You can tell that spring is on its way without even going out of the house if you have houseplants. Suddenly they seem to shake off their tired, dusty demeanour and show new promise, and if you’ve been longing for weeks to give them some attention, now is the time.
Houseplants are no different from those grown in the garden – they start into new life in spring, grow during the summer, begin winding down in the autumn, and try to rest during winter, although this isn’t always possible in centrally heated rooms. New growth is more to do with day length than warmth, so even if your plants are kept at a temperature that is comfortable for you in winter, they will not produce healthy growth, just pale and spindly shoots and foliage. Cutting back and repotting during their dormant period will not help them, and can even cause them to die, but now is the time when you can start giving them the attention they require for good development.
Repotting isn’t always necessary every year. If your houseplant looks well and the compost absorbs water easily, then you can wait at least another year, maybe two, as over-potting can do more harm than good, causing the roots to die rather than extend. If, however, you find water tends to run off the surface of the compost rather than sink in, and roots are fighting their way through the bottom of the pot, chances are that repotting is needed. Turn the pot upside-down with your hand over the top of the compost; if a tight ball of roots falls out easily and there is little or no compost to be seen, it’s time for a re-pot.
Use a new pot only a centimetre or two wider and deeper than the old one, and a good-quality potting compost, recommended on the label as being suitable for houseplants. Make sure you don’t leave any air pockets between the root ball and the pot sides, and water thoroughly once the job is done. Really large houseplants may only need repotting once every five years or so; they should be growing in a soil-based medium by this time. Remove any decorative mulch and the top two or three centimetres of existing compost and replace with new before putting back the mulch.
You don’t need to prune tall houseplants, but those like dracaena, ficus, hibiscus, kalanchoe, citrus and jasmine can get quite bare and leggy without an annual cutting back. The earlier in the spring this is done, the quicker the plant will bush out and thicken up, and, where appropriate, start flowering again. Others, like aspidistra and African violets, can be divided once mature – only use small pots for the new plants formed by division and pot on into larger ones once you are sure the new roots have occupied all the compost. You may need to do this once or twice during the summer.
Regular feeding should start now and continue throughout the growing months. There are specific fertilisers for houseplants; some come in stick or tablet form for slow release over several weeks, others as powders or liquids. Ideally, if you have flowering plants you should use one formulated for these, and another for any foliage plants, as their nutrient requirements are different, although any soluble food with instructions for use on houseplants can be applied if you prefer stick to one or two plant feeds.
Poorly houseplants should be handled with care. Don’t feed or pot on while they look sickly, instead, water sparingly and give the best light possible (not direct, hot sunshine). At this time of year, they will soon show signs of healthy growth if they are likely to recover. When they get enough foliage to indicate recovery, then they can be repotted, but they will not need feeding immediately as there will be enough fertiliser in the potting compost for the next few weeks. It’s surprising how many seemingly dead houseplants can be brought back to life with this treatment.