This Month in your Garden – May

Let’s mow

The warmth of May and nearing summer sees herbaceous borders spring into life and the grass keeps growing and you keep mowing. Bulbs have faded and you’ll be thinking about those you’re lifting to store, from both the borders and containers. Daffodils you leave in the ground will enjoy a good liquid fertiliser feed now the flowers have faded and let the leaves die back, don’t cut them down.

You can start sowing and planting bedding but keep an eye on the weather for any late frosts, where tender plants may need some protection. Propagate more shrubs by taking softwood cuttings – you can do the same with herbs such as Rosemary.


With frosts passed you can plant out hardy annuals raised under glass and divide spring flowering plants ready for next year. Watch out for greenfly on the roses and use a proprietary spray or mix a little washing-up liquid with water in a spray bottle and you’ll be surprised by the effect. Clear out and prepare containers for summer displays.

A pot or tub can be half filled with a soil-based compost such as John Innes and then topped up with a multipurpose or basket and container compost. Then, in the autumn or next year you just replace the top layer with fresh compost. Always check for vine weevils. If plants, such as busy Lizzies suddenly go limp and die back suspect the grubs may be present. Have a sort through any seed packets you have to see what you might sow and plant out any hardy perennial seedlings grown in March.    

• Plant Dahlia tubers in pots in the greenhouse or on a warm windowsill
• Keep hoeing weeds
• ‘Heel in’ lifted bulbs until the leaves yellow
• Check climbing plant supports
• Tie in sweet peas
• Plant in shade: busy Lizzies, lobelia, mimulus, Senecio cineraria, begonias
• Plant out hardy annuals raised under glass
• Divide Hostas when they start into growth
• Sow winter bedding plants
• Harden off plants raised from seed and cuttings