If everything was starting to show itself in March, by April it’s hard to turn around without bumping into something blooming, bursting or putting on so much growth it’s slapping you in the face as you do.
Trees and shrubs like Amelanchier lamarckii and Spiraea ‘Arguta’ are blossoming, and I’ve a great ornamental bramble, Rubus spectabilis ‘Olympic Double’, offering rose-like flowers towards the end of the month. There are spires of blue Camassia and low-growing Aubrieta ‘Purple Cascade’, and in shadier parts white and deep-red Lamprocapnos (or Dicentra) spectabilis.
It’s also tulip time – though the display I managed last year is beginning to show the signs of needing to be topped up. Darwin hybrids tend to be the most reliably perennial and – though I find the colours and varieties more limiting – if you plant them deep enough in the border, they should flower for three years, possibly more. They’ll never last as long in a container, however.
There’s often plenty of sun and warmth around this month, but overnight temperatures can still drop and there can still be damaging frosts into May. Be prepared for the worst by having some horticultural fleece to hand and sling it over your most tender plants.
As well as frost, watch out for plant predators as all this new growth is total slug-bait. The young shoots of delphiniums and hostas seem to be especially high on their menu in my garden.
As they finish flowering, I’ll divide primroses and spread them around the garden and I’ll also start adding half-strength liquid tomato feed to my choicer plants every other week: greedy roses and also peonies and clematis will benefit, but anything that looks like it needs a boost gets a dose too. I’ve never done this before but you can also feed spring bulbs as they flower and then go over. I’ve always left the leaves when they do but tomato feed will give the bulbs an added advantage for next year.
If you have a fernery (and who wouldn’t, they’re brilliant and many ferns provide welcome winter interest in the garden), it’s time to cut back the tatty fronds as the new ones start to unfurl. They appreciate a good layer of mulch to retain moisture and – although they don’t usually need it – a bit of slow-release fertiliser if you like.
Feeding anything will, of course, encourage lots more growth so get your plant supports in early before plants get too large. I use a variety of kinds: two levels of string between stakes for plants to grow up through the gaps, tall hoops criss-crossed over my delphiniums, metal peony cages, beanpole tripods for some of my more vigorous roses, and rusted arches and obelisks for clematis.
When it comes to clematis, as well as the rhyme ‘if it flowers before June, do not prune’, it’s worth remembering the gardening adage that ‘the first year, plants sleep; second year, they creep; and third year, they leap’. Basically, don’t give up on a plant if it looks like it’s underperforming when you first plant it. Although you almost expect it in the first year of planting, I’ve been disappointed in many clematis when they don’t put on the growth I’d expected. However, give them a couple of years to get their roots well stuck in and in year three, they’ll be off, flowering their little hearts out and generally getting in the way of everything else.
Cut back the late-summer flowering, vigorous Clematis viticella now to healthy buds a couple of feet above ground, feed and mulch – clematis like cool roots with their flowers in the sun. Then be ready to tie them in as they grow.
One final (not final for the year, steady on!) job is to check pots and containers to see if any look unhappy. Check if the cause is being pot-bound by tipping them out to check the rootball and, if necessary, repot them in something a little larger. My agapanthus are an exception as they flower better when packed tight into their container. Then all container plants will benefit from the top few inches of old compost being replaced with fresh.
So what are you waiting for? It’s the middle of spring, time to get stuck in!
Dedham Horticultural Society 