Prick out seedlings
Continue to prick out seedlings before they become straggly. Shade seedlings in the greenhouse on sunny days, as they can quickly wilt and die. Don’t water seedlings with cold water direct from the water-butt or hose pipe. Keep a couple of cans filled and inside the greenhouse so the water is at the ambient temperature.
Create an evergreen hedge
Plant evergreen hedges. Prepare the site well, adding a couple of handfuls of garden compost per plant. Water well over the next few months as the plants settle in.
There is still time to divide overgrown clumps of herbaceous perennials. Water well after transplanting, and keep moist in dry spells.
Watch out for slugs and snails
Slugs and snails will become very active. Most newly emerging shoots will be at risk. Act now and destroy their egg clusters, translucent milky spheres, usually laid in nooks and crannies in the soil, and down the sides of pots. Delphiniums and newly emerging hostas, in particular, are at risk. Once the soil has warmed up enough, apply the slug nematode. They will get rid of soil-dwelling slugs but not snails. Use all controls available. Don’t rely on just one method.
Aphids can multiply rapidly during mild spells. Remove early infestations by hand to prevent the problem from getting out of hand. Protect sweet pea plants in particular, as they can get sweet pea viruses.