The Secret Of Success With Houseplants
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Probably the chief failure to grow any plant successfully indoors is overwatering. Excessive concern with watering by keeping the compost saturated all the time, even during the resting period, is an act of kindness which kills. Sodden compost becomes sour, increasingly acidic and deprived of oxygen. Under these conditions, plant roots die through lack of air and fungi attack the stem at soil level. Constant watering washes out the plant foods which, unless replaced, results in starvation.
No set rules can be laid down as to how often a plant needs water; this depends entirely on the type of compost, temperature of the room and whether it is in active growth or enjoying a rest. Some plants, in any case, need more moisture than others. 'Mother-in- Law's Tongue' will survive a drought better than a 'Busy Lizzie' because it is adapted to growing in the desert regions. To check if a plant needs a drink, scratch the surface of the compost (fig 1) - if it is moist a quarter to half an inch down then do not water. Conversely, if the soil is dry then plunge the pot to half its depth into a bowl containing rainwater or tepid mains water and leave until the moisture rises to the surface of the compost (fig 2).
Plants such as Azaleas, which are killed by lime can be watered with clean rainwater or water collected when defrosting the 'fridge'. Applying water to the top of the pot until it runs out of the bottom, is not one recommended. Compost can be sopping wet at the top whilst remaining bone dry at the bottom. Allow the pots to drain before returning them to their pot holders. In most cases it is a mistake to stand a pot in a water filled pot holder - after a time, the roots may damage. Pot holders are just an insurance against water running out of the drainage hole and damaging the carpet or furniture. In warm, bright weather a plant will need more water than during a dull, cold period - water them according to weather, season and state of growth.
Temperature and humidity
Though many houseplants will put up with considerable fluctuations in temperature, a too rapid and frequent variation will do damage. Many houseplants will withstand quite cool temperatures providing these are constant or change in climate is gradual.
The majority of houseplants are damaged if grown in a very dry atmosphere. The leaves lose moisture so quickly, the roots cannot replace it, even though well supplied with water. Unfortunately, the air in a centrally heated house is usually very dry. Standing the pots in a tray of moist gravel (1), or plunging them in a container filled with peat (2) or damp newspaper will improve the humidity. As the material dries it maintains a layer of clammy air around the leaves. Spraying the leaves every day with water will also help. The pint sized container sold for applying pesticides is ideal for providing the fine mist of water which helps the plants without ruining the furniture.
Draughts are as objectionable to plants as they are to human beings, so avoid places near doors which open directly outside. Extremes of heat are just as injurious. Positions near an open fire, alongside a radiator or on top of a television set will soon cause browning of the foliage. Moist heat is a different matter; plants like the 'Saintpaulia' (African Violet) thrive on a bathroom windowsill.
There is little point in spending time and effort in cultivating a plant with beautiful foliage if the colour is marred by a coating of grime. The
leaves are covered with tiny holes and it is through these that the plant takes in air, passes out waste gases and evaporates surplus moisture. Dust clogs up these holes, reducing their efficiency, so cleaning the leaves makes them more attractive and improves their function.
A wipe with a soft moist cloth or cotton wool once a week is all that is required. Alternatively, special products canbe bought which after application, put a gloss on the leaves, while at the same time removing the dust.
Always, when trying one of the leaf cleaning chemicals for the first time, check that it will not harm the plant. Test on one leaf of the plant. If that leaf is not harmed, it can safely be used on the whole plant Except The Young Leaves - Never handle young leaves.
No plants, not even ferns, so popular in Victorian houses, will grow in deep shade. Most prefer good diffused daylight with shade from direct sunlight, particularly at midday during summertime. There are plants which can accommodate bright sunlight, just as there are those which will adjust to quite shady conditions in a north facing room, but the majority grow best in good but diffused light. Dark corners can be improved by fitting special lighting, but normal house lights are not usually bright enough to recompense for the absence of natural light. Rooms with only very small windows will be unsuitable for growing anything but the hardiest of houseplants.
Feeding is adjusted according to need, taking into consideration the time of year, vigour of growth and whether the plant has recently been re-potted. When a plant is dormant, it does not need feeding. On the other hand, in the full vigour of growth, a heavy foliaged plant may need feeding every 14 days. After re-potting, no extra fertilizer is needed for three months or even longer.
What type of feed is used depends on personal choice or availability, provided it is specially formulated for indoor plants. Single action fertilizers as opposed to mixtures are used to correct an obvious deficiency. For example, the yellowing of the leaves on 'Citrus Mitis' which indicates a lack of magnesium, can be corrected by watering with a pinch of Epsom salts dissolved in a pint of water. Otherwise, mixtures containing a proper balance of nitrogen, phosphates and potash, either in liquid, powder or tablet form will supply all the food required.
Whatever the fertilizer chosen, there are two golden rules to observe before applying it. First, READ the instructions on the packet carefully and DO NOT add just that little bit extra above the recommended dose - it will do more harm than good. Excess fertilizer soon sours a compost and in some cases will actually kill the plants roots. In fact, overfeeding of houseplants will do almost the same amount of damage as starving them of nutrients. A mass of foliage which is soft and too large indicates excess, whereas hard, stunted growth means the roots are starved.
Never feed a sickly plant, i.e. one where the foliage is going brown or yellow or wilting. Sick plants like human beings need to have the cause of illness diagnosed and then treated. Check for overwatering or dryness at the root or in the atmosphere. Make sure there are no draughts or fumes and finally see that the roots are not pot-bound.
Information sourced from the PBI HOUSEPLANT EXPERT (Dr D.G. Hessayon)