Growing seed for harvest 4: Carrots and brassicas

Organic NZ Magazine: January/February 2006
Author: Annie Wilson and Colin Walker

In the final of our series Annie Wilson and Colin Walker look at growing carrots and brassicas for seed.

The Koanga Institute was established to develop a national network of growers to support the seed bank started by Kay Baxter and the team at Koanga Gardens and ensure the survival of traditional food varieties. By growing heritage seeds you can help.

The humble carrot (Daucus Carota var. sativa) belongs to the Umbelliferae family or Apiaceae family, and is biennial. The perfect flowers (having both male and female parts) are pollinated by insects, often the smaller ones like the hover fly, which are attracted to the small flowers. They will cross pollinate with Queen Anne’s Lace, a prolific, wild relative, and any other carrot variety, so for seed saving grow only one carrot type at a time.

You can sow seed directly into deep loamy soil in Dec–January, and thin seedlings for space as they grow. In Zone 1 (from Kaikoura south) seed should be sown earlier in October–November.

Carrot seed takes a long time to germinate, so some people put a little radish seed in with it to mark the row ahead of the carrots appearing.

The plants grow through the winter months. In Zone 1 they should be dug up at the beginning of winter and the best carrots selected. Look for good colour and shape and trim the leaves to about 25cm and store in sawdust, sand, or leaves.

In the other zones they can be left in the ground to overwinter, but it is a good idea to dig down around the roots and check for desirable characteristics before selecting. They will then bolt the following summer, and seeds will become visible in the large umbel, turning brown when ripe. Care should be taken to
collect the seeds before they shatter, rubbing the umbels over a small gap mesh. This will clean some of the beard off the seed also. The seeds are very light-weight.

For saving seed in the short term, 60 plants should be sufficient, but for long term, at least 200 desirable plants should be saved for seed production. This ensures the genetic diversity of the stock.

Store seed in a cool, dry place. It will maintain a high rate of germination for three years, but then will drop off dramatically.

The Koanga Institute has a yellow, very disease resistant variety called Yellow Austrian Lobbericher, a huge, orange carrot called Wanganui, and the White Belgium carrot, particularly suited to warmer climates. Brassicas The Brassicaceae family was formerly known as the Cruciferae family and has a large membership of 350 genera.

In addition to the usual suspects – cabbage, cauliflower, brussel sprouts, broccoli and kale – members include mustard, cress, rocket, radish, horseradish, swede, turnip, Chinese cabbage, kohlrabi, and collard greens.

Their relation is easy to see in their flowers, which are all very similar, having four petals in a cross shape, hence the old name of Crucifera.

The Brassicas are the most difficult crop for the home gardener to successfully save seed from because of the large numbers of plants required to keep the genetic diversity stable.

Sixty plants for the short term, and 200 plus for the long term are needed, so a large growing area is required.

Additionally all members within each of the species can cross with one another, so a distance of at least 800m is needed between crops.

Try to select healthy plants that have obviously performed well in your particular region. Don’t keep seed from plants that have suffered insect damage or are small, with pale foliage.

Insects and weather won’t affect the genes of the plant, but will affect the number and quality of the seed. In Zone 1 cabbage and cauliflower should be germinated in January–February and grown through the winter. They will go to flower in November and seed can be harvested in the summer months. They prefer a cold period of dormancy, and will then begin to grow with increased vigour in the spring. For this reason the South Island really has the best conditions for brassica seed production. Some suggest marking a cross with a knife on the head of the cabbage after dormancy, to help the seed head push through.

Over the years, Koanga Gardens have perfected growing brassicas in northern areas where plants don’t have a dormant period. For example, broccoli is germinated in July; the plants then flower in November and the seeds are harvested in the summer.

Cabbage and cauliflower take longer and so go into the ground in late March, harvesting seed the following summer.

The Koanga seed collection has four different cabbage varieties available currently, Lachinato kale, Red Russian kale (a highly nutritious green), the very rare Borecole, and Ruruhau, which is an old Dalmatian mustard-green, and many weird and wonderful varieties of broccoli.

This concludes our seed saving series.

For more information on seed saving techniques, there are some invaluable books listed below. All are published in America.
* Seed to Seed by Suzanne Ashworth
* Saving Seeds by Marc Rogers
* Seeds of Change by Kenny Ausubel (This book is out of print, but is the most inspirational reading for anyone interested in heritage crops. I found three copies easily on the internet.)