Carrot

Botanical name : Daucus carota

Common name : Carrot

Summary Information

Challenging for seed saving

Lifecycle: Biennial

Pollination: Insect pollinated

Mating system: Perfect flowers in umbels

Suggested spacing: Mature carrots should be transplanted to 60cm spacings

Seed specific requirements: Vernalisation required

Isolation distance: 250 m

Population size: 20 or more plants

Seed maturity: Seeds in flower heads turn brown. The outer florets of the umbel cup and turn inwards.

Processing method: dry process

Expected seed viability: 4 years

Growing for seed

Carrots need to go through vernalisation in order to initiate flowering. Temperatures under 10 C are needed for this. In Australia there are few locations that get too cold for carrots to remain in the ground over winter so it is usually easiest to keep carrots in the garden for seed.

Carrots are somewhat prone to inbreeding depression and should be allowed to flower together in larger populations if possible.

When growing carrots for seed it is important to ensure they aren’t cross-pollinated by wild carrots or ornamental varieties such as Queen Anne’s Lace, including the chocolate and purple forms enjoyed by many flower growers. Isolation distances of at least 250 metres are required.

Selection

Carrots being grown out for seed can be harvested in mid-winter, their tops cut back and then replanted at the larger spacing required for seed production. This is the ideal time to select against cracking, forking, and splitting. Colour and form should also be considered when selecting those carrots to grow on to seed. The internal colour can be checked by cutting a few centimetres from the bottom of the carrot. This cut of tip can also be checked for flavour.

Rejects from the gene pool because of splits, forking and cracks. [photo: BVSS/LW]
Cutting the bottom off seed carrots to check core colour before adding to the gene pool. [photo: BVSS/LW]
Checking core colours on one source of Red-Cored Chantenay seed. [photo: BVSS/LW]
This selection of ‘Red-cored Chantenay’ were all grown from one seed source. [photo: BVSS/LW]
Only the carrot on the right meets the shape selection criteria for Red-Cored Chantenay. [photo: BVSS/LW]
Rejects from the gene pool at the front. [photo: BVSS/LW]

Harvest

Carrot flowers reach seed maturity in a continuous fashion over many weeks. The central flowerhead will mature first, followed by the smaller side shoots. The first matured seed will be the biggest and strongest seed so growers may choose to stop harvesting seed after the initial lot of side shoots are collected. As carrots need to be grown in sufficient populations for genetic stability enough seed may be achieved by harvesting modest quantities from many plants.

Seed heads are mature enough to be harvested for seed when the seeds have turned brown. The outer florets of the flowerheads bending inwards is a good indication that the head is ready to harvest.

Carrot flowerhead with seed mature enough to harvest. [photo: BVSS/LW]
Carrot flowerhead ready for seed harvest. [photo: BVSS/LW]
Carrot flowers at different stages of maturity on the one plant. [photo: BVSS/LW]

Processing

Carrot seed can be dislodged from the flowerheads by either rubbing them between gloved hands or rubbing the head over the mesh of a sieve. When they are rubbed on a sieve paying attention to just dislodging the seeds without dislodging portions of stalk can make the rest of the cleaning process easier.

Seed can be sieved and winnowed to remove unwanted frass.

Contributors

Liz Worth, Nellie Pryle