Winter is the ideal dream time for cold-climate gardeners, but it’s also a perfect time to review good gardening practices and increase your gardening knowledge. For this Winter Review we’ll examine plant hardiness zones.
Plant hardiness zones depict general temperature-range regions. To help avoid gardening disappointments, it’s good to know your specific plant zone. Find the USDA plant hardiness zone/s in your state, then get a closer look by searching by zip code.
If you live in Connecticut, you should not assume a plant growing in one part of the state or region will work in a more northern or southern landscape in the state. On the USDA map, Connecticut ranges through 1 1/2 zones -from 7a in Long Island Sound coastal areas to 5b in the northwest corner.
The same search at Plant Maps shows Connecticut zones ranging from 7a along the shoreline to 5a in the northwest corner. On both maps the ‘a’ designates a slightly warmer and the ‘b’ indicates a slightly colder sub-zone within the same numbered zone.
A closer examination of your specific town, may show you living and gardening on the edge. For instance, the town in which I live, garden, and work is divided into zones 6b and 6a on the UDSA map and into zones 6a, 6b, and 5b on Plant Maps Connecticut map. This means a plant that is borderline hardy in my zone 6b garden may struggle in an open, unprotected section of a garden just a few miles to the north.
You could let these designations make your head spin, but don’t. Plant hardiness zones serve as a good general guide when choosing plants most likely to survive in a region, but choosing a plant appropriate for your zone does not guarantee survival.
This tag for Hakonechloa macra ‘Aureola’ informs this Golden Japanese Forest Grass is most likely to thrive in zones 4 to 8 provided it is also planted in soil, light, and moisture conditions that meet its needs.
When shopping for plants at a garden center, in a catalog, or online it is important to pay attention hardiness zone recommendations. Just because one ornamental grass is hardy to your zone does not guarantee all others are. The same is true for many types of shrubs and perennials – not all varieties are equally hardy in the same zones.
If you crave a perennial hardy only to a warmer zone, say a zone 9 plant when you garden in zone 6, accept that this plant is not likely to survive your zone 6 winter. In plant talk this is a tender perennial. If you must have it then plant it knowing it will die over the winter or find out if it can be overwintered in a pot in an unheated garage or basement.
On the other hand, if you crave a perennial hardy to zone 7, but garden in zone 6, the plant might survive when situated in an area protected from harsh winter winds, if given extra layers of mulch, or if planted near hardscape that tends to help maintain slightly warmer soil temperatures.
Taking such steps is taking advantage of microclimates, which will be the topic of my next Winter Review … stay tuned.