It hit -14° F last week. The coldest I have seen in western MA since becoming a farmer and paying attention to how winter weather impacts the ecosystem. Luckily, we have over a foot of snow helping protect the plants. Snow is amazing mulch!
In Winter, many plants enter dormancy - a period where they stop growing aboveground, conserve energy, shed leaves as needed and rely on stored sugars to survive the winter.
About 1/2 of our field is planted in medicinal perennials from elderberry to marshmallow to lemon balm and anise hyssop.
For most plants we do minimal care for them in the Fall and they reliably come back each Spring. Some years there is at least one crop that doesn’t make it through the Winter. There are many variables - age of the plants, winter weather, garden orientation/layout and how the plants were tended to in the fall.
Perennials are plants that come back year after year in our region. Some tender perennials are more temperamental in our climate and are more likely to be the ones that don’t return come Spring.
Many of the medicinal plants we grow - like ashwagandha and tulsi vana, are perennial in their native climate in India, but act as annuals here. It would require a heated year round greenhouse to keep those plants alive year round.
After 13 winters, here are key practices and tricks to helping perennials survive the winter in our gardens:
- Choosing appropriate plants for our cold climate - zone (5b-ish). For example, the English Lavender variety that we grow - ‘Hidcote’
- Plants in pots (unless they are super cold tolerant) should come inside for the winter, or be buried in their pots. When potted plants are above ground their roots are exposed to cold temps with minimal protection
- Avoid fertilizing in the fall. Fertilizer encourages the plant to go into growth mode, and new tips are fragile
- Don’t cut back plants in the fall with green growth (or wait until late Fall). The leafy tops can act as a form of protection for the plant crowns. And if you cut back in earlier Fall it can encourage the plant to start producing new growth in late Fall (which is typically fragile and costs the plant important resources). It also robs the plant of its opportunity to photosynthesize until it goes into dormancy
- Likewise, if we have harvest a lot from a few plants all season long, they might not have stored up enough energy to survive the winter and thrive the next season. We are mindful about this especially in late Summer, and choose to harvest from only some plants and not all
- Chop back dead woody growth (like elecampane stalks) in late Fall or whenever the stalks are clearly dead. Even better - leave stalks and seed heads up all winter (thinking about you, echinacea) to feed the birds and act as pollinator habitat for insects
- Mulch around perennials with a layer of tree leaves. The mulch protects the plant crown by keeping the temperature more consistent around the base (less fluctuating of freeze and thaw). In the Spring, the mulch can help prevent early weeds, and increases soil organic matter. Make sure to rake off any leaves in the Spring that might be preventing new growth from reaching sunlight
- High tunnels (unheated greenhouses) can protect plants from excessive wind. Our rosemary has survived in our tunnel for years, despite having a stated tolerance of around 18 degrees.
- Planting directly next to a building can help tender plants survive as the building will retain heat in the surrounding soils
Are there any other tips I’m missing? What works for your garden? I’d love to hear - let me know!
While Fall plant care feels far away, these tips can help you plan ahead in how you think about the garden from a full year perspective, including taking into account perennials vs annuals as you map out your garden.
Key for right now is choosing bio-regionally adapted plants like we offer in our Nursery.