Yesterday on Living Today with Mario, a caller from Wisconsin told us she loves lavender so much that she's already placed an order for it - but she wasn't sure about the best way to grow it in her zone 4 garden. When another listener tweeted to say she needed the same information, we had the perfect question for the Homegrown mailbag! Read on for the answer.
Not all lavender is only hardy in Provence. The species most grown there are French lavender (Lavandula dentata) and Spanish lavender (Lavandula stoechas). These are both gorgeous, fragrant plants, but they're only hardy to zone 8 or 9. English lavender (Lavandula angustifolia ) varieties 'Munstead' and 'Hidcote' are hardy and the best choice for cold climates. Fortunately, these make an ideal consolation: pretty, aromatic, and with handsome silver foliage, they're only slightly less voluptuous than their Mediterranean cousins. In fact, the photo above is one of these varieties, and it was taken in New Hampshire.
That silver foliage tells us something about growing lavender successfully: it needs lots of sun and dry conditions. The key to growing lavender in cold climates is not necessarily mild temperature but limiting moisture all year round. Lavender doesn't do well in humid climates and would be perfectly happy just outside the range of your sprinkler system. Cold climate gardeners can take advantage of microclimates in their yard to give lavender the driest, sunniest environment possible: try siting it facing south, in a very well drained area and away from the drip line of trees and structures. If you can use the protection of your home or another building to provide a bit more warmth, so much the better.
Though the tag on English lavender says it is hardy to zone 5, you can probably push the envelope a bit. Gardeners in cold areas with consistent snow cover might have more luck with lavender than someone in a warmer zone with no snow cover. For example, Ellen Hornig, a very knowledgeable plantswoman and owner of Seneca Hill Perennials gave a talk about all the amazing South African natives she can grow in her very snowy zone 4/5 garden that we wouldn't be able to keep alive in our wet-winter zone 6/7 gardens in New York City. Read what she has to say about experimenting with hardiness here, and for even more encouragement, read what nursery owner Tony Avent has to say about it here. Hardiness is a rather fluid construct, one that you should feel comfortable experimenting with because you know your garden better than the USDA or the nursery industry does. Take zone information as a recommendation, especially when it comes to your favorite plants. It's more than worth an educated risk for something you will truly enjoy.
If there's just no way for you to grow lavender as a perennial, then you can easily grow it as an annual, which enables you to enjoy those gorgeous Mediterranean species, if only for a few months. You can try growing lavender indoors at the end of the season, but be prepared for a less than stellar performance. After all, your windowsill in winter is a far cry from the French countryside!
I have one last suggestion - you can always try plastic:
No - not really! That's just my little April fool's joke on you. While plastic lavender will no doubt make it through the coldest winter, you'll miss out on the fragrance and confuse the bees. Better experiment with one of those hardy varieties instead.