Beetroots are a biennial plant, which means that they only produce seed in their second year. This can make seed saving a bit trickier as you need to keep the beetroot alive through the winter months so it can produce seed the next summer.
Plants from the beetroot family will cross pollinate easily so only allow one variety to go to seed at any one time if you want to keep the strain pure.
Digging up the beetroot and storing it in a safe place protects it from the winter cold and makes saving seeds simpler. Dig up the plants you have chosen for seed in the autumn after their tops have begun to yellow and fall over. Dig around the root to loosen the soil; then gently pull the entire plant out of the ground.
Fill a large bucket with slightly moistened sand. Cut the leafy tops off and then bury the beetroots in the sand so they aren’t touching each other. Place the bucket in a protected area outside, such as on a veranda, until spring. Keep the roots lightly moist and protect them from freezing.
Replant the beetroots in spring at the same depth they were the previous year, and space them 10cm apart. Water as needed to keep the soil moist until they produce flowers in mid-summer.
If you live in a warm region that rarely has freezing temperatures in winter, you can leave the beetroots in the ground instead of digging them out. Cover them with a 10 cm layer of straw to help protect them until spring.
Allow the flowers to wither and die off. Seeds at the base of the flower stalks ripen first, and seed maturation continues up the stalks. The seeds will change from green to a tannish-brown colour as they mature.
Harvest when approximately two-thirds of the seeds are brown. Pull the beetroot up from the garden and move to a place where they can continue drying for 7 to 14 days.
Rub the seed heads between your thumb and forefinger while holding each seed head over a bowl. The seed will break free from the stalk and fall into the bowl. Pick out any extra plant matter from the seeds.
Place the seeds in an envelope or jar and seal closed the container. Label the container with the variety and year harvested. Store the jar in a cool, dark place until you are ready to plant. Beetroot seeds remain viable for up to three years after harvesting.