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.