Snippets May 7 2015
    Whether you start your own seedlings or get them from the garden centre, the next couple of weeks can be tricky. If you've got seedlings that have been growing in a greenhouse or under lights, they need to be introduced to cold, wind and even strong sun gradually. The process is known as hardening off. Do this over at least a week before you can be sure you can leave them outside all night, or plant them out. There's no point in planting tender plants out too early, if the soil is too cold, there will be no growth.

    If you do plant out and an unexpected frost threatens, you can use row cover or any light cloth, even newspaper or loosely piled straw, to trap enough warmth to keep the seedlings protected. Remove the protection during the day. For tomato seedlings, you can make structures that stay in place during the day - a plastic bag open at both ends and held up by stakes, or large plant pots with the bottom taken out.

    Trees, shrubs and perennials can be planted out now – but be aware that if you're buying plants that have been in a greenhouse up to the time of purchase, they may be a little tender and need protecting for the first couple of weeks.

    Beware of invasives Beginning gardeners, beware. Some plants can outstay their welcome in a big way. There are many popular ground-cover plants from Europe or Asia that people put in because they spread fast and are perceived as a quick and easy solution. Because they are alien species, they get out of control, are really hard to eradicate when you change your mind, can spread uninvited to your neighbour's yard and can escape to the wild and displace native species, degrading natural habitat.

    These are some of the ones to avoid: Bishop's Goutweed, Bugleweed (Ajuga), Lily of the Valley, Periwinkle (Vinca), Lamium, Yellow Archangel, English Ivy... For alternatives, there's a handy booklet – Grow Me Instead - that you can download.

    Is it dead? This is the time if year we monitor all our plants for those exciting signs of growth that tell us they are emerging from their winter sleep. But if nothing has happened yet, don't despair. I never write anything off until the end of May.