Over Wintering Tender Plants
As we approach the end of September, gardeners’ thoughts start to turn towards preparing for winter, and particularly, overwintering tender plants. All gardeners hate losing plants to winter cold, so what do you need to do to give your plants the best chance of surviving winter?
1) Know your plants.
Find out how hardy your plants are meant to be. All plants now have a hardiness ‘rating’, telling you what temperature they should be able to survive. So that gives you a starting point for which plants you know would prefer not to be outside in winter. Some obvious suspects for careful overwintering include pelargoniums and geraniums, dahlias, and alpines. You will also know from previous experience which of your plants have not coped well with cold, or perhaps which areas of your garden tend to be particularly cold, and you can take action to protect those plants, or marginally hardy plants in those areas.
2) Move plants indoors or under cover
Any tender plants in pots can be moved indoors as the first frosts approach, say over the next month or so. If you have a greenhouse which you can keep frost-free, or a cool conservatory, those are ideal for plants like pelargoniums. Alpines are fine with cold, but hate winter wet, so they need to be moved under cover, but not necessarily indoors, saving you a bit of space.
Plants like dahlias or begonias have tubers which rot in cold and wet. As soon as the first frosts have blackened the foliage, lift the tubers, and store them somewhere cool, dry and frost-free. In a bucket of sand or dry topsoil in a greenhouse or cool garage is ideal. You can buy suitable sand or soil from compost and topsoil suppliers.
3) Cover and protect outdoors
For tender plants in the ground, you have a couple of options. For perennials, you can provide a thick surface mulch and just hope for the best. If you really valued them, you could dig them up and put them in pots over winter, but it’s a lot of work, and takes up room in greenhouses or coldframes. For tender plants that you really can’t move, such as tree ferns, palms and so on, you can wrap them in horticultural fleece, or even bubble wrap, allowing light through, but hopefully keeping them frost-free. Visit one of the RHS gardens in winter, and you will see large parts of the garden wrapped up against the cold!
4) A word of warning
Even the most experienced and careful gardeners find that despite precautions, they can still lose plants in particularly hard winters, or in a series of hard winters. So harden your heart, but keep your fingers crossed for favourites.