During the dormant period, many plants succumb to frost or to cold, excessively wet soil. Leaves may become frost-bitten and roots can rot. So it’s important to protect your plants before first frosts strike, to ensure a good display the following year.
The level of winter protection required depends on where you live and how exposed your garden is. In sheltered city gardens, you may get away with not protecting tender plants at all. However, if you are going to experiment, do pay attention to weather forecasts – don’t get caught out by a sudden hard frost.
For general protection of your garden apply a layer of bark compost or mulch 5cm (2in) deep around herbaceous perennials but use grit around the plants themselves. This will stop moisture collecting and rotting the stems while the mulch will keep them warm. The mulch will also help by breaking down over the winter months, adding organic matter to the soil and improving drainage. Also, as you prepare your plants, take cuttings as you go. This will be your insurance policy, in case plants don't survive.
Plants such as echeverias will not withstand any frost at all. So they need to be transferred into grit to stop the roots of the plant from rotting when dormant. Take cuttings by removing leaves from the bottom of the rosettes and simply put into seed compost and wait for roots to form.
Store your succulents in a mini green house in a sheltered spot against a wall. You can make your own mini green house by building a wooden frame with shelves and lining it with bubble wrap. This will keep the plants warm and dry; ventilate them each morning to stop moisture building up by opening up the green house .
Use straw and chicken wire to insulate the trunk of tree ferns. Wrap the chicken wire around the trunk leaving enough space to add a thick layer of straw. The straw, unlike bubble wrap will allow enough ventilation through to keep the trunk warm. Bubble wrap or plastic allows moisture to build up around the trunk, leaving the plant prone to rotting. Leave the fronds on as they will protect the crown over winter. Don’t worry if fronds turn brown after frost or snow – you can cut them off in spring once the new ones start to unfurl. If you feel the plant needs more protection, stuff the crown with straw as well just before the first frost. Don’t do this too far in advance as it can encourage new vulnerable growth.
Tropical plants, such as bananas need to be well protected. Remove the leaves and side shoots to leave the trunk or stem. Space tall wooden or plastic stakes around the plant and push into the ground. Place the stakes far enough from the trunk so that a thick layer of straw can be added all the way around the trunk. Then wrap a willow screen around the outside of the stakes and tie this to the stakes with string. Do this for the whole height of the trunk. Finally pack the gap between the trunk and the willow screen tightly with straw.
Protect individual alpine plants with a piece of glass or plastic over the top. Support the glass or plastic with wire legs or raise it up onto bricks. Make sure it is not able to blow away. To protect a whole bed, build a wooden frame and place a sheet of plastic or glass on top. Leave the sides of the frame uncovered to allow plenty of ventilation.