Biennial vegetables in flower are among the most interesting things for a gardener to see. Apart from being quite lovely (parsnip, leek and celery flowers could easily be garden ornamentals), they are a necessary stage of growth that is rarely seen. Most commercial seeds of cabbage, beet, turnip, celery and other biennials are grown further south, mostly overseas. The reason that you don’t see these plants in bloom here is that some care is usually needed to keep them alive through the winter.
No doubt, many readers have seen onions and cabbage-family plants survive a mild winter. If you’re a learned gardener, you might leave your leeks and parsnips in the garden over winter on purpose—they’re soft, sweet treats in the spring and they often survive temperatures down to -20OC. But most biennials, including carrots, beets, turnips, and celery need protection.
If you’d like to save your own seeds of biennial vegetables, it’s quite easy. Since your neighbours probably won’t be doing it, there is virtually no chance of cross-pollination with other varieties (the exception is carrot which has a common wild form throughout Canada). Or if you’re just interested in seeing a celery flower, it’s worth a little space in the garden.
To save the seed of biennials, you have to help the vegetables survive the winter. Hardy plants like leeks, parsnips and salsify will often overwinter in the garden, especially if they are covered with a thick cover of snow, leaves or straw. The mulch and snow insulate the dormant roots, protecting them from rapid changes in temperature.
More tender plants, such as carrot, beet, turnip, cabbage and its relatives, should be kept cold and humid for the duration of the winter. Crops can be stored in slightly moist sand or sawdust, or just loosely in a box or bag if cold and humid enough. They will keep until spring this way. Be careful not to bruise or scratch the skins of the root crops, since this increases their chance of rotting.
An old-fashioned earthen cold cellar is ideal, since it stays consistently cold but never gets too frigid to kill the plant roots. Unfortunately, I don’t have one of these. My house’s concrete cold cellar gets cold enough in the winter, but it warms up in March and it is too dry. My sand dries out, roots sprout too early, and my attempts to humidify the roots cause them to rot because the cellar is too warm.
So I make my own little earthen cold cellar every year. The frost in my area usually goes about two or three feet into the ground, so in the fall I dig a hole in the garden three feet deep and maybe two feet wide. Into the hole goes an armload of leaves, then some of my nicest cabbages, eight or ten turnips, and a plastic bag of carrots and beets. Another armload of leaves. Then I gently lay some short pieces of scrap wood on top, and fill the hole with soil. I usually mound it up with all the soil that I dug out.
In mid to late April, it’s time to replant the biennials. The scrap wood protects them from my shovel as I dig them out, and I always find that most of the plants are bedraggled, but still alive. I pot them up and put them in a shady spot until they sprout new green leaves, and plant them in the garden. By this time, it is early May. The plants withstand frost, and burst forth with astonishing vigour from the stored energy in their mature roots.
Two-year-old beet plants are strange to see. Dig beets before a hard freeze. You can remove fibrous roots, and carefully brush off most of the soil, but do not wash. Cut off the leaves 1/2″ above the crown, since they will dry or rot in storage. Store roots in a cool, humid place. In late spring, replant the beets in the garden with the crowns at the surface. New roots grow from the bottom and sides of the beet, and new leaves grow at the crown. By mid-summer, several rangy branches will have grown from the crown with tiny flowers along their lengths. Seeds appear in late summer, clustered along the sides of the branches.
Carefully dig cabbages before a hard freeze, keeping as much of the roots as possible. Store at least six heads in a cold, humid place over winter. Replant in late spring. Cabbages produce tall flower stalks with dozens of yellow flowers which turn into seed pods. If the head is wrapped tightly in a ball, you may have to cut an ‘X’ in the top of the head to let the flower stalks emerge.
Dig, clean, store and replant carrots the same way as beets. However, the common weed Queen Anne’s Lace is actually the original wild carrot. Your carrots will produce the same flower, and unfortunately can cross-pollinate with their wild ancestor if they bloom at the same time.
Celery may sometimes survive a very mild winter in the garden. It is best to dig several plants carefully, pack them in a box or bag of slightly moist sawdust or sand, and store in a cold humid place. Replant in late spring. Second-year celery grows three or four feet tall, and is festooned with lacy white flowers, which produce thousands of tiny seeds.
In a mild winter kohlrabi may survive in the garden, but it is best to store them if possible. Dig before a hard freeze, keeping as much root as possible. Trim leaves above the crown. Store good roots in a cold, humid place. Replant in late spring. Kohlrabi is really a form of cabbage and has identical flowers; it will cross with cabbage and its other relatives.
Leeks survive the winter easily in most regions, especially with a little mulch. Eat the blanched stem in early spring for a tasty treat! In their second year, each leek has a wonderful spherical flower which could easily qualify as an ornamental specimen. The flower produces hundreds of seed pods.
Parsnips are delightful when left in the garden over winter. The freezing and thawing softens and sweetens the roots, but they can no longer be stored well. Flower stalks can grow five feet tall, blossoming with large yellow flowers.
This root crop is interesting and worth trying, although it is not the easiest for beginning gardeners. The seedlings look like grass, so diligent weeders may inadvertently destroy their crop soon after sowing. Roots survive the winter in the garden in many regions, and lovely purple flowers appear in midsummer. The common wild salsify, with yellow flowers, is a different species and does not cross-pollinate with the purple-flowered kind.
Dig, store and replant turnips the same way as kohlrabi. Tall stalks bear yellow flowers in early summer, which turn into seed pods. At least ten roots should be overwintered, since five or six plants are needed for proper pollination.
Complete information on vegetable seed saving is available in Seeds of Diversity’s publication How to Save Your Own Vegetable Seeds, $8 from Seeds of Diversity, Box 36 Stn Q, Toronto ON M4T 2L7. For more information, see www.seeds.ca