Overwintering Plants Indoors

Now I know that there are more enthusiastic gardeners out there right now than I am. I’m about to enter winter-sleep mode and simply think about gardening for a few months rather than actually do anything.

But I know there are determined folks who intend to garden all winter long in their windowsills greenhouses, basements and back bedrooms. And I want to thank all of you because you’re probably going to be reading my columns every week instead of those slackers, like me, who intend to stop gardening for a bit and take a break. It’s good to know that folks like you keep on going to shame folks like me who can’t imagine working away all winter long. So in celebration of your somewhat-crazed behavior, let me pass along a few tips you might find useful. I used to pay attention to this kind of thing when I grew way too many plants as well.

Really! Clear off the Insects Now

The first thing is to make sure that your plants are clear of any insects and problems. Do it now. You really do want to take that insecticidal soap spray and start spraying the bejabbers out of all your plants. Do it weekly if you see any pests on the plants. Trust me on this one, there are hitchhikers such as spider mites or aphids that have come indoors with all your plants and they’ll lie around for the next month or so just building up energy and then wham! – you’ve got a serious infestation on your hands. So just assume you have some problems and soak those plants.

Spray both the tops and bottoms of the leaves until the spray runs off (do this on plastic sheets as you’ll have soapy water everywhere otherwise) the leaves and make sure that all the leaf axils (where the leaf joins the stem) are soaped up. If you have stems that are a bit old and barked-over, then ensure the spray gets into all the cracks in the bark where the pests like to hide. Be as thorough as you can with these initial sprays because you’ll save yourself a lot of grief later.

Water and Feed or Die

The second thing to consider is your watering and feeding routine. I’m a great believer in feeding plants if you want them to grow. But at this time of year, when the plants are taking a bit of a rest with the lowered light levels, then I’d back the fertilizer off to half or even quarter strength. And I feed every two weeks instead of weekly. So the plant is still getting a bit of food when I water but not much. Enough to keep it ticking over but not grow like stink. So do cut back on the feeding but don’t quit. Too many folks just quit feeding and then wonder why their plants are long, leggy and pale green in another few months.

The pale green comes because not only is there not enough food, there’s not enough light to grow plants. That is unless they’re acclimatized to low light levels and have never been outdoors in the summer. Those are your problem.

My advice concerns those plants that have come indoors with us to try to overwinter alongside us. Those poor outdoor plants are wondering what in heck happened to them with the lowered light levels. They’re struggling.

Hey – it’s your choice here

So you have several choices here. Those who are truly plant-berserkers should consider getting grow lights and keeping the light levels high enough so the plants don’t stretch and go pale-green. Keep the grow lights within inches of the top of the plant and you’ll be amazed at how the plant responds to this light-love. Those who simply want to keep the plant alive for the winter can find a nice sunny windowsill in a cold room somewhere. The cold temperatures will help slow the plant growth down so it doesn’t require as much sunlight. It will still stretch out but not as much. The worst thing you can do is put them in a warm room in north-facing or dark windowsill where the temperature makes them want to grow but the light levels aren’t enough to give them the energy to grow. You’re almost better off killing the plant outright rather than torturing it all winter like that.

Broken Record on Watering

And I’ve written so many times about only watering when the soil is dry that I’m starting to sound like a broken record, even to myself. But that’s important in the winter. Touch the soil and if it’s dry, then water. If it’s wet, don’t water. There’s no finer way to learn how to garden than to have to watch the winter water needs of a bunch of plants. They’ll all be different with their own needs.

Better Growing Temperatures

I always found that keeping overwintering plants a tad on the cool side gave me a much better looking plant than if I tried to keep them at the optimum growing temperature. Now those houseplanty-type things really need their warmth but outdoor plants you’re overwintering (remember, I’m not overwintering a darn thing) do much better if you keep them cool. Where optimum temperature outdoors might be 22-24C (mid-70’s F) optimum indoor temperatures for winter are better off around 14-15C (low 60’s F). These cool temperatures slow down growth and allow the plant to rest a bit. And you want it to rest, even though it is an outdoor annual, because about February when the light levels are coming up, you’re going to push it into growth to take slips and cuttings to get even more plants to overwinter for next year. But how to do that is another column entirely.

Enlightenment Comes to Few

Now of course, I’m much more enlightened about such things. I believe in visiting the plants in their native Southern habitat rather than trying to brutally force them to grow in mine.