May 2015 in the garden

Glynn SmithBy Glyn Smith Head Gardener at Erddig Hall National Trust Garden

Despite a little rain at the end of last month, the garden here is extremely dry. Over the next month we will be keeping the garden tidy and lawns mown. There are lots of new plants that we have been growing over the winter that are ready to be planted out too.

Sweet peas that we have raised from seeds and other hardy plants are being planted into the borders and spaces. Make sure plants are hardened off well before planting them out, we are still getting sharp frosts overnight, and water them in well. Add a little fertiliser when you plant to give them a good start.

The greenhouses and cold frames at Erddig are full to bursting with young bedding plants, that will be planted out into the flower beds later in May, once our spring display of violas and tulips have gone over. Really tender plants, like begonias or petunias would be badly damaged by frost, but antirrhinums and pelargoniums are a little hardier. Hardening off is when plants are slowly subjected to cooler conditions, before trusting them to the weatherman. The usual way is to put them into a cold frame. This can be fully ventilated in the daytime, closed at night, or propped open a gap as they get used to cooler conditions. Look out for slugs and mice though, as they can easily damage young seedlings.

Many vegetable plants are hardy, but tomatoes and cucumbers need protecting. Some outdoor sown vegetables and salads may need thinning out. Don’t waste those lettuce seedlings, they can be planted out to give a later crop. It is not too late either to sow hardy annual seeds directly where they are to grow.

Tomato and cucumber plants are in the garden centres. They can be planted in the greenhouse now, or grown on in pots to plant outdoors later.

As their shoots emerge, Potatoes should be earthed up. This protects them from late frosts and the potatoes will grow in the dark. Green potatoes that develop in the light are poisonous.

If you have not fed your lawns yet, wait until there is some rain to wash it in. Applying fertiliser to the lawn in dry weather can burn it. Time too to consider controlling any moss, by raking, or with a moss killer.

There are lots of young herbaceous perennial plants in the garden centre now to make new beds or to fill gaps in the border. Stake tall growing herbaceous perennial plants now whilst they are still small and don’t forget vegetables, like peas and beans, may need support too.

As early spring shrubs, like forsythia, finish flowering it’s time to prune them.
Later in the month, the spring bedding can be stripped out and composted. Tulip bulbs can be dried off in a shed and daffodils healed in a corner of the garden, or planted in natural lawn areas and borders.

Look out for pests and diseases. Apply a preventative fungicide spray to roses and other plants before you see the diseases. Mildew and black spot will become evident soon. Look out too for aphids and slugs too.