Protect your plants in winter

For us, winter means hot chocolate, snowball fights, and reruns of *Home Alone*. But for our plants, it's much less cheerful. This dreary season, with its cool temperatures and heavy rainfall, can be fatal to them. Here's how to protect your favorite plants from the cold, frost, and dampness.

What to do when the temperature drops below 0 degrees? Photo by Mustang Joe (Source: Flickr)

Which plants need protection in winter?

All plants have a hardiness limit—a temperature below which they cannot survive. For tropical species, the hardiness threshold is around 10 °C—a figure well above typical winter temperatures in Europe. That's why, in our latitudes, Monstera, Alocasia, and Calathea are grown as houseplants. Conversely, certain rhizomatous plants, some perennial flowers, and trees are more cold-hardy. For example, asters and bletilla striata hyacinth orchid can withstand temperatures as low as 15 degrees below zero.

In theory, all plants should be protected. In practice, the list depends on where you live. If you live in Provence, you can let the hardier species fend for themselves. But in Alsace and the North, most varieties need help to withstand the cold and frost.

Falling temperatures aren't the only danger plants face between November and March. Rainfall and humidity can also spell their doom. This is the case for agaves. They can withstand temperatures as low as -20°C, provided their roots stay dry.

When should you protect your plants?

To avoid unpleasant surprises, it's best to plan ahead. Photo by Sarah (Source: Flickr)

It's best not to wait until the last minute. Sometimes, just one night of frost is enough to decimate flower beds and rock gardens. To avoid disaster, we recommend planning ahead and protecting your plants before the cold sets in. Plus, taking action early on limits the thermal shock for the plants. They can adjust more easily to their new environment.

At Monstera, we're a bit like a cross between Nicolas the Gardener and Évelyne Dhéliat. We know the hardiness zones for different species and the latest weather trends. So we're working to let you know when it's time to protect your plants from the cold. This feature will be available starting in 2023.

Protecting Plants from Cold and Frost

There are many tips for protecting delicate plants from frost and cold in winter. Depending on the plant's hardiness, how it's planted (in a pot or in the ground), and your resources, choose the method that works best for you.

Bringing Plants Indoors

South of the Loire River, cacti and succulents spend much of the year outdoors. When temperatures drop, you can bring them indoors. Find a spot for them that gets plenty of light but is sheltered from direct sunlight. On a shelf just behind a picture window fitted with a sheer curtain or in front of an east-facing window, they'll enjoy maximum light without any risk of harm. While they're indoors, water them sparingly. Generally, monthly watering is sufficient.

Other plants with low hardiness, such as Mediterranean shrubs, cannot withstand either the harshness of winter or the heat from our indoor heating systems. Ideally , bring them indoors to an unheated but well-lit shelter. If you have a sunroom or greenhouse, move your Lemon tree, oleanders, and bougainvilleas there before the first frost. Grouping the plants together also allows them to help each other and stay warm. But don't crowd them too closely together either. Your plants should not touch each other to prevent the spread of disease.

Techniques for Protecting Outdoor Plants

Not everyone has a garage with a window or a garden shed where they can store their potted plants when the temperature drops. And this solution doesn't apply to plants growing in the ground either… In these cases, alternative methods can help your plants survive the winter.

Organic mulching photo by JSB (Source: Flickr)

Start by protecting the roots by mulching the base of the plant with organic material. A layer about 10 centimeters thick of fallen leaves, hay, clippings, or straw provides excellent protection against frost and cold. As it decomposes, it becomes a very good fertilizer.

For your rose bushes, in addition to mulching, try hilling. Behind this somewhat barbaric-sounding term lies a simple task: piling a mound of soil around the base of the plant, up to the height of the first branches. Roses aren't the only ones that appreciate this care. In the vegetable garden, hill up peas, beans, and potatoes.

The foliage and trunk should also be protected from frost. Wrap them in a cover or winterizing netting. If you're worried about a severe cold snap, don't hesitate to use several layers and to wrap the pot as well. But covering vegetables and small perennials can quickly become tedious. To save yourself the effort, opt for a winterizing tunnel, which is easier to set up. Have you decided to make your own winterizing cover? Don't use a tarp or plastic sheeting. Since these materials are impermeable to both air and water, they would suffocate your plants. No matter which type of protection you choose, always make sure air can circulate inside.

A tree protected by a wintering cover Photo by Jihad Alachkar (Source: Flickr)

Another tip for keeping potted plants warm: raise their containers off the ground. The stone or concrete surfaces of our patios retain cold and cause the temperature of the substrate to drop. By placing cardboard, bubble wrap, or spacers under your container, you create a layer of insulation and gain a few degrees. Finally, we recommend moving your planters closer to a wall. Protected from the wind and heavy rain, the plants will also benefit from the heat radiating from the house.

Dig Up the Bulbs

Dahlias, gladiolus, and hyacinths require thorough care. The plants must be dug up, and the bulbs stored in a dry, well-ventilated, and frost-free location. You can store them in your basement, garage, or even your laundry room—as long as it doesn't have windows. Light triggers the germination process.

Our tips for protecting plants from excess moisture

The first step in combating excess moisture is to reduce watering. During the winter, plants need less water, and rain is generally more than enough.

But if it rains too much, take a few precautions to protect your plants. Remove the saucers so water doesn't pool there. It could freeze or cause the roots to rot.

Prevention is key to dealing with excess water. When planting, work the soil in your garden and amend it toimprove drainage. For species most sensitive to moisture, choose a spot at the top of a slope or near plants that absorb excess water during downpours.

Protect Them—Then What?

Now that your plants are sheltered, that doesn't mean you should forget about them until spring.

Even once they're nice and warm, your plants will still need your care. Photo by Marko Kudjerski (Source: Flickr)

Check the soil moisture regularly and water when the potting mix is dry. To prevent the water from freezing, water in the morning and, if possible, on a sunny day. Take this opportunity to air out the winter cover for a few minutes.

If you've brought humidity-loving plants like papyrus and begonias indoors, mist their foliage regularly. The dry air in our heated homes isn't very good for them. However, there's no need to mist the leaves of cacti and succulents. (To learn how to mist like a pro, read our article Should houseplants be misted?).

Finally, be patient. Don't remove all the protective covers as soon as the first rays of March sunshine appear. Frosts can still occur. Once the last cold snaps have passed, remove the winter covers and tarps, put the pots back in their places, and bring your plants back outside. Again, don't rush. After three months in the greenhouse or in your living room, they'll need time to adjust to the light and temperatures.