One of the pleasures of gardening is growing plants from outside your hardiness zone. There are many trees and bushes that will grow happily for most of the year, but in winter your own location is just too cold. The way to enjoy these plants is by growing them in pots and providing some protection during the coldest months. By doing this gardeners in the north can enjoy lemons, oranges and other citrus, fig trees, camellias, and many other attractive plants that would not survive being left in the garden all year round.
In other blogs we have looked at how to do this, what containers and soil to use, where to locate the plants and care for them. Since winter is just beginning to take hold, this seems like a good time to concentrate on what is for many gardeners the most difficult part – carrying these plants through the winter. We will give you some tips of the best locations to do this, and on how to care for your plants in winter, so that they are healthy and ready to go back outside in spring.
Tips for Overwintering Patio Trees:
- Keep deciduous trees as cool as possible – they are best stored in a cold, but frost-free place. They don’t even need light.
- Give evergreens plenty of light – good light is the key to keeping them growing well.
- Cool, well-ventilated spaces are best – lower temperatures, and fresh air, will keep your trees healthy.
- Keep watering to a minimum – only water when the soil is almost completely dry.
- Keep a close eye for pests – if you catch them early they are easy to control.
How to Overwinter Deciduous Trees
Although most of the tender trees grown in pots are evergreen, some lose their leaves in winter. One of the most common tender trees that will do this is the fig tree. Growing your own delicious fresh figs is a real treat, and a big reward for the simple work of growing a fig tree in a pot. Figs do very well in pots, and often produce more fruit than they will when growing in the ground. They are relatively hardy, but they do not like frost. As the winter gets colder the leaves will yellow and most or all of them will fall.
It is a mistake to bring these deciduous tender trees into the house. They will do best in a place that is frost-free, but cold. Temperatures around 40 degrees, or even as low as 35 degrees, suit them best. Since they have lost all their leaves they do not need light, and they can be stored in any outdoor shed or garage. As long as it does not freeze inside the space, your trees will do very well simply left there for the winter. Give them the minimum water – just enough to keep the soil barely damp. Once there is no danger of frost outside, put them back outdoors as soon as possible, while they are still dormant. If you keep them indoors, the leaves will continue to grow, but the flowering and fruiting cycles will be upset, and they will often simply grow leaves all year, or flower at odd times.
Keeping Evergreen Trees Happy Indoors
Give Them Plenty of Light
There are two ‘keys’ to keeping your evergreen patio trees happy over winter. The first is to give them as much light as possible. If they have been growing outdoors, the light will have been bright. Indoors is much, much darker, so choose a sunny, south or west facing window and place them close to, but not touching, the glass.
Even in a bright place it will be darker than outdoors. Plus, the winter light is very low, so it is common for plants to lose some leaves when they come indoors. This is normal, especially for plants like the Weeping Fig Tree, which almost always lose a few leaves when they are moved around. Citrus trees too will lose leaves when brought indoors. Don’t panic, and don’t start watering heavily, or moving the plants around even more. Choose the best spot you have and go with it. After a while you will see that no more leaves are dropping, and if the location is bright there will still be a respectable number left. Even if many leaves are lost, trees will quickly recover once they are back outside in spring.
Keep Them Cool
We like to keep our homes warm in winter, but your trees, which are more-or-less dormant at this time, prefer it cooler. Temperatures around 50 degrees are ideal, rather than the 65 to 75 that is common inside most homes in winter. If you have cooler rooms, or colder corners, choose these places for your plants. The cooler the better. This also connects with the timing of bringing your trees indoors. The ideal time is when the night temperatures are about the same as your house at night, but also above 50 degrees. The same applies in spring – move your trees outdoors when the night temperatures match up roughly – and once any danger of frost has passed.
A good air-flow is helpful too. If you can open a window nearby if the day is warm, your trees will thank you for it. Be careful that you don’t do this when it is near or below freezing outdoors, as the cold air will easily damage them and cause leaves to fall.
Keep Watering to a Minimum
In winter, when the light levels are low, most trees, even tender ones, are dormant. So they do not need very much water. It is best to let them become almost completely dry between each watering, so that they do not begin to start growing prematurely, and to protect the dormant roots from rotting. This is made easier if you have grown your trees in clay pots. These dry out more quickly, and so your tree will not be sitting in wet soil for several weeks, which is never good. Don’t try to just give small amounts of water. Instead, water thoroughly, and then leave your tree completely alone until it the soil is dry. Then water thoroughly again.
Watch for Pests
Trees outdoors are protected from pests by natural predators, which can be other insects, or birds. Indoors, pests can thrive and quickly spread to damage your plants. Keeping them in a cool, airy place is your first line of defense. The hotter and drier the air, the more likely pests are to develop, especially pests like spider mites. These look like powder on the leaves, and can sometimes make very fine webs around the branches. The air inside our homes is often very dry, with central heating, so placing a humidifier near your plants will keep the air damper, which they will like. This will help reduce pests, and so will regular misting. Keep a spray bottle near your tree, and when you pass by, give it a quick ‘poof’ or two of water.
Regularly check the stems and leaves for any fuzzy, white clusters, or hard, scale-like growth attached to the stems, at the leaf joints, or on the underside of the leaves. These scale insects and mealy bugs can spread quickly. If you catch them early they can be removed with a cotton bud dipped in alcohol, and your trees will be as healthy in spring as they were in fall.
If you follow these simple tips, you will find it easy to over-winter a wide range of tender trees, and enjoy foliage, flowers and fruit from beautiful and interesting trees that cannot spend winter outdoors in your area. Widen your horizons, and start growing tender trees – it’s a lot of fun!