How to winterize your plants

hivernage plantes

So you splurged and treated yourself to a eucalyptus tree, an oleander, a mimosa tree, a lemon tree or an olive tree? Here is how to protect these plants over the cold season.

Cold-vulnerable plants are usually trees and shrubs, as well as certain flower bed plants. When purchasing your plant, check the label to see what temperatures it should be able to withstand. Some plants, where when winters aren’t too cold, will simply love to wear a few extra “clothes”, while others will have to be uprooted and moved to the cold greenhouse.

Winterizing plants, the right things to do

“Winter is prepared in fall” is what famed garden masters Brigitte Laouge-Déjean and Denis Pépin advise. They’ve authored a book in French that hasn’t yet been translated to English. Even before the first frost spells hit, in October for example, start getting your equipment ready: this is what you’ll need to protect all parts of the plants: roots, trunk and leaves. Frost won’t win!

For hanging plants or plants in containers, wrap the pot in a large cover and/or bubble wrap. Thick horticultural fleece also does the trick, that’s what it’s designed for. Another option: bury the pot!

winterizingFor both hanging/potted plants and those planted in the ground, build up a layer of mulch around the base: you have a variety of insulating mulch materials to choose from, like straw, peat, flax straw, leathery plane tree leaves, evergreen oak or silverberry, and even ferns or conifers branches. “Proscribe from this list any materials that retain water […]. Adequate materials are those that are and will stay dry.” This is the setup both experts recommend: “Place a few stones or fist-size rocks around the base to provide for ventilation; on top of that, spread the material you’ve chosen, trying to trap air pockets inside, so don’t press it down. Make the layer about 2 inches (5 cm) thick. It’s important to not press it down. To hold this all in place, add a square of horticultural fleece in a simple or double layer, weigh it down with 4 large stones.” And they add: “It’s also quite easy to protect small shrubs with an old plastic bag, piece of burlap, or a UV-treated polypropylene winterizing fleece. Even carton/cardboard from a delivery box can be filled with wood chips. Gather the branches of the shrub to tie them into a ball, and wrap the entire plant from stump to tip with straw, hay or leaves. Bring the sac down to engulf the plant, or wrap the plant with the roll of winterizing fleece cut to size.”

Orange tree, winter garden for the most fragile plants

orange tree greenhouseSome plants like bougainvillea, banana trees, oleander, kumquat or abutilon would tolerate neither a cold winter outdoors, nor a hot stuffy winter inside the heated indoors of a house.

Here’s the solution to this conundrum: Bring them to a cold greenhouse, a garden shed with windows, windowed cellar, or an “orangerie” if you even want to use the poetic word for this, around mid-October. What’s important is that it must be cool but never freezing, well-lit and well-ventilated. Just as for outdoor plants, limit your watering to as little as you dare to ensure the roots stay intact and don’t rot.

As soon as temperatures rise above 40°F (5°C), take them out for a spin but keep an eye on the weather, and bring them back in if freezing might occur.

Further considerations on how to winterize your plants

winterizing plant“Snow tends to protect certain plants like perennials. What is fatal is alternating days of freezing and thawing, as well as windy settings”, adds Brigitte Lapouge. However, “don’t protect your plants too early in fall, or snails and slugs will wiggle into your protective cocoon […]. What’s best: cover it all just before the ground freezes. During winter, make the best of a nice, warmer day to open the packages up and renew air circulation, to eliminate moisture most of all. And then… in spring, remove your protective casings as soon as possible to let the ground warm up.” Lastly, another tip is to lather the trunks of very young trees with clay to protect them from splitting open during frost or during brutal freeze/thaw cycles.

For more tips, try to get your hands on Brigitte Laouge-Déjean and Denis Pépin’s book, “Aménager et fleurir son jardin” [A flowered and well-set garden], hopefully someone can help you get the gist of it in English. Printing house “Terre Vivante”.

Claire Lelong-Lehoang

Image credits: Winter protections 1 and 2: ©Hcast Fotolia Hiverscratch and winterzip : ©Nortene