A healthy plant bought from a shop or nursery should be self-sufficient for at least three months. The basic mixture in which it is planted should contain the right mineral salts and the plant should not be pot-bound. If this is the case, the soil will require a minimum of care for some time. It must be remembered that supplementarycan be dangerous. Sick or waterlogged plants, if fed, will merely have their troubles accentuated but a pot-bound plant, or a rapid grower, probably needs a pick-me-up. The soil should be moist before feeding and should be watered after feeding to avoid any risk of burning the sensitive rootlets with the stimulant that has been decided upon. Weak manure is, of course, an excellent fertilizer.
One cupfull of dried cow manure put into a bag and suspended in a gallon of water for about four weeks is a very suitable liquid food, but even if it is obtainable, which is doubtful for occupants of a flat, it does have a scent which is certainly not the favourite of most people. There are, fortunately, a number of useful, handy, stimulants fertilizers in granular or powder form such as bone meal or plant tablets, although it is doubtful whether any of these can give such an even performance as a liquid . There are many suitable proprietary brands on the market today.
A complete fertilizer suits most plants and will contain nitrogen, phosphorus and potash. Nitrogen promotes foliage growth and a good green colouring. Phosphates are helpful in assisting in the formation of, fruits, and .
Potash helps plants to resist disease, while at the same time strengthening growth. On no account should a sick plant or a new arrival be fed; nor a newly potted plant. A plant that is resting should not be fed and most plants rest during the winter season. Feeding should begin when the plant starts into growth and should go on during the spring and summer.
Plants should not be over-fed and the instructions on the packet should be followed very carefully. A little less fertilizer should be given rather than a little more and all fresh manure must be avoided. Manure must have been well decayed for a long time, otherwise it will burn plant.
The composts that are used for growing house plants have been greatly simplified during recent years. There used to be a special mixture for practically every different pot plant but now, thanks to the John Innes Horticultural Institute, standard mixtures have been evolved. These can be used to serve a wide range of plants and, unless house plants are grown on a fairly large scale, it is much easier to buyready mixed from a reliable supplier.
Some house plants such as dieffenbachias, philodendrons and monsteras, do require special composts. These plants have soft fleshy roots and need a porous open growing medium that is a mixture of two parts fibrous loam, two parts peat and one part sharp sand. Most of thethat are grown as house plants are epiphytes and in their natural surroundings grow on the branches of trees. These require a compost that is almost entirely organic matter since they are watered through the cup-like vasein the centre of the plant, not at the roots. A good mixture is made of equal parts fibrous loam, flaky mould, rough peat, and silver sand. It is also possible to grow house plants in vermiculite which has a perfect texture for house plant roots but contains no nutrients, so the plants have to be fed fairly often.
It is impossible to give any hard and fast rules forbut, basically, soil should be allowed to become almost dry before more water is given, although the soil should never be allowed to dry out entirely, The surface of the soil often is misleadingly dry and it should be scraped about é inch down to see the true nature of the soil.
Over watering is far more dangerous than too little watering, although goodwill reduce this danger. Most plants need watering about two to three times a week in summer, only once a week in winter. A plant that must be left for a few weeks can be thoroughly soaked and put in a polythene bag, tying the bag at soil level around the plant. A thin wick of tape leading to the from another vessel is a good self-watering method that can also be adopted.