Temperature
The temperature range given for each plant is the optimum at which it
will sustain its rate of growth and overall health. Itis essential to provide
a stable temperature, preferably towards the middle of the range. Plants
that are kept too warm during the day and then too cold at night often
shed theirfoliage. For the same reason itis importantto keep plants away
from draughts.
Problems caused by temperature occur most often in late autumn,
winter and early spring, when many plants are in their vulnerable resting
phase and fluctuations of heat and cold are more likely.
Aspect/Light
All plants need light to manufacture the foods that enable them to grow
and produce healthy foliage and flowers. The amount of light needed
varies between the differentspecies so the positioning of plants is of vital
importance. Ferns prefer rather more shade than other plants as their
deep green foliage has evolved to collect low levels of light. Conversely,
highly coloured foliage plants will lose their bright colours if they are
deprived of the sunlight that creates them.
Humidity
The amount of atmospheric moisture a plant needs depends upon the rate
the water drawn up from its roots is lost through its leaves – the process
known as transpiration. Cacti and succulents have fleshy tissue, which
can store water, so they do not require a humid environment. Ferns and
some other plants have thin leaves, which lose water rapidly. Without a
high level of humidity they soon shrivel and turn brown at the leaf edges,
and will die if no remedial action is taken.
Most problems occur with plants that require high humidity, as many
homes have a dry atmosphere caused by central heating. Regular misting
helps to increase humidity and is recommended for many plants.
However, with species that also require bright sunlight, spraying can
cause marking ofthe foliage. Another solution is to place the plant on a
tray or saucer of moistened pebbles so that moisture evaporating below
and around the plant willincrease the humidity. Yet another technique is
to group plants in a bowl, planter, terrarium, or simply in their individual
pots, so they create their own humid microclimate.
Watering
More plants fail because of problems with watering than for any other
reason. The amount of water needed can vary greatly between the
different groups of plants, and it is also dependent on temperature,
humidity, light, time of year, size of pot, and even air movement.
This book provides specific watering instructions for each species but
there are some general guidelines that should be followed. Tap water is
acceptable for most plants, although it should be allowed to adjust to
room temperature prior to use. If rain water is recommended, the rain
should be collected and stored hygienically.
With most plants, water can safely be provided through the surface of
the compost, provided it is allowed to drain into a saucer below and the
surplus is discarded. Unless the plant is an aquatic it should not be left
sitting in water, otherwise the roots will rot and the plant will die. Avoid
splashing water on to the foliage, as this will cause it to rot or become
scorched or marked.
Frequency of watering is also important. Ferns, Azaleas and some
other plants should be kept constantly moist. Cacti and succulents
should be watered infrequently, with more in spring and summer, when
actively growing, but the barest minimum in autumn and winter, to
prevent them from drying out completely. With most other plants it is
usually a good policy to allow the compostto get on the dry side before re¬
watering. Do not let it dry out too much as the plant will wilt and the
compost will shrink back from the pot and allow water to drain away
rather than absorbing it. A final point to note is that not all plants that
wilt are too dry; they often wilt when they are too wet. It is therefore
important to judge the condition of the compost very carefully before
each watering, by probing beneath the surface with a finger.
Feeding
As with watering, there are no fixed rules as to how often plants need to
be fed. Feeding should take place only during a plant’s active growing
season, never when it has slowed its rate of growth or is dormant. Moisten
the compost before applying the fertilizer and ensure that it is used at the
strength recommended for the plant.
The type of fertilizer to use depends on the plant and its stage of growth.
A general houseplant fertilizer, high in nitrogen, can be used for most
foliage and flowering plants to promote lush foliage. With flowering
plants, once the foliage has become established it is best to switch to a
flowering plant fertilizer, rich in potassium. This will help produce better
quality flowers. Tomato fertilizers achieve the same result but should be
diluted as recommended by the manufacturer.
Slow release or controlled release fertilizers save the trouble of mixing
and can be simply applied as pellets or sticks that are either sprinkled
over, or inserted into, the compost.
Pruning
Pruning is necessary to maintain a compact habit and to encourage
bushy growth. In most cases it is simply a matter of ‘pinching out’ the
foliage using the thumb and forefinger. Woody-stemmed subjects, how¬
ever, require the use of sharp scissors, secateurs or a pruning knife, and
plants with particularly thick stems must be pruned with a saw.
It is important when pruning to leave a clean wound with no bruised or
ragged tissue that could become infected with disease. Trim back to a
position just above a leaf or bud as long lengths of bare stem can ‘die back’, leading to disfigurement or loss of the plant. A few species ooze a
milky sap. This can be dealt with by sprinkling charcoal over the cut to
congeal the sap and seal the wound.
Some plants, such as Poinsettias, produce leggy and untidy growth
that requires rather more than a light trim. They should be cut back by
half to two thirds in the spring in order to produce a reasonably compact
plant the following season.
Grooming and cleaning
Dead flowers or brown leaves should be pinched out or trimmed off
immediately, both to maintain the appearance ofthe plant and to prevent
the spread of disease. After removing diseased tissue, clean and disinfect
any cutting tools before using them on other plants.
It is not usually necessary to clean leaves more than a couple of times a
year. Avoid aerosol leaf shines or oily sprays as these may damage the
plant. Plants with tough, waxy leaves should be wiped gently with a damp
cloth or cotton wool to remove dust and grime. Clean the top surface only,
never the bottom. Other plants can be cleaned by spraying or rinsing the
foliage with tepid water. Soak up excess water with a kitchen towel and
allow the plant to dry away from sunlight.
Cleaning is best carried out when plants are actively growing; during
their dormant period they are more susceptible to damage.
As well as cleaning the plants themselves, ensure that the soil is kept
clear offallen debris as this can also become infected with disease.
Training
Plants with a climbing habit need some means of support. Small plants,
such as Philodendron scandens, simply require a small stick or stake,
while loose, leggy plants, such as Achimenes, should be provided with a
light framework ofsticks placed around the pot and linked with string.
Climbing plants with a bushy habit need a trellis or hoop. In all these
cases, attach the plant to the support with small wire rings or string.
More vigorous plants, such as Monstera, require a moss pole for
support. Attach the plant to the pole with string or with hairpins or pegs
formed from bent wire, and moisten the pole regularly with a hand mister.
Plants that both climb and trail, such as Hedera, should be grown in a
hanging basket where the stems can both hang over the sides and climb
up the supporting ropes or chains.
Pots and potting
Whether to use clay or plastic pots is largely a matter of personal
preferance as there are argumentsin favour of both types. Plastic pots are
cheaper, lighter, less breakable and easier to clean. Clay pots, on the
other hand, can absorb and release moisture, allowing the plant’s roots to
‘breathe’, and provide more stability than plastic pots.
Repotting into a larger pot is necessary not only to provide a plant with
more space for its roots to grow but also to increase the reserve of
nutrients and the moisture-retaining capacity, and to give the plant more
stability. Repotting is best carried out during the plant’s growing season.
Frequency depends on the plant, but once every two to three years is
probably often enough for most varieties. Select a pot that is no more
than 7.5-10cm (3-4in) larger in diameter than the previous one. Do not
re-pot plants that are diseased, suffering from root failure or stressed as
the shock could be fatal.
When plants reach a certain size it may be impractical to re-pot them
into an even larger pot so just replace some of the compost in the existing
pot every three years or so.
All the plants in this book can be grown successfully in ordinary
houseplant potting compost. However, when potting cacti and succulents, orchids or bromeliads, try to obtain the composts that are specially
manufactured for these plants.
Bottle gardens
Bottle gardens and terrariums make an attractive feature and also serve
a practical purpose in protecting plants from gas fumes and draughts, and
enabling them to create their own humid micro climate. As space is
restricted it is best to use smaller varieties, such as Fittonia, Maranta,
Peperomia and Pilea. Planting the garden is a delicate operation,
requiring some skill as well as improvized tools. First ensure the bottle is clean. Then pour in some gravel or charcoal through a funnel to form a
base for drainage and cover this with a layer of compost. Next insert the
plants and firm around them. Finally, give the plants a light spray with a
mister and trickle a tiny amount of water down the sides of the bottle to
remove dirt. The bottle should be placed in good light but away from
direct sun. Do not seal it. Keep a check on the compost to ensure that it
remains moist; the plants should not need spraying very often, if at all.
Remove any dead leaves or other debris.
Problems
Problems relating to temperature, light, humidity and so on are dealt
with under those headings. This section explains how to combat the pests
and diseases that affect indoor plants. Always remember, though, that
prevention is better than cure. A plant that has been well cared for should
be strong and healthy enough to resist most infections and diseases so
follow all the care instructions strictly. Carry out regular check-ups for
pests and diseases and put any sickly plants into quarantine to prevent
the problem spreading to healthy plants.
Most pests and diseases can be dealt with effectively using the range of
products detailed in the chart overleaf. Always follow the manufacturer’s
recommendations for the safe use, storage and disposal of these products.
Chemicals are available in liquid concentrate or powder form to be mixed
with water and applied through a hand mister, or as dust or aerosol
sprays. Check that sprays do not contain CFCs (chlorinated fluoro-carbons), which damage the ozone layer. If possible, always use sprays
outdoors, but away from direct sunlight to avoid scorching. Some
chemicals can be applied directly with a paintbrush or a matchstick with
cotton wool wrapped around the end. If in doubt as to whether a chemical
can be used on a plant, check with the manufacturer. If this is not
possible, test the product on one or two leaves first.
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