Go Native: Getting Ready for Spring Planting, Do You Know What Zone You Are?
By Emily DeBolt
Sunday, April 22, 2012
Well, it isn’t spring just yet – but the warm temperatures and lack of snow cover this winter sure have me ready to get out in the garden and get planting. The garden magazines and catalogs with beautiful plant pictures are already overflowing my mailbox and they sure can be hard to resist. Now is a great time to be thinking about what plants you want to add to your garden this spring, or maybe even designing a new garden for your property. But remember; when selecting plants for the garden, whether native or not, you always want to keep in mind your site conditions such as sun, soil, and water. You also want to be sure to think about your hardiness zone. If you keep these things in mind, they can help stop you from those impulse plant purchases that may look pretty in the catalog, but just aren’t meant to grow in our area. If the right plant isn’t in the right place, you can have the greenest thumb in the world, but still not be able to make it grow.
Plant Hardiness Zone Maps help gardeners determine which plants are most likely to thrive in a location. Even when gardening with native plants, you have to keep zones in mind. For example New York State covers zones 3-7. So there might be plants native to southern New York zones 6 or 7, but they aren’t for us – since our area is mostly a zone 4 (or at least I thought it was! – more on that in a second).
If you are an experienced gardener, you are probably very familiar with what zone you are gardening in. However, in late January USDA released a new version of hardiness zone maps for 2012. You might think you know what zone you are – but it turns out you might be wrong according to the new maps.
Hardiness zones are based on the average low winter temperature. Zones are divided by 10 degree increments, with a and b subsections for 5 degree increments. In the new 2012 maps many locations across the country shifted and became a subsection warmer. So if you were a 5a you might now be a 5b, and if you were a 4b you might now be a 5a. This new map is based on 30 years of temperature data, from 1976-2005, and was created with new and improved algorithms that took elevation and other terrain features into account. The old maps were based on a shorter and older temperature record, and simpler modeling, so they had become outdated. The new maps are much more accurate for our current conditions.
Another great thing about the new map is that it is also now interactive – so it is much easier to see exactly what zone you are in. You can just enter your zip code and ta-da – the site will tell you what your new zone is! Go to http://planthardiness.ars.usda.gov/PHZMWeb/ and enter your zip code to try it out.
According to the older map that we have been using up until now, the Lake George area was 4b. That means that the average low winter temperature was -25 to -20 degrees F. However the map has changed slightly for our area, and some locations around the lake are now considered 5a, meaning average low temperature of -20 to -15 degrees F. Now this new map has been making headlines in relation to global climate change, but I just want to talk about what it means for gardeners in terms of plant selection.
Whenever you are buying plants for the garden, you want to make sure they will be hardy to your location. This shift means that some of us might be trying out a few new plants in our gardens and see how they do! For example, Inkberry, Ilex glabra, is listed on many lists as hard to zone 5-9. Although well-known native plant expert William Cullina notes in his Native Trees and Shrubs book that if sited carefully, it can be hardy to zone 4. I have been growing Inkberry at our nursery because it is such a great native alternative for many non-native evergreen shrubs used to landscape foundations, such as boxwoods. Even though it has been making it through the winters so far, I have not been growing large amounts, because I was nervous about it overwintering in our area based on the zone data available. Now of course, our climate conditions haven’t changed from last year to this year, but now with the new maps based on more accurate modeling, I have more confidence in this plant for our area.
Take a look at the map and see if your zone shifted. If it did, there may be some new plants that you might want to go ahead and try out this year that you hadn’t tried before. I wouldn’t go out and plant a dozen of something new, but maybe get a few and see how they do. I know I might add some Sweetspire, Itea virginica, a great native alternative to the popular non-native butterfly bush, to some of my own gardens and see how it does. According to the new maps – it should do just fine! But I think I will do some testing on my own first for my own specific site conditions. After all, algorithms and equations are great, but they aren’t Mother Nature!
Emily DeBolt is owner of Fiddlehead Creek Farm and Native Plant Nursery in Hartford, NY. She can be reached at Emily@fiddleheadcreek.com.
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