Post category: Feeding
When to feed
House plants depend entirely on whatever nutrients are in the compost, or are added to it subsequently. Potting composts have enough food for about two months. After that, plants must be fed for continued good growth.
Dieffenbachia needs regular feeding
Which feeds to use
Soluble plant food formulations are easy to use and safe for the plants. Solid fertilisers too easily lead to overfeeding and it is best to stick to special houseplant feeds. There are many brands: Phostrogen, Kerigrow, Baby Bio, Hygeia Plant Food, Miracle Gro, Algoflash, Shamrock and J. Arthur Bowers.
Some brands are high in nitrogen, which is the first figure in the analysis given on the packet or bottle, for instance 10:2:4. These are suitable for foliage plants. Flowering plants need a more balanced feed, such as the formulae 7:7:7 or 5:4:4.
Most kinds of plant food contain trace elements. Use slow release plant food tablets, or spikes, to reduce the frequency of feeding.
Too much feed
In extreme cases, too much plant food can cause a plant to wilt and die, especially when excessive plant food is applied to a dry pot. Constant over-feeding can cause stunting and brown edges to the leaves.
Quite often, over-feeding causes rapid, dark-green leafy growth at the expense of flowering; this is typical of geraniums. Over-feeding can give rise to a white salt deposit on the compost surface. However, in a ‘hard’ water area, this simply may be lime in the water that rises to the surface of the compost.
Too little feed
When plants are short of nutrients, growth is weak with small, pale leaves and thin stems. Often the leaves have yellowish blotches, or markings, between the veins.
On poorly fed plants, the flowers sometimes have poor colour, and the flower heads tend to be small. Stems and leaves can take on a purple tinge, especially in peat composts. Older leaves, or young leaves, can go yellow, and fall off or shrivel. Stems are spindly.