Winter Care Principles

Short version:

➢ Leave perennials standing or cut them down to 4-8”. Just make sure they don’t flop onto another plant’s crown (the growth center where the plant emerges from the soil).

➢ Mulch is good, as long as it isn’t directly on top of a plant’s crown.

➢ A garden is happier in the winter if you don’t do too much to it. Tidy things up in the fall if you want to aesthetically. But unless plants are diseased you don’t need to remove them from the garden.

Plants are damaged by four things in the winter: Desiccation (too dry), rot (too wet), cold-kill (too cold), frost heaves (too warm/variable). The ideal from a plant’s point of view is a nice consistent snow cover, but you don’t get to control that. So to focus on the things you might be able to control …

To avoid desiccation …

➢ Provide lots of turbulence to decrease wind speeds. This can mean fences, trees, hedges, etc., on the north and west sides of your property. It also can mean leaving perennials standing, or cutting them down to 4-8” or so.

➢ Do not let the soil surface be exposed to air/wind/sun. Mulch is good. So are leaves and cut-down perennial stems. Just leave them in the garden, between the plants. (Birds will also appreciate your leaving flower seeds available in the garden.)

➢ Come spring, I’ll cut the perennials down to 2-3”, to give more space for fresh growth.

To avoid rot …

➢ Make sure that nothing is resting directly on the crown of a plant. Keep mulch at least 2” away from tree trunks. (Always – if a landscaper piles mulch like a cone around a tree trunk, they don’t know what they’re doing.)

➢ An exception is roses. They like to have a shovel full of compost put on their crowns shortly after the soil freezes.

➢ If you have a plant that “needs good drainage,” try to plant it on a slope or a small elevation. (For example, German irises, agastache, chrysanthemums.)

To avoid cold-kill …

➢ Mulch. Leaves, especially but not only shredded leaves, are great. As long as they don’t mat on top of a plant’s crown.

➢ Pay attention to recommended climate zones and the microclimates of your yard. Arlington can be anything from 5a to 6b, depending on the microclimate, so situate your borderline plants accordingly.

To avoid frost heaves …

➢ Mulch to help keep the soil temperature steadily cold. (See a theme here?)

➢ Plant (and transplant) most perennials in the spring, not the fall. They really don’t have time to get rooted in the fall here.

➢ Be wary of doing garden work during January/February thaws. It’s tempting, but it leaves the plants more exposed to the cold air, and it can compress the soil very easily. So keep an eye out for crowns that may be suffocating and rotting. It’s OK to prune sweet autumn clematis as soon as its buds start growing (as mine did last week). But otherwise try to be patient.

➢ Remember that warm spots can be dangerous, since they thaw more frequently. If you have a more delicate or rot-sensitive plant, put it in the colder parts of your yard.

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