May
Tie-in your climbers, prune spring-flowering shrubs, sow hardy annuals outdoors and it’s a good time to set up plant supports
TOUGHEN UP TENDER PLANTS
Plants nurtured indoors or under glass can’t be planted outside straight away. Sudden exposure to cold and wind could check their growth. Instead, toughen them up by hardening them off. Place them outside in a sheltered spot for a few hours during the day then bring them inside. Gradually increase the amount of time they spend outdoors. In 10-14 days your young plants should be ready to plant outside. Bring them indoors if heavy rain or hail is forecast, and cover them with horticultural fleece if it’s chilly.
DIRECT SOW HALF-HARDY ZINNIAS
Many half-hardy annuals can be started off in pots indoors, ready to plant out at the end of the month, but zinnias are an exception. These fabulously colourful half-hardy annuals don’t like root disturbance and often sulk if moved, so the best way to grow them is to sow directly into the soil.
Zinnias originate from Mexico and love heat, so wait until the ground has warmed up in mid to late May before sowing. Cover the soil with a cloche or plastic sheet to warm it up first. Sow in a sunny spot with well-drained soil. If you have clay soil, try them in raised beds or large containers.
Plant out sweet peas
Prepare for planting out sweet peas now, by putting their supports in place. Use 2.5m tall bamboo canes or sturdy hazel bean poles.
● Push a circle of five or six canes into the ground about 15-20cm deep, then gather them together at the top to secure into a wigwam with twine.
● Once you have bushy sweet pea pla
