suitable compost in which to grow house plants.

Garden soil (sometimes just referred to as potting soil) is not suitable for house plants as it has a variable nature and may contain an imbalance of clay, silt, and loam as well as being contaminated by pests and diseases. It may also be excessively acidic or alkaline and nutritionally imbalanced.

Loam-Based Composts

 are heavier than peat-based types, giving greater stability to plants, especially those with a mass of foliage

 are unlikely to dry out as fast or as completely as peat-based types

 have a larger reserve of minor and trace plant foods than peat-based types

 are suitable for most houseplants

Peat-Based Composts

 are more uniform than loam-based composts

 are easily carried home in bags and stored (seal the bag’s top by folding it over)

 are light and easy to use

 dry out more quickly than loam-based types and are more difficult to remoisten if watering is neglected

 require plants to be fed at an earlier stage in their growth than with loam-based composts

Other Types of Compost

The continued removal of peat from peat beds has destroyed the environments of many animals, birds, insects and native plants, so there has been pressure to use more environmentally friendly composts. These are formed of several different materials, some of which are also used as additives to other composts to help retain moisture. Look for peat-free composts when buying soil-less types.

Specialist Composts

The range of plants grown indoors is wide, and it is clear that just one type of compost will not suit them all. Most flowering and foliage houseplants grow well in loam-based or peat-based composts (but do not change the type of compost when repotting a plant). Specialist plants, such as cacti and bromeliads, need types better suited to their specific needs. These can be purchased from garden centers and specialist outlets.

For healthy plants, sunlight and the correct ambient temperature for the species are vital.

Light and Warmth

Sunlight is essential for plants to grow, and it must be in balance with temperature. In the wild, these are usually in harmony: as light intensity rises, so does the temperature. However, in homes—especially in winter—the temperature may be high but the light intensity low. Adjustments can be made to the temperature, but the temperature is usually selected to suit people rather than plants.

 The intensity of light varies from one season to another, as well as throughout the day. In the plant directory in Part Two, the amount of light needed in winter and summer is indicated for each plant.

 Light intensity rapidly decreases as distance from a window increases. The amount of illumination at 8ft (2.4m) from a window is 5–10% of that of the light reaching a windowsill.

 Temperatures vary throughout the year; those to suit plants in winter and summer are indicated in the individual listings in Part Two.

 In general, flowering houseplants need more light than those grown mainly for their foliage, while cacti require good light at all times.

 Plants should not be moved suddenly from dull light to strong light.

 Keep windows clean, especially during winter when light intensity is low. In summer, sheer curtains help to diffuse strong sunlight.

 Rooms decorated in light colors reflect more light than dark shades—a major benefit in winter.

 Leaves and stems soon turn toward the light source, causing distortion. Counteract this by turning plants a quarter of a turn every few days.

 In winter, plants close to windows may receive good light but be exposed to drafts from ill-fitting window frames, causing flower buds to fall off.

The Need for Water

Like all living things, plants are mainly formed of water and, if deprived of it, eventually die. Some, such as cacti and other succulents, have water-storage mechanisms in their leaves and stems, but most plants need a regular supply. The amount required varies through the year and is influenced by light intensity and temperature.

Water the compost and allow to drain.

Watering a Houseplant

There are several ways to water a houseplant. The usual method is “over the rim.” This involves using an indoor watering can to pour water into the space between the top of the compost and the rim of the pot. Allow water to seep into the compost and drain through it into a saucer. After about 10 minutes, tip away excess water from the saucer.

Alternatively, where it is essential not to moisten the leaves (especially those that are hairy and soft, such as saintpaulias and Episcia cupreata), stand the pot in a bowl shallowly filled with water. When moisture rises to the compost’s surface, remove the potted plant and allow excess water to drain.

How to Judge If a Plant Needs Water

More houseplants die each year from too little or too much water than for any other reason. Judging when to water is a skill derived from experience, although in recent years several specialized pieces of equipment have helped to take the guesswork out of this task. Year-round water requirements for individual types are indicated in the plant directory in Part Two. Here are several practical ways to judge if a plant needs water.

1 A handy “when to water” guide is that water is needed if the surface of compost in a pot has a light color. Conversely, when the compost is dark, it is probably sufficiently moist.

2 Place the clay pot on a flat surface and, without holding onto the pot, tap it with an empty sewing thread spool spiked on a bamboo cane. If this produces a ringing sound, the plant needs water; if the sound is dull and heavy, water is not required. (This technique does not work on plastic pots.)

3 It is possible to use a finger to test the compost’s surface, but this eventually compacts the compost.

4 Moisture-indicating strips—sometimes known as watering signals—can be inserted and left in the compost to indicate the need for water.

5 Moisture meters (devices for assessing the moisture in compost) are accurate but involve inserting a spiked probe into the compost and getting a reading on a dial. Doing this repeatedly damages roots.

Dry compost is light in color.

Tap to check for dryness.

Gently feel the compost for moisture.

Moisture meters are accurate.

Saving a Plant with Exceptionally Dry Compost

Sometimes, compost becomes exceptionally dry, especially if watering is neglected in the summer or during vacations.

 If neglect is only superficial, stand the plant on a well-drained surface and water the compost two or three times. At each watering, the compost expands and makes it better able to retain moisture when more water is applied.

 If a plant is dramatically wilting, remove dead flowers and leaves and stand the plant in a bowl shallowly filled with water. When water seeps up to the surface of the compost, remove the plant and allow excess moisture to drain.

Place plants that do not like getting their leaves wet in a bowl of water to absorb water from below.

Rescuing a Plant with Wet Compost

In winter, when houseplants are usually not growing rapidly, plants are sometimes excessively watered, resulting in leaves and flowers wilting. If the compost is not totally saturated, there is a good chance of rescuing it.

With the plant still in its pot, support the compost with one hand and invert the plant and pot. Remove the pot. Use an absorbent cloth or disposable paper towel to soak up excess moisture—repeated wrappings are usually needed. Leave the root ball wrapped in absorbent paper until dry, but not bone-dry. If the root-ball is packed with roots that hold it together, omit the wrapping. When the compost is only slightly moist, repot the root-ball into a clean pot.

Wilting can be the result of excessive watering.

Rescuing and Repotting a Plant with Wet Compost

Remove the pot.

Soak up excess moisture.

Wrap and leave to dry out.

Repot into a clean pot when the compost is only slightly moist.

Type of Water

Most houseplant enthusiasts use tap water, which suits the majority of plants. It is clean and readily available, and it is ideal as long as it is not too cold. However, houseplants such as azaleas dislike lime and grow best in slightly acidic soil. If the tap water is alkaline, boil it and allow it to stand until cool before use. Collecting defrosted iced water from a refrigerator and allowing it to reach room temperature is another option.

Rainwater is ideal, but ensure that it is clean and has not fallen on a dirt-contaminated roof or become stagnant in a barrel.

Stand a plant with dry compost in a bowl of water.

Humidity and Misting

The amount of humidity in the air influences the health and growth of plants. Desert cacti and most other succulents survive in areas with little humidity, but plants native to forests usually need a humid atmosphere.

Signs of Excessive Humidity

1 Leaves and flowers that are tightly packed together sometimes become excessively damp.

2 Flower petals and buds eventually become covered in a furry mold.

3 Soft, hairy leaves become damaged before shiny, all-green ones do.

4 Cacti and other succulents develop patches of decay.

5 Plants with leaves that clasp stems become damaged; water becomes trapped at the junctions of leafstalks and leaves.

Signs of an Excessively Dry Atmosphere

1 Tips of leaves become curled, dry, and shriveled.

2 Flowers fade and become discolored, with flower buds eventually falling off.

3 Tips of shoots wilt and, later, shrivel.

4 Surfaces of leaves become dull.

5 The whole plant wilts if the temperature is high, with leaves eventually falling off.

How to Create Humidity around Plants

1 Stand plants in small groups to create a humid mini-environment.

2 Stand pots in trays with a 1in (25mm) layer of pebbles in the base, shallowly filled with water to just below the top of the pebbles. Moist air can then rise around the leaves.

3 Use a mist sprayer/mister, which is inexpensive, to coat the leaves in fine water droplets, but do not spray flowers or plants with hairy leaves.

4 Mist plants in the morning so moisture can evaporate before night. Dampness remaining on the leaves in late evening encourages the presence of diseases at night when the temperature falls.

5 Mist aerial roots, such as those on Monstera deliciosa and some Philodendrons, to help them to remain soft, pliable, and active.

6 Avoid spraying plants when they are in strong, direct sunlight; water droplets may act as lenses and burn the leaves.

7 Regular misting helps to discourage red spider mite infestation.

Repotting Houseplants

Eventually, most houseplants (except those grown for their short-term display) fill their pots with roots and need to be transferred to slightly larger ones. A plant left in the same pot will slowly deteriorate. When selecting a new pot, check the following.

 The new pot is clean, dry, and about 1in (25mm) larger. When a plant is already in a large pot, perhaps 6in (15cm) or more wide, the new pot can be 2in (5cm) larger.

 When repotting into a clay pot, put a piece of broken clay pot (known as a crock), concave side downward, in the base to prevent the drainage hole from becoming blocked. This is unnecessary when repotting into plastic pots; these are usually filled with peat-based compost, which is more fibrous and less likely to fall out of the smaller drainage holes into the base.

 Use the same type of compost in which the plant is already growing.

Step-by-Step Repotting

1 The day before repotting, thoroughly water the compost and allow the excess to drain. This is essential since a plant with a dry root ball will not rapidly become established in a new pot.

2 Place the fingers of one hand over the top of the root ball and invert it, together with the pot. Sharply tap the rim on a hard surface (without damaging the plant’s leaves), so the pot and root ball separate.

3 Fill a suitable pot with compost to about one-third of its depth and press to lightly pack it. (Add a crock in its base first if it is a clay pot.)

4 Without damaging the root ball, position it in the center of the pot. Check that the top of the root ball is about ½in (12mm) below the new pot’s rim. Add or remove compost.

5 Keep the plant and root ball upright and carefully dribble fresh compost around it. Gently pack it until just covering the root ball. When repotting a plant in a large pot, leave a slightly larger space between the compost’s surface and rim.

6 Stand the plant on a well-drained surface and gently water the compost from above, without unduly disturbing it. A couple of waterings may be necessary. Watering from above also helps to settle fresh compost around the root ball.

7 Stand the pot on a clean saucer or place it in a cachepot. Initially, position the plant in light shade for two to three days, or until established.

Use a cachepot or place the pot on a saucer after repotting.

Feeding

To remain healthy, plants need a balanced diet throughout their lives. For most, this is provided by compost in a pot, with the addition of regular feeding or, for plants in large pots, top-dressing. Regular feeding makes a remarkable difference, and there are three main ways to do it.

 Liquid fertilizers are the traditional, easiest, and most widely used choice for feeding houseplants. Concentrated fertilizers are diluted in clean water and applied to potting composts. First read the instructions and add the correct amount to clean water. Agitate and apply to moist compost. Many bromeliads have urns at their centers (resembling small vases formed by leaves); keep these topped up with water, and add weak liquid fertilizer, usually from spring to late summer.

 Fertilizer pills and sticks are more recent innovations. They are pushed into the compost to provide food for several months. They are best used in spring and up to midsummer. If they are used in late summer, they provide food when some plants are resting. Unfortunately, unlike liquid feeding (which encourages the development of roots throughout the compost), pills and sticks concentrate nutrients in one position, resulting in an uneven spread of roots.

 Foliar feeds are ideal for houseplants that can absorb nutrients through their leaves. Air plants are normally fed in this way. Plants rapidly respond to foliar feeding, and the technique is best used as a tonic for plants with smooth, non-hairy leaves. Avoid spraying flowers or using foliar feeds when plants are in strong sunlight. Strong foliar feeds will burn the leaves.

Remember that not all houseplants need feeding at the same frequency throughout the year. While most are fed during summer, not all need feeding in winter (see the plant directory in Part Two for details). Before feeding a plant, check that the compost is moist; this decreases the risk of roots becoming burned by strong chemicals and helps spread plant foods throughout the compost.

Feeds that are too strong soon damage roots, so it is essential to adhere to the manufacturer’s instructions. To avoid root damage, it is better to provide a plant with a weak liquid fertilizer than one that is too strong.

Dilute liquid fertilizer in water and stir.

Apply liquid fertilizer to moist compost.

Grooming and Supporting

Grooming keeps houseplants attractive throughout their lives. Flowering houseplants need to have dead flowers removed, while others need to be supported or have their leaves cleaned. When removing dead flowers and leaves, put them into a bag and throw them away; do not scatter them around a plant, because decaying pieces of plants are unsightly and encourage the presence of diseases.

Insert a fertilizer stick into the compost.

To prevent fertilizer from going all over the place when you foliar feed plants, simply place the plants in a plastic bag.

Add weak liquid fertilizer to a bromeliad’s central urn.

Top-Dressing Large Houseplants

Instead of being repotted, large plants are usually top-dressed.

Use a small trowel to carefully remove the surface compost without damaging the roots. The depth of the compost that is removed is usually no more than 1in (25mm).

Add slow-release fertilizer to fresh compost and use it to top up the pot so its surface is about ½in (12mm) below the rim. Then, carefully water the compost using a watering can with a rose.

Cleaning Leaves

Houseplants with large leaves, such as the Rubber Plant (Ficus elastica), benefit from having them cleaned. Dust and dirt left on leaves impairs their appearance and prevents sunlight from activating growth processes.

 Use a soft, damp cloth to clean large, shiny leaves. Support the leaf with one hand and carefully wipe the surface. To avoid burning, never do this when the plant is in strong sunlight.

 If a plant has a large number of small, shiny leaves, gently swirl them in a bowl filled with slightly warm water. When clean, remove the plant and stand it away from direct sunlight until dry, or it might burn.

 Use a soft brush to gently remove dust from hairy leaves. Blowing on leaves while brushing them helps to remove dust.

Wipe the leaf with a damp cloth to restore shine and remove dust.

Swirl leaves under water to rinse off dust and dirt.

Use a paintbrush to clean dust off hairy leaves.

Tidying Stems and Shoots

 Some plants become untidy and benefit from having stems and shoots removed. Where a stem or shoot spoils a plant’s symmetry, use sharp scissors to cut it back to just above a leaf-joint. Avoid leaving small stubs, which are unsightly and will die back.

 Young foliage plants often need to have a shoot tip removed to encourage bushiness. Use sharp scissors to cut back the stem to a leaf-joint, or hold the shoot between your fingers and snap it sideways.

 Some variegated plants occasionally produce all-green stems; cut these off.

Trim off untidy long growth with a sharp pair of scissors.

For houseplants with long flower stems, break off from the base of the stem to discourage disease.

Removing Dead Flowers

Dead flowers are unsightly and encourage the presence of diseases if left on a plant. Most dead flowers are removed by pinching them off between a finger and thumb. For houseplants such as cyclamen, remove the complete flower stem and dead flower; leaving short pieces of stem encourages the presence of diseases. Gently tug the stem so it parts from the plant’s base.

Snap off dead flowers between your thumb and forefinger.

Staking and Supporting

When plants need to be supported, it is essential that this is unobtrusive, whether you use traditional materials (raffia, green string, and split canes) or more recent introductions (plastic frameworks and metal rings).

 Most houseplants need little support, but if it becomes necessary, use a thin split cane and soft green string. First tie the string to the support, then loop it around the stem just below a leaf-joint. Metal plant rings can also be used.

 Some climbing plants, such as Jasminum polyanthum (Pink Jasmine), benefit from a supporting hoop formed of pliable canes. When the plant is young and has shoots about 12in (30cm) long, insert pliable canes into the compost and train the stems around the canes.

 Climbing plants with aerial roots benefit from being given a moss pole as support (this is a stiff stake covered with several layers of moss). Use spirals of green string to hold it in position. Tie the plant’s stems to the pole and keep the moss damp.

Form a hoop with pliable cane and attach the plant with string.

A moss pole works well as a support for a climbing plant with aerial roots.

Vacation Care

Invariably, there are times when plants are left unattended for several days. This is not a problem in winter, when most are not very active, but arrangements need to be made to look after them in summer.

Helping plants survive

1 If you are going away for only a few days, place a plastic sheet on the floor in the center of a room and stand your plants on it. Fill their saucers with water.

2 Keep small plants moist by standing them in a shallow tray packed with moist peat.

3 Place a piece of capillary matting on a draining board and trail the other end into a sink full of water. Stand plants directly on it, not in their saucers. This works well for plants growing in peat-based compost in plastic pots, without crocks in their base.

4 Use wicks to keep compost moist in small pots. Push a wick into the compost and trail the other end into a pot filled with water.

5 Shallowly fill a wide basin with clean water and place one or more plants in it. This is ideal for houseplants that like plenty of moisture, such as some ferns.

6 Fill a shallow container with expanded, light-weight clay particles (which resemble small, hard, ceramic, shell-like pebbles with porous cores), add water to just below their surface, and stand plants on top.

Before leaving home

1 Close the door of the room to prevent drafts from drying plants or from pets from knocking them over.

2 Draw the curtains in summer, especially those that face strong, direct sunlight.

3 A week before leaving home, check that plants are not infested with pests and diseases. Spray immediately if they are.

4 Remove faded flowers and those that will be past their prime by the time you return. Remove dead leaves.

Close doors to prevent pets from knocking over plants.

Stand plants on capillary matting.

Use wicks to water plants.

Stand plants in a bowl of water.

Remove faded flowers.

Remove dead leaves.

Houseplant Problems

Few plants can escape from pests and diseases or cultural problems (often known as physiological disorders), such as leaves and flower buds falling off. It is much easier to prevent attack by pests and diseases than to eliminate them from badly affected plants. Here are some prevention tips.

 Buy plants from reputable sources.

 Inspect plants before buying.

 Regularly check for infestations.

 Never use garden soil instead of potting compost as it may contain weed seeds, pests, or diseases.

 Avoid leaving dead flowers and leaves around plants.

 Check root balls for soil pests when plants are being repotted.

 Never use infected plants as propagation material.

The chemicals permitted by legislation vary from country to country and state to state, so if prevention fails, check with your local nursery or garden center about the most suitable insecticide to use for your specific problem.

Pests

Aphids: also known as greenfly, aphis, and aphides, they are the main pests of houseplants. These small, usually green, sap-sucking insects infest flowers, shoot tips, and soft leaves, sucking sap and causing mottling and distortion. They also excrete honeydew, which attracts ants and encourages the presence of a fungal disease called sooty mold.

Control: spray with a suitable insecticide as soon as aphids are seen. Repeat every 10–14 days throughout summer.

Cyclamen mites: these infest a wide range of plants, including cyclamen, pelargoniums, saintpaulias (African Violets) and impatiens (Busy Lizzies). They are minute, eight-legged, spider-like creatures that cluster on the undersides of leaves. They suck sap, causing leaves to crinkle and darken. Flowering is shortened and buds become distorted and may fall off.

Control: remove and burn seriously infested leaves and flowers. Spray with an acaricide. Destroy badly infected plants to prevent the mites from spreading.

Mealy bugs: white, waxy, woodlice-like creatures that live in groups and especially infest ferns, palms, azaleas, and hippeastrums. They suck sap, causing distortion, loss of vigor, and yellowing of leaves. They excrete honeydew, which encourages the presence of ants and sooty mold.

Control: wipe off light infestations with cotton swabs dipped into methylated spirits (rubbing alcohol). Spray with a suitable insecticide or burn seriously infected plants.

Red spider mites: also known as greenhouse red spider mites, they are spider-like, minute, usually red, and have eight legs. They suck leaves, causing mottling and, if the infestation is severe, webs. These are unsightly, reduce air circulation around the plant, and make eradication difficult.

Control: mist-spray daily with clean water (but avoid spraying flowers or soft leaves) and spray with a suitable acaricide.

Scale insects: swollen, waxy-brown discs, usually static, under which female scale insects produce their young.

Control: young scale insects can be wiped away with a cotton swab dipped in methylated spirits (rubbing alcohol). Established colonies are difficult to eradicate, and badly contaminated plants are best burned.

Thrips: these tiny, dark brown, fly-like insects jump from one plant to another. They pierce leaves and flowers, sucking sap and causing silvery mottling and streaking. Undersides of leaves develop small globules of a red liquid that eventually turns black.

Control: spray several times with a suitable insecticide or burn seriously infected plants. Keep the compost moist, because dryness intensifies the damage caused by these insects.

Vine weevils: serious pests in the adult form, when young, and as larvae. Adults are beetle-like, with a short snout. They chew all parts of plants. The larvae—fat, legless, and creamy white, with brown heads—inhabit compost and chew roots.

Control: immediately water the compost with suitable insecticide and spray the leaves. Destroy badly infected plants.

Whitefly: small, moth-like white insects that flutter from one plant to another when disturbed. They have a mealy or powder-like covering and are mostly found on the undersides of leaves, sucking sap, causing distortion, and excreting honeydew, which encourages the presence of ants and sooty mold.

Control: eradication is not easy; several sprayings at five-day intervals with a suitable insecticide are essential.

Diseases

Black leg: a disease mainly of cuttings, especially of pelargoniums; the bases become black and soft.

Control: this is encouraged by cold, wet, airless compost, so ensure compost is well aerated when taking cuttings. If cuttings are infected, they are best removed and destroyed; for rare or unusual varieties, remove cuttings, cut off the blackened area, and reinsert the base in fresh compost.

Botrytis: also known as gray mold, it attacks soft parts of plants, such as flowers, shoots, and young leaves, covering them with a gray, furry mold.

Control: cut off and destroy infected parts. Spray infected plants with a suitable fungicide. Remove dead flowers to discourage spreading. Avoid damp, still air and excessive water.

Damping off: attacks seedlings soon after they germinate, causing them to turn black and collapse.

Control: sow seeds thinly in well-drained compost and place in a warm and well-aerated location. Avoid excessively watering the compost.

Powdery mildew: fungal disease that produces a white, powdery coating. It usually appears in spring and summer, infecting leaves, flowers, and stems.

Control: remove badly infected leaves, stems, and flowers; increase ventilation and keep the atmosphere dry.

Rusts: complex diseases that are more problematic in sunrooms and conservatories than indoors. They produce raised rings of brown or black spots. Plants become unsightly and lose their vigor.

Control: remove and burn infected plants and increase ventilation. Do not propagate from infected plants.

Sooty mold: black, fungal disease that grows on leaves, stems, and flowers covered with honeydew. At first it appears in small clusters, but later covers the entire surface.

Control: spray with a suitable insecticide against sap-sucking insects. Use a damp cloth to remove the black growth from leaves. Flowers are best cut off.

Viruses: microscopic particles that invade plants (and animals), causing disorders in the tissue but seldom killing the host immediately.

Control: regularly spray with a suitable insecticide against sap-sucking insects (which probably introduced the problem to your plants) and burn badly infected plants.

Nonchemical Control of Pests and Diseases

Apart from growing plants healthily, with adequate moisture, food, and circulation of air, there are other ways to keep them healthy and to ward off pests and diseases.

1 Mist plants with clean water where there is a risk (or presence) of red spider mites.

2 Regularly remove dead leaves and flowers.

3 Use insecticidal soaps, which are ideal against a wide range of insects and mites.

4 Investigate biological controls, which means using other insects and mites to control pests. These are especially suitable where insects have developed resistance to chemical controls. Biological controls exist for aphids, caterpillars, mealy bugs, soft scale insects, red spider mites, thrips, vine weevil larvae, and whiteflies. Ask your garden center for advice.

Cultural Problems

Also known as physiological disorders, these are not caused by pests or diseases but by environmental problems.

Wilting: there are several causes, including too much water, too little water, and the result of soil pests that eat and destroy roots. Usually, plants wilt because they are short of water; if the compost is dry, water the plant several times. Alternatively, stand the plant, in its pot, in a bowl of water. Later, remove and allow excess water to drain. If a plant wilts and the compost is exceptionally wet, remove the pot and dry the root-ball.

Leaves fall off: occasionally, leaves fall off as a result of factors such as dry or wet soil, pests and disease, and cultural influences, including a sudden drop in temperature. Reposition the plant and keep it in an even, warm temperature away from drafts. Leaves that become yellow and gradually drop off are the result of excessive watering or inadequate feeding.

Flower buds fall off: this may happen if the plant is in a draft or a dry atmosphere or has received a sudden chill. Buds often drop off if a plant is severely knocked.

Damaged leaf surfaces: lack of water may make the edges of leaves become crisp and brown, but straw-colored patches on leaves, especially soft and hairy ones, are the result of water splashing on the surface, which is then burnt by strong sunlight.

Applying Chemicals

There are several ways in which insecticides and fungicides can be applied to plants.

1 Spraying is the most common method. One way to treat a plant in a small house or apartment is to put it in a large plastic bag, which can be temporarily sealed after spraying is complete.

2 Dusting is popular, and a puffer-type applicator is readily available.

3 Insecticidal sticks can be pushed into the compost. The plant’s roots absorb the chemical and the whole plant becomes toxic to insects.

Safety Tips

1 Follow the manufacturer’s instructions and never use stronger or weaker solutions.

2 Unless recommended, never mix two different chemicals.

3 Check that the chemical is suitable for the plants being sprayed—some plants are susceptible to specific chemicals.

4 Store chemicals away from children and household pets.

5 Avoid spraying if animals are in the room; fish and birds are especially harmed by chemical sprays.

6 Never allow children or animals to lick or chew plants that have been sprayed.

7 Only apply chemicals suitable for use indoors. This will be indicated on the label, but if in doubt, ask your nursery or garden center for advice.