Hannah Genders offers some tips for getting your garden spring-ready.
This is the month where gardeners start to come alive again. There is a lot to do in the whole garden, and the light has changed into a “growing” light.
PRUNING
There are some shrubs that require pruning in March to avoid them becoming woody and to help them flower well. Buddleia davidii is one such plant. On a mature plant, cut back the stems to around 30cm above the ground, remove any diseased wood and any overcrowded branches, particularly in the middle of the plant.
Buddleia is a colonising plant and you can see it growing in cracks in walls in many urban settings. Its common name is “the butterfly bush”, and it has a great value in our gardens to attract all the native butterflies. So, if you have room, plant one in a sunny spot.
Cotinus is another shrub that can be pruned now. I have both Cotinus ‘Grace’ and Cotinus coggygria purpureus; both plants have a similar habit, and the cultivar ‘Grace’ is particularly good for autumn colour. The common name for this shrub is “smoke bush”, and this refers to the flowers which are small and create a smoky haze over the foliage. I’m not particularly keen on the flowers and grow the plant mainly for its leaves.
If you want striking leaf colour, cut the shrub back now by one third and remove the old, grey wood. Prune for shape as well taking out any crossing branches in the middle of the plant. You will lose flower by doing this pruning, but you will be rewarded with great leaf colour which is excellent for flower arranging.
Forsythia is a common shrub, brightening up many gardens with its vivid yellow flowers at this time of year. Once it has finished flowering, pruning can start, as if left untouched a mature Forsythia will become very woody and not flower well. To regenerate an old shrub, cut back one third of the whole plant to the ground, starting with the oldest stems. Once you have created a framework, every spring cut back the side stems to three buds from the main branches.
As a general rule, most shrubs that require pruning are best done after flowering.
PONDS
Wildlife ponds will be coming to life now in March. Newts, for example, have a life cycle of hibernation over winter, but they will now be in your pond preparing to breed. All newts, including the rare great crested newt, will be looking very dapper with their orange bellies and crests ready for mating.
A pond, whatever its size, needs to be cleaned out in spring. Remove all the dead leaves and debris that have blown in, as this rotting material will create phosphates in the pond water as it breaks down. This in turn increases the nutrient content, contributing to algae blooms as the water warms up.
The “life” of the pond is in the micro-organisms and insects living in this debris, so as you clear it out, pile the material on the edge of a shallow area of the pond, allowing everything to crawl back in overnight.
Cut back any reeds to encourage new growth – this will clean the pond water as the nitrogen uptake in the new plant growth will act as a natural filter.
PERENNIALS AND GRASSES
I love using ornamental grasses in my designs and planting schemes; they add such great texture and movement to a flower border, but they do need some care at this time of year. I leave the stems and plumes on the plants over winter to act as a protective layer during frosts (not that we’ve had many this winter) and for birds to feed on the seed heads.
The new green growth should be showing now at the base of the plant, so cut back the old growth to these new shoots and weed out any perennial weeds that have taken hold. Fork around the plant and add a good quality mulch of well-rotted garden compost. The large ornamental grass Stipa gigantea, which I love for its six-foot plumes in the summer, responds well to a clip over with shears to retain its shape at the base; again fork around and mulch as before.
Similarly, most perennials which have a base growth and then tall spikes of flowers from last year now need a trim back. Like the grasses, I have left this growth on for winter protection and now I cut it back to the base, taking care not to damage the new growth coming through. Sedums, chrysanthemums and asters are all examples of perennials that need this pruning. Mulch around the plants for a spring feed when you have tidied them up.
VEGETABLES
You can really get growing this month in the vegetable garden, both outside and inside if you have either a greenhouse or polytunnel. Outside, if you missed putting on a mulch in the autumn, add it now – about one- to one-and-a-half inches of well-rotted compost, mushroom compost or garden manure where you are planting beans or peas. Don’t dig this mulch in; let the worms and bacteria do the work, just hoe off any light seedlings that have appeared and start planting.
You can plant onion sets (protect them from birds), chard, spinach, spring onions, lettuce and carrots. In the greenhouse, start some seeds off to plant out later in May: peas, beans (both the climbing french beans and bush beans), runner beans and courgettes. Here is a tip for courgettes: if you soak the seeds overnight, they become much more viable and sprout more easily.
Grow all these seeds in good quality peat-free compost and water, just enough to dampen the soil but not soak it so much that the seed rots before it sprouts. Oh, and do label everything well; it’s so easy to forget what you have planted.
LAWNS
Some maintenance can now be done on lawns – a high cut and a rake-off to clear any debris is a good start. If any areas need re-seeding or turfing, this month and next are ideal. Now here is a plea: don’t over-fertilise the lawn. An organic fertiliser which gives a balanced feed without too much nitrogen is ideal.
Don’t use insecticides – it harms the bees – and please leave a few daisies and clover to flower; you will be rewarded with more bees and beneficial insects in your garden. Let’s start a trend for tapestry lawns that are kinder to our insect friends and more appealing to the eye. I’m told this trend is coming – I hope so! Happy gardening.