Coddling Your Plants Through an Arctic Winter

By Mike Hellmann
Reprinted from HSCSS Digest
in Winter 2022 CSSA To the Point

This is my 19th year of overwintering succulent plants. Even though this is my third year with a greenhouse, I still have many plants in the basement and throughout all levels of the house.

There are a few key points to remember when preparing to limp your plants through the winter. First is to grow them well to become healthy over the summer so they are better able to overcome the long, punishing season indoors. Proper fertilization, light levels and pest control will give your plants a big advantage when moved indoors.

Second is remembering the fact that you want your plants dormant (except for winter growers) during their stay indoors. Growth at this time is weak and unnatural. Plants need to rest in order to grow and flower properly during the growing season.

We’ll start in the basement, where my desert cacti, euphorbias, sansevierias and most other succulents spend the winter. The exceptions here are the tropical plants that need at least 60 degrees F to survive. Cacti fare better here along with deciduous plants, agaves, bromeliads and most caudiciforms.

Forty-watt fluorescent bulbs on timers illuminate the plants. Since the plants shouldn’t be growing, broad-spectrum bulbs do very little. I’ve kept some cacti in complete darkness for the entire winter with no ill effects.

Watering here depends primarily on temperature. At 60 degrees plus, you’ll have to water more. Try to run temperatures as low as possible, as this discourages winter growth and minimizes the need for water.

It is beyond the scope of this article to go into much detail on what to water and when. As a general rule, I lightly water most succulents and columnar cacti every two weeks and the globular cacti every four. Below 55 degrees, I don’t water at all until things warm up. Cooler temperatures will also reward you with more flowers. Dormancy is a needed rest, and the reward is better plant health and flower production.

Remember to put lights on timers, run a fan around the clock to circulate air, remove top dressing to better monitor soil moisture and use a vacuum to remove dead leaves, cat hair, dead bugs and spider webs.

I keep all my warm-blooded friends upstairs, where the temperatures never see 60 degrees or below. Antplants, melocactus, uebelmanias, ficus, carrallumas and others perch on or next to south/east-facing windows where, when unobscured by fall leaves clinging to the trees or evergreen Christmas decorations hanging outside the windows, there is access to lots of light.

I water the rhipsalis, antplants and other leafies once per week if sunny. The South American cacti and stapeliads are watered biweekly. Keep watch for mites, mealy bugs and scale. They can go from nothing to complete infestation nearly overnight.

No matter where you overwinter your plants or how, you’ll have casualties. Some are inevitable, as certain plants available in the hobby are just too demanding, regarding culture, for most of us to maintain. You can only force or compromise with Mother Nature so much.

For example, my biggest plant challenges come with the tropical stapeliads, such as the hoodias, trichocaulens, pseudolithos, etc. My peat-based mix is most likely the culprit, along with our steamy, amazonlike summers.

If you make yourself aware of the origins and habitats of your plants, you’ll better understand what makes them tick (or die). You can then categorize them by watering needs, full sun or shade, growing season and soil mix. Watering a helter-skelter mix of plants on a bench presents many more challenges than if all the plants on the bench desired a similar level of soil moisture.

One last hint to maintaining a healthy collection is to focus on your favorite groups and what you do well with, weeding out those that present an uphill battle or that have worn out their welcome. For the past few years, I’ve focused on fewer groups to better manage my collection.

This evolution never stops and will always change. It is very tough to have a little bit of everything from all over the globe. Focus on what you like the most and what treats you best. From there, you can grow forever in a plant hobby that shows no sign of getting boring any time soon.