April in the Garden

When writing about roses last month I forgot to mention that, even though I tend to leave the final pruning until relatively late, it is good practice to shorten the overall growth before winter. I was reminded of this during all the recent high winds and blustery downpours, during which any non-shortened specimens ran the risk of ‘wind rock’.

This phenomenon was more of a problem when serried ranks of hybrid tea roses were grown, in massed displays, with bare soil all around. If they weren’t cut back, at least partially, before winter then high winds, combined with sodden soils, could lead to the bushes being blown backwards and forwards in the ground. In the worst cases this led to root damage and the resulting risk of plant death or, at least, poor performance.

For the same reason, fast growing, often ‘top heavy’, plants, such as buddleia, should be cut down by two thirds in the autumn and then reduced to practically a stool (the posh term for a stump) at the beginning of the growing season—right about now. Their spring extension growth is so fast and sappy that, if chopped down too early in the season, there is a chance that late frosts wipe out all the newly sprouted shoots. They are so vigorous that it’s better to lose a proportion of new growth, visible now, than to chop them back during the depths of winter. As with so many gardening tasks it’s a question of balance, no two years are the same, and it’s foolish to be a slave to ‘hard and fast’ rules.

We are at the tipping point of the gardening year when it really does feel that winter is being left behind and the re-greening of the countryside gathers momentum. Buds burst from bare stems and spring bulbs double in size and abundance overnight. The first battalion of spring bulbs are going over, to be replaced by blousier, bolder, beauties, such as the taller daffodils and the first of the showier tulips.

Whilst in leaf, before they start to die down, it’s worth feeding the spring bulbs in order to give them a chance to replenish their expended energy and to encourage them to flower again next year. In beds and borders I rely on the trusty application of fish, blood and bone, my ‘go to’ general purpose fertiliser, but in containers, where floral displays have to work really hard, April is the first month in which it’s worth applying a chemical ‘slow release’ fertiliser.

These granular feeds rely on clever science, regulated by soil temperature and moisture, to release a balanced supply of plant food over the growing season. Their expense is best justified in situations where plant growth might otherwise be limited by finite soil volume or an otherwise artificial planting situation.

With rising average temperatures and a diminishing risk of hard frost there’s more opportunity to sow hardy annuals this month than there was last. Also sowing lawns from scratch can take place now, following rigorous seedbed preparation, as long as you can provide some sort of protection from heavy downpours which would otherwise wash the seed and fine tilth away.

Plants which have been wrapped up in fleece, to fend off the worst of the winter cold, can be unwrapped during mild spells.  Keep the fleece close at hand for rapid deployment when frost threatens. Open up cold-frames, greenhouses and conservatories, whenever it is sunny, to encourage ventilation and begin the hardening off process. If you took tender perennial cuttings in the autumn, and they are still in pots or seed-trays, then these should be separated out and potted up as soon as growth resumes.

It’s a good time to plant out containerised trees, shrubs and herbaceous perennials as growth is well underway, which makes establishment easier, and water should be in good supply. You’ll still need to thoroughly water them in, as always, and to keep them well-watered during warm, dry, weather.

This is the optimum time for planting evergreens. Unlike deciduous plants, which shed their leaves and require very little water while denuded, evergreens are always ‘in leaf’ and losing water by transpiration. The danger of planting them in the coldest months of the year is that, if the surface soil becomes frozen, then the water cannot be absorbed because the roots will not have had a chance to extend to a depth below the frozen soil.

Planting at the beginning of the new growing season allows for rapid root growth, assuming you remember to loosen the root-ball when you plant it, which will stand the evergreen in good stead by the time it faces the danger of frozen ground next winter. As usual, it is imperative that it is kept well-watered, after its initial watering in, for at least the whole of its first growing season. Evergreens are very prone to becoming stressed, eventually dying, if at any point they are droughted. They are most at risk during the first summer after planting—hence the need to water them whether you think they need it or not!

Again, with recent high winds in mind, it’s worth remembering that it’s not only blazing sun that dries out the soil and plants. Air flow over leaves massively increases the transpiration rate, the method by which water is lost, and strong winds will dessicate foliage if the plant cannot absorb water from the soil as quickly as it is being lost from the leaves. In serious cases this leads to the effect known as ‘wind burn’ where the foliage becomes shrivelled and blackened, looking like it’s been burned by fire.

A final thought, as I’ve not mentioned them recently, is that increasing average temperatures will lead to an exponential increase in the prevalence of pests, diseases and weed growth. All of these gardening bugbears require ongoing vigilance if they are to be kept in check and not allowed to get out of hand. Whatever method you choose to control them, be it organic or chemical, then the key is to nip any problem in the bud. Gone are the days when gardeners expected to completely eradicate all the gardening ‘nasties’ because that really did require an awful lot of chemical intervention.

Today’s more balanced approach, allowing a degree of ‘live and let live’, leads to a more harmonious, more sympathetic, gardening culture which makes growing plants less of a battlefield, I hope.