Cold Climate Gardening

Not too long ago, a reader emailed me and asked,

I bought some hostas and dwarf bleeding hearts to plant. Shortly thereafter I hurt my knee and I can’t go out there and plant them. They are all planted in one gallon plastic pots. How can I safely winter them? If I put them in my garage they will still freeze.

You may have plants in containers that should have been planted, but weren't. How do you winter them over?

It is the roots you are worried about freezing. The rule of …

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Most herbs taste much better fresh, and rosemary is no exception. That’s why every winter I try to keep my rosemary alive in a pot inside the house. Rosemary is not reliably hardy north of zone 7, so while southerners can grow this in the ground and watch it take on shrub-like proportions, we cold climate gardeners must bring it into our houses and attempt to give it the equivalent of a southern winter indoors, or it will never really get big enough to harvest from regularly.

It’s not easy, let me tell you. More than one northern gardener has finished the winter with a dead rosemary plant.

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Improvisational Container Planting
I am pretty lackadaisical when it comes to container plantings. I have three window boxes hanging on the porch fence-cum-railing and a rusting metal washtub that I found in the barn when we moved in. I never really plan or purchase plants for these containers. I count on something showing up due to the kindness of friends or excessive seed sown, and then I try to make it work. Let’s call it improvisational container planting to give it some credibility. (Click all photos for larger–and sharper–image)

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I don’t plant/dig/plant the rosemary plants I winter over–I feel it is too hard on them to repeatedly re-establish. So I keep them in pots, large enough for them to be comfortable in and small enough for me to winter inside feasibly. And carry! This also allows me to indulge in pretty pots for the porch. To harden them off, I start trooping them in & out about now so they spend some cool rainy days outside, then brighter sunny ones, then maybe not bringing them in overnight after a week or so. But as we can have sharp frosts (20’s or less) right into June I never put them farther than an arm’s reach from …

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Correction to the rosemary hints. They can freeze–just not way deep like you’d get outside. I think something like 10F is the limit, maybe 15? Does your porch get colder than that? (Prescott AZ where I saw the planters full certainly sees that cold in the winter. They have some snow now.) And keep the plants on the dry side.
As to germination requirements, the wonderful pages from Tom Clothier and Norman Deno’s books are huge, HUGE resources and I wouldn’t be without them. I am always finding some lovely thing I want that won’t germinate easily and they are my two best places to look.
Garden chores for today: snowshoe …

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Kathy, if you want to keep rosemary happy in the winter, keep it cold & bright (as if it were having a milder winter than you are!)–I either keep it on a barely heated sunporch so it doesn’t go below freezing or above 50, or against the coldest window in a cold room. They seem to need about 6-8 weeks of this type of cold, and probably short days/long nights to initiate flower buds, so natural lighting is best. Last winter’s cuttings, now in 4″ pots, are all blooming as well so I think it is conditions more than age that favor bloom. Interestingly, different varieties are more precocious than others–I have an upright one that didn’t …

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