Hard Frosts Don’t Harm Bulbs

There has been an early spring in many areas, with the result that bulbous plants are popping up extra early. Some of them may just be showing leaves, but the earliest ones – snowdrops, crocuses, winter aconites, etc. – may well be in bloom. Of course, in some climates, even tulip season has begun. It all depends on where you live.

However, anywhere you can grow hardy bulbs outdoors, there is always a risk of a late frost, even snow. And those risks are increased when spring is earlier than usual. What should you do if a hard frost is predicted and your poor bulbs are already up and growing?

What to Do?

The answer is… nothing. Hardy bulbs (tulips, hyacinths, narcissus, crocuses, etc.) all hail from cold climates, mostly mountainous areas, where irregular spring temperatures are the norm. They’ve had thousands of years of getting used to unseasonable weather. Most will sail right through late frost and even snow without any damage whatsoever, even when they are in full bloom. In fact, frosty nights actually help extend their bloom. I’d seen snowdrops last nearly a month on a regime of cold nights and days barely above freezing, yet only a week or so when the spring was exceptionally warm.

The earliest bloomers, from snowdrops right through muscaris, are the most frost resistant: you often seen them covered in frost crystals at dawn and in perfect shape come noon. Or see them get covered in snow and still blooming away when the snow melts, even days later. In Val-d’Or, Quebec, where the ground remains frozen well into May and nightly frosts are common even in June, tulips routinely get frosted, yet show no damage when they thaw out again.

Heavy Snow

Even heavy snow has little effect on most bulbs: they seem designed by Mother Nature to handle it. Most narcissus, for example, are already somewhat bent over. When snow accumulates, they simply bend down further under its weight then rise back up when it melts. I’d be more concerned by heavy snow on double hyacinths and taller double-flowering tulips, the flowers of which have a tendency to snap off when they get too weighty. It their case, it might be wise to insert a few stakes into the garden, higher than the plants, then cover them with a tarp or old blanket just before the storm, thus creating a sort of snow-proof tent.

But of course, that’s only if heavy snow is predicted and only on a few exceptionally weighty flowers. In most cases, you don’t need to do anything to protect bulbs when frosts or snow are likely to occur.