Give Pests the Boot!

Tidying up the garden for winter is a balancing act. On the one hand you don’t want to leave hiding places for pests to overwinter. But on the other you need to ensure that beneficial bugs – including pest predators – have somewhere safe to sit out the cold so they’re about for the next growing season. The advice we’re given to banish pests often has the unintended effect of discouraging beneficials too. So what is a wildlife-friendly gardener to do?

Should I Cover or Expose Soil?

Perhaps the greatest area of confusion lies around whether or not to cover the ground or leave it exposed to the cleansing effects of frost and hungry birds. In general it’s best to follow nature’s lead and keep soil covered during winter. Lay thick mulches of garden compost, leaf mould or other organic matter over the surface to stave off soil erosion and sustain beneficial soil dwellers such as earthworms and ground beetles.

In areas of the garden where pests have been a problem a good compromise is to delay laying down organic matter until midway through winter. Or rake back mulches during cold snaps to temporarily expose ground. Raking or lightly forking the soil will help to reveal lurking grubs both to frosts and insect-eating birds, helping to dent their numbers before spring. This is a particularly good technique to use around fruit trees, bushes and canes, where leaves of any plants that were affected by pests or diseases should also be raked up and removed.

To Weed or Not to Weed?

When it comes to weeding, the best course of action depends on the type of weeds you’re dealing with.

Late autumn and early winter is a good time to get rid of perennial weeds, whose growth should hopefully have slowed enough for you to finally catch up with them! Be thorough and remove all of their roots too, otherwise they’ll just regrow again.

While weeding clears growing areas ready for springtime sowings, don’t be too hasty. Annual weeds like bittercress and deadnettle can be left to provide insect habitat and protect the soil over winter, before hoeing them off in the spring. Just be sure to remove them before they produce seeds.

Where possible, seedlings of self-seeding flowers such as calendula or nigella should be left to attract next season’s beneficial bugs because they’ll flower earlier than new sowings. And if you can leave a clump of nettles untouched in an out-of-the-way spot, they are a great food source for many beautiful butterflies and pest-hungry predators such as ladybirds.

Protect Fruit Trees from Overwintering Pests

The bark on fruit trees offers good hiding places for pests like aphids and scale insects. Once all the leaves have dropped you can apply a winter tree wash to bare branches. This is a natural, plant or fish oil-based treatment which should be sprayed on a windless day to avoid drifting. It will help to control pest numbers while causing minimal impact to other wildlife. but as with all treatments it’s best to only use it if you’ve experienced pest problems on your trees during the previous growing season.

Paint tree barrier glues, or tie on grease bands around the trunks of fruit trees to help prevent damage caused by winter moth caterpillars. The sticky barriers prevent the egg-laying wingless female moths from climbing up into the canopy from ground level. Grease bands work best on trees with smoother bark where moths won’t be able to simply crawl under them, while glues are best for trees with deeply fissured bark.

Clean Greenhouses and Cold Frames

Winter’s a good time for a thorough clean of greenhouses and cold frames. Move everything out and clean greenhouse staging, all equipment and dirty pots and trays too. Leave it to dry while you then clean the glass using water with a little added natural disinfectant or greenhouse cleaning solution. Be sure to get into every corner, crack and crevice, any way you can!

Spaces for Beneficial Bugs

To keep beneficial bugs onside leave the rest of the garden a little wilder during the colder months. Allow grass to grow longer so caterpillars and other bugs can bury themselves into the thatch. Hollow stems and fallen leaves should be left where possible to provide habitat for all manner of insects. Old seed heads give shelter to ladybirds and other pest predators – and food for hungry birds. Cut them back in spring just before growth resumes. Hold off digging in ornamental borders until spring too – and then only if absolutely necessary, so that insects such as bumblebees can sit out the winter in peace.

You can provide additional homes for beneficial bugs by dotting bug hotels – big and small – around the garden, and, as long as you’re not in an area with termites, by creating log or stone piles, which will also prove popular with small mammals and amphibians such as toads.

So tackle pests where they have been an issue, but hang back from being too tidy so the good guys have somewhere safe and secure to bed down for winter. Do you have any tips for booting out pests while giving beneficial bugs a helping hand? If you do leave a comment below and share them!