In praise of cold frames

The mild weather has had me snooping around in the cold frames this week. I opened the cold frame which contains hundreds of pots of seed sown back in November. It’s always fascinating to see which seeds germinate in cold weather. This time I see various alliums, crucifers, umbellifers, crocuses (Crocus imperati) , fritillaries (Fritillaria tuntasia) and tulips (Tulipa cretica). This is exciting.

Another use for cold frames is the protection of marginally hardy plants or the protection of precocious blooms. For instance, I put a florists’ cyclamen in the cold frame sometime before Christmas, and it really seems to be taking to those conditions. Some Primula acaulis bought as flowering plants have settled right in – I expect them to bloom for weeks at least (unless I forget to open the frames on a sunny day and they get cooked). A rooted piece of Daphne odora is opening flowers now ,too.

Those of us who live in USDA zone 7 and who have read the British gardening literature experience a severe frustration with respect to winter blooming plants. Zone 7 is just a bit too cold to support a British-style winter garden. In some years it works; it works often enough to keep some of us interested in trying. But sooner or later the winter comes which closes the garden firmly for weeks on end. Almost all plants of which I’m aware with winter-blooming potential close down shop. Skunk cabbage is an exception, and isn’t it strange that almost everyone who knows and enjoys this plant is content to enjoy it in the wild: I have never seen it in a garden (there are seedlings here).

But let’s get back to the cold frames. We envy those British growers who tell us about a crocus season which lasts from sometime in September until sometime in March. That simply isn’t possible in the open garden here. But it is possible in a cold frame. And it’s not only possible for crocuses, it’s possible for daffodils and snowdrops, too. There has been a daffodil of one sort or another blooming in my protected cold frame since sometime in September. There have been snowdrops since mid November. Although most of the crocuses were moved to an unprotected bed two years ago, I did leave some corms of the Crocus sieberi cultivar ‘Firefly’ in the protected frame, and they are in bloom today. When grown in cold frames, all of these plants tend to have an extended bloom time – they last much longer (and in better condition) than they would in the open garden. A clump of Galanthus elwesii (the one I call my Christmas snowdrop) dug in bloom from the garden on December 18, 2009 is still in full bloom a month later!

Little rewards like this make the cold frames well worth the bit of bother they entail.