Overwintering plants

These are some of the plants in your garden that may need overwintering.

1. Tender perennials

Some perennial plants (plants that live for more than a year) are known as ‘tender’. This means they will not survive outside if the weather is frosty. Examples are:

• Cannas
• Dahlias
• Pelargoniums

You may need to move these plants inside during winter. See below for advice.

2. Plants that can get frost damaged outside

Many plants can survive outside, but will benefit from some extra protection. These include:

• Tree ferns
• Most perennials that are growing in the ground
• Some shrubs, such as fuchsia and fatsia

3. Plants in containers

Container plants almost always need some extra support in winter. This is because containers are more likely to get wet and freeze. See below for advice.

4. Winter crops

Some food crops have varieties that can survive outside in winter. For example:

• Winter salad
• Onions
• Garlic
• Carrots
• Broad beans
• Herbs including mint, sage and parsley

Be aware, most of these are not really growing in winter, especially when the temperature drops. In general, they are just sitting waiting to grow in spring when the ground warms again. You may need to keep an eye on these during the winter to make sure they are not getting too wet or damaged.

You may have planted some food crops earlier in the year, like leeks, kale and Brussels sprouts, that are ready to eat in winter. These simply need harvesting, not protecting.

5. Tall plants

The advice used to be to cut back and tidy perennials before winter. Now, for many plants, we suggest you leave them. Seed heads and dying stems make places for wildlife to shelter in winter.

So, leave your hydrangeas, sedum, rudbeckia and grasses alone.

Some very tall plants, like hollyhocks and cardoons, could be cut back a bit if you have a windy garden.

6. Indoor plants

When we think about overwintering, it's usually the plants outside that come to mind. Some plants inside will benefit from some extra care ahead of winter.

If you are growing chillies, pick off the fruit and leave them somewhere light and bright inside. They should grow again in the spring.

Some very tender perennial plants, such as cannas, dahlias and pelargoniums, may not survive winter outside. These can be carefully lifted from the ground and stored somewhere warm and sheltered, like a greenhouse or garage.

Some care is needed when lifting and storing. Each plant has slightly differently needs. You can search online for guidance on lifting and storing your particular plant.

You may not have to lift and store these plants. If they are growing in a warm, protected spot in the garden, for example, they may be ok. Or, if you have a lot of them growing you may decide it is not possible to lift them all. In this case, add a thick layer of mulch around the plants and leave them.

We can protect some plants with a horticultural fleece. This can be use in different ways.

You can wrap fleece around some plants, like tree ferns.

Or, you can use it more like a blanket to keep out cold and wet (see below).

If you buy very good quality fleece, it should last 2-3 years use.

Many of the plants in our garden will benefit from extra ground cover during winter.

One of the best ways to do this is apply a thick layer of mulch over your flower beds in autumn. Mulch is any sort of organic matter, for example well-rotted stable manure or good quality compost. When adding mulch, pay special attention to getting it around the base of plants. This will help protect their roots from frost. Mulch also protects the soil from wind and rain damage.

Many food crops that grow or survive through winter will also appreciate a layer of mulch, such as winter salad and onions.

You could use horticultural fleece to cover the ground around some plants – a little like a blanket. Another alternative to this is straw. Straw is also biodegradable, so better for the environment. If using straw, put it in place when the weather is dry and calm. It may blow around if you try to put straw in place on a windy day. This is a popular choice, as the name suggests, for strawberries as well as carrots.

Containers and pots can really suffer in winter. They may stay full of water after heavy rain. If the weather is very cold, they can then freeze completely.

A good way to protect plants in containers is to lift the containers a little off the ground. Putting them on broken slabs, pot feet or upturned pots can help avoid some frost damage.

Think about where your containers are positioned. If they are somewhere cold and windy, try moving them to a more sheltered spot over winter.

If you have food crops growing during winter, you may need to think of giving them some extra protection.

Many salad crops, such as rocket, winter lettuce and winter spinach, will need some cover. A few can grow outside in sheltered positions. Check the seed packet for advice.

Onions are growing underground, so have some natural protection. A good, thick layer of mulch can be helpful.

Overwintering carrots will benefit from a layer of straw, or a cover over them.

Broad bean varieties that you sow in late autumn are usually very good at surviving the winter. If it is very cold, some fleece, straw or a cloche will help to protect them.

Some herbs can overwinter outside, including mint, parsley and rosemary. Add a good layer of mulch if they are in the ground. You can still pick herbs from them during winter, but try not to leave the plant too bare.

If you have a greenhouse or polytunnel, these are great for winter protection for your crops. There are also less expensive alternatives. You can find low growing polytunnels, which are less than a metre high and wide. These are cheaper than full sized tunnels. You could also put very large plastic bottles over salad crops. The larger the bottle, the more you can grow underneath.

If your garden is not sheltered, or you do not fancy looking after crops outside in winter, you could grow indoors.

Herbs and microgreens are great to grow inside in the winter.

Soft herbs such as basil, parsley, chives and chervil should grow well near a window that gets good light. Grown in margarine sized containers they can be harvested young within 4-6 weeks.

Microgreens are also good to experiment with. They will germinate and can be harvested 2-4 weeks after sowing. Have a go at successional sowing to provide a supply throughout the winter months.