Friday, 13 April 2012

Vegetables that survive a polar climate

Here in Iceland, growing seasons are usually small. The spring is between May and August, sometimes it can snow even as late as early June, and frosts often begin by late August.

Last summer was unusually cold and dry. However, the weather remained mild until November, when suddently a severe frost began, and deep snow acumulated until February, when the weather warmed. This allowed many vegetables to survive in a good shape until that time. However, the tricky Icelandic winter brought many frosts/thaws since after. Nevertheless many vegetables managed to survive the hrash Icelandic winter!

Carrot family: extremely cold resistant vegetables
Carrots were completely unaffected by the polar winter! So tasty carrots! They enjoy the cold summer and do not seem to mind the extreme cold and snow. Another proof that the carrot family is well adapted to polar climate, are the native herbs Angelica, Lovage, Cumen and Sweet Cicely. Celery survived very well the first frosts, since then it suffered a bit, but most plants are still ok. Celery is quite cold hardy, especially Celeriac (the bulb forming variety). Another proof of cold hardiness comes from a Florence Fennel plant that survived the polar winter in our garden. Fennel is a warm loving vegetable, but still one plant survived and has now a nice side shot coming from its bulb. I think perennials like Skirret and Water Celery could be good investements as Icelandic perennial vegetables.

Onion family: very cold resistant vegetables
The onions from last year they are annuals, so I did not expect them to grow back again. However, the spring Onions were unaffected by the cold winter. If they are moved from indoors to outdoors they can suffer some minor damage but recover well. This might be because of their stored energy and thick leaves. I expect other species to be able to survive the winter and naturalize/ establish on a garden. Garlic, Multiplier onions (A. cepa agregatum), Walking onions (A. cepa proliferum), Welsh onions (A. fistulosum), Perennial leeks (A. ampeloprasum), Chives and Ramps (A. tricoccum or A. ursinum).

The Survivalists!
Many vegetables survived. Broccoli that did not flower last summer was well alive in February, but the following frosts killed most of the plants, but one or two still are still alive. Kohl Rabi was a crop that managed to survive several plants until now, better than the Broccoli. Brussels sprouts also surprised me; the plants were quite resistant to the cold, despite having a small size. All these crops seem to be cold hardy, but they need to be established there first. Rucula also survived but less. The cabbage family vegetables should be aclimatized before moving outdoors as they suffer cold damage quite dramatically, if not prepared. Some common herbs also survived: Lavender, Peppermint, Hyssop. The Thyme and Sage suffered heavily, and a bit of it survived. Perhaps they must be heavily mulched. Furthermore, there is a native species of Thyme here that is extremely adapted to the polar climate. More unaffected were the Lemon Balm and the Oregano.

The cold sensitive!
The Chicory survived the first frost in a good shape, I was excited about it, but the following frosts completely killed all plants. Beets and Swiss chard initially survived well the first frost, but did not stand a change to the rest of the frosts. However, they adapt well if transplanted outside in the cold spring and thrive during the cold summer. The Turnips, Radish Pak Choi and Mustard did not survive even the first frost. But they set seed before the winter. The same for the Calendula; these showed some signs of life after the first frost, but the rest of the winter killed them.

The cold hardy!
And likewise, Kale, a very cold hardy plant, is now beautiful. It seems to be unaffected, if the soil is protected by a mulch cover. S. Other unaffected vegetables  were the Rhubarb, Blueberries, Raspberries and the Lovage, some of them native to Iceland. There are also native Strawberries that stand the polar cold, but the cultivated varieties do not stand the cold. Some wild flowers demonstrated to completely stand unaffected the winter: Poppies, Ranunculus, Anemone, Tulips, Crocus, Muscari, Daffodils, Lupins, Astilbe, and even the Lilies. They all show a surge in growth just now, even if the weather is still cold. Carnations survived but suffered a little bit. There are herbs which stand the polar winter relatively well: Lady Mantle, Meadowsweet, Valerian and Angelica.

The surprise was the containers of tomatoes and eggplant. I had the dead plants standing outside, during the whole winter. As I brough the containers indoords, I was shocked to see some new seedlings from tomatoes and eggplants coming!

Warm loving crops
What about the warm loving vegetables? Obviously they do not survive the winter, but some of them can be cultivated during the polar summer. Squash grows quite well, if transplanted from a greenhouse, when it is already big. However, Cucumbers did not grow outside in Iceland (too cold). I haven't tried Pumpkins, but I heard people growing them with success in Alaska. I tried Bush Beans, but the warmth is just not enough; they also die when transplanted outside in cold spring, with frosts; Peas grow well; they are much more cold resistant and stand some frost and snow. They do not germinate if the ground is cold, but they stand very well hard frosts (even seedlings). I am currently trying Lentils outside; and the seedlings show the same kind of resistance. The plants also stand hard frosts (even in seedling stage) and adapt well to cold.

Perhaps less known perennial pea-family edibles could be attempted in Iceland, as the family obviously shows some cold hardiness. Lettuce obviously does not survive the polar winter, but the small plants do not mind a minor frost. They germinate well even with frosty weather.
Tomatoes seem impossible to grow. The plants stop growing if night temperatures are below 10ºC. They suffer leaf damage if temperatures are around 5ºC and are not adapted. But they grow excellent inside, because there is so much sunlight during polar summer. Potatoes can be sucessfully grown outdoors if started late, and having mulch protection. They are well adapted to cold conditions.

In summary - growing vegetables in a polar climate:
  • Carrot family: very cold hardy in Iceland
  • Onion family: very cold hardy in Iceland
  • Cabbage family: cold hardy in Iceland (except turnips, oriental types, radish, mustard)
  • Beet family: cold sensitive (do not survive polar winter)
  • Squash family: can be grown outdoors during polar summer (if transplanted big)
  • Bean family: cold-hardy members can be grown outdoors (not beans)
  • Nightshade family: excellent if indoors (potatoes can be grown outdoors)
  • Cereals: barley is grown outdoors (perhaps other crops can be grown too)

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