Inconvenient Frost, The Cold Side of Global Warming

The frost I feared last week (see below ) was a doozy all right; 25 degrees at 5AM on April 30th. Theoretically, that’s normal. Frost-free date for this area is supposed to be May 10th. What’s abnormal was the whole rest of April, which had very few frosty nights and many days with temperatures in the high 70’s to low 80’s.

That heat produced a premature explosion of new growth, tender young succulent stems, leaves and flowers defenseless against cell bursting ice.

Result? The magnolia of course got trashed – what was left of it. But the plum and apple blossoms were spared and to my everlasting surprise and delight, the Viburnum carlesii came through unscathed, every perfumed petal intact.

However. Carnage was visited upon: a large clump of trumpet lilies, wisteria almost in bud, the Miscanthus ‘giganteus’, which was already going great guns, and a beautiful Japanese maple, new last year, that has been my pride and joy.

It also made mush of the bleeding hearts,

Before frost, under the viburnum.

and heaven help us a peony. Just one, and not too badly, but still. A PEONY! Is nothing safe?

The answer, unfortunately is no. Most of the worry about global warming is focussed on droughts, floods and overhot summers, but there’s more to it than that. Unwanted warmth followed by VERY unwanted cold is going to be a fact of life from here on out. To deal with it:

* Plant new spring bloomers as though they were fruit trees: on a north slope, so heat comes late and frost drains away.

* When you remove winter mulch to avoid smothering fresh shoots, keep the mulch material nearby, so you can rake it back over them if/when frost threatens.

* Resist the temptation to prune the roses. You don’t want to encourage the new growth, and leaving the dead and weak stems in place helps keep frost-produced dieback above the wood you want to keep.

* be sure you have a supply of floating row cover aka spun-bonded crop-protector. It’s much lighter than bedsheets, far easier to use, and although it’s ungreenly made of plastic, it lasts practically forever if you take good care of it. Sources include Pinetree Garden Seeds and Johnny’s Selected Seeds
This doesn’t mean you can turn those sheets to rags; the row cover is only good down to about 28 degrees; if you fear even greater misery, use sheets. Either way, remember the purpose is mostly to trap ground heat; a hat that simply keeps frost from touching tops won’t help unless the frost is very light.

For more tips, see the advice posted last fall; a lot of it is useful at planting time.

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