Oh, The Weather Outside is Frightful

One of the great things about gardening is that you get to engage in a lot of good-natured, completely justified grousing.

Topic No. 1 is, of course, the weather. No matter where you live and no matter what your climate, you will be able to complain about the weather if you garden. At some point during the growing season, it will be too cold or too hot or too wet or too dry or too windy – and you will get to claim that these are the main reasons your garden isn’t looking its best right now.

Even better: If you happen to garden in the greater Washington, DC metropolitan area, you will be able to complain virtually non-stop. That’s because our climate is pretty challenging for both plants and gardeners alike.

As I write this, we’re in the middle of another brutal cold snap, with overnight lows in the single digits in some places and wind chills below zero. Not nearly as bad as many other parts of the country, but cold enough to remind me to pay attention to the hardiness of the plants I put in my garden.

Plants aren’t subtle in this respect: they quickly die if exposed to weather colder than they can tolerate.  Since most of the DC area is in Plant Hardiness Zone 7, that means generally avoiding plants that don’t survive below our average annual minimum temperature of 0 to 10°F.

Unfortunately, Nature does not reward us for making it through a long, cold winter by giving us a few months of pleasant, balmy summer days. Unlike our neighbors to the North, we often leap right into hot and humid summer weather by mid-May – and that weather stays with us well into September.

While the damaging effects of high heat and humidity on plants aren’t necessarily as dramatic as instant death, they’re still very real. So real, in fact, that the American Horticultural Society has developed a kind of heat index that gardeners can use to determine whether a plant is well suited to the summer weather in their neck of the woods. Because (very generally speaking) many plants begin to suffer when the temperature hits 86°F, the AHS looked at how many days the temperature exceeds 86°F in various parts of the country and created 12 separate heat zones.

Care to take a guess how many days the temperature exceeds 86°F each year, on average, in the DC metropolitan area? Between 61 and 90, which puts us in Heat Zone 7.

By comparison, other parts of the East Coast that share our Plant Hardiness Zone (such as Long Island, NY and portions of the coast of Maine) experience only 15 to 30 days of 86°F-plus weather a year. Same range of minimum cold temperatures in winter, but significantly fewer days of high heat stress in summer. So it’s no wonder their mid-August gardens look much fresher and happier than ours.

An absolutely unblemished cutting garden outside Brunswick, Maine

Thankfully, all hope is not lost. Far from it. There are lots of plants that don’t just survive but really thrive in our climate. In fact, there are many more options than you probably imagine (and that you typically see in DC area gardens).

No worries, you’ll still get to complain about the weather. But by picking plants suitable for hardiness and heat zones 7, you’ll also have plenty of reason to smile as your landscape shrugs off the worst that our challenging winters – and summers – have to offer.


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