Winter Comes to Spring

April 11th, 2016

Just when we thought spring sprang, along came a couple of inches of snow this past Saturday along with near record-setting overnight low temperatures.

Just when our hyacinths and gardens thought it was spring, look what we got on Saturday.

I took the snow more as an insult – a little more than a harmless, quick-melting “onion snow” but not enough to cause any lasting plant damage.

The cold was more of a problem. Temperatures dipped down into the mid-20s overnight Saturday into Sunday, close to our official all-time record Harrisburg-area low of 26 degrees for April 10.

That posed a threat to fruit trees in particular. When the flower buds on those get far enough along, they become much more susceptible to cold damage than when the buds are still tight and dormant.

Cherry trees were in full bloom heading into the weekend, and apple and pear were showing colored tips. I’m afraid it got cold enough that at least some of the buds on home fruit trees got zapped.

Cold-killed flower buds translate into no fruits later.

The good news is that even if cold kills all of this year’s flowers and fruits, it won’t harm the trees themselves. We’ll get less or no fruit this year, but trees will go back to normal production for next year.

Bush fruits such as blueberries and raspberries are slightly more cold-hardy than some of our fruit trees (especially apricots), but these also can get whacked by freeze if it gets cold enough late enough. Mine looked like they came through the cold night fine.

How much damage you see will vary depending on your location, exactly where in the yard you planted (microclimate differences) and exactly what you planted (cold tolerance varies from species to species and even variety to variety within the same species.)

Check your buds to see how everything fared. If they’re wilted or browned or “mushy-looking,” that’s bad. If they’re looking firm, vibrant and pretty much in the same shape they were late last week before the cold and snow, you’re probably good. However, if the buds drop off in a few weeks instead of forming baby fruits, it could be it was just cold enough to abort the process without being blatantly obvious.

In any event, keep this little event in mind in case you have a lousy fruiting year.

You might also notice some browning around the leaf edges of fruit trees as well as perennials and ornamental trees and shrubs in the landscape. In my yard, some of the young hydrangea and rose leaves wilted from the overnight freeze.

Don’t worry about that. It might look alarming, but hardy plants like these will grow through leaf damage and sometimes even push out a second set of undamaged leaves. Leaf buds in general are cold-hardier than flower buds.

Things like Lenten rose, brunnera and ‘Ogon’ spirea — already in bloom — weathered the weekend in my yard with no sign of setback – flower or leaf.

Ditto for spring bulbs, such as daffodils, hyacinths, glory-of-the-snow, Siberian squill and the first few early tulips. These are used to cold spring weather and can slough off an April night in the 20s.

Here’s what tomato seedlings look like after a frosty night.

The biggest disaster from the weekend record-setting cold was with gardeners who jumped the gun and planted warm-weather vegetables and annual flowers.

Cold-tolerant crops such as cabbage, onions, broccoli, peas and lettuce and cold-tolerant flowers such as pansies and violas are equipped to handle even low-20s overnight temperatures, but the same isn’t true for summer veggies and flowers.

These include tomatoes, melons, cucumbers, peppers, beans and squash in the vegetable garden, and petunias, marigolds, vinca, celosia, coleus, begonias and zinnias in the flower garden.

That’s why most gardeners wait until the danger of frost has passed to plant these.

When’s that? It varies from year to year, but on average, our last killing frost date is April 20. That means that half of the years we’re done with frost by then, but half of the years we’re not.

Our all-time latest killing spring frost is May 11. That’s a safer milestone for most people, meaning it’ll take a record-setter to get our tomatoes and posies after then.

What I usually do is hold off planting the tender stuff until early May, then look at the 7-day forecasted lows.

When the overnight lows aren’t supposed to dip below 40, I plant – figuring that by the time we get to mid-May, we’ll be at the all-time record late frost date for Harrisburg.

It’s not unusual, though, for frosts to happen later than that to the north of Harrisburg and in outlying areas, which is why Halifaxers and Newporters often wait until close to Memorial Day to plant their tomatoes and petunias.

If you plant early and face a frost warning, your two options are to dig the tender plants back up and store them inside overnight, or drape floating row covers, sheets, plastic or similar light covering over them overnight.

Keep in mind that row covers only give you a few degrees of protection. When temperatures dip down into the low 20s, your tomatoes are likely to be history even inside a row cover.

Me filling a Wall-o-Water plant protector with water.

I’ve had much better luck protecting early-planted tomatoes with Wall-o-Waters, which are plastic protectors that have cylinders filled with water. Those reliably protect plants into the low 20s, and they allow me to plant a couple of tomatoes every April 1.

It used to be you couldn’t buy summer veggie plants and tender annuals this early. But in the rush to jump-start sales sooner, box stores in particular have been bringing in warm-weather veggies and annuals as early as the first week of April.

If you got tempted and now are looking at mush where your baby Big Boys were, your only recourse is to try again – preferably in late April or May.

As for the April snow, that isn’t terribly unusual around here, although most April snows tend to be light, short-lived dustings.

Our all-time record for most snow in April is April 11, 1894, when gardeners were treated to an “onion snow” of 13 inches.

As for the latest ever snow, we’ve had traces even into summer – including a tenth of an inch on July 9, 1930.

I guess you’d have to call that one a “tomato snow.”

I’m packing away my snow blower anyway. Here’s hoping I won’t have to drag it back out this July.