Grow and Save Swiss Chard Seeds

How to Grow Swiss Chard

Swiss chard (Beta vulgaris) is a green with a unique taste. Swiss chard and beets are the same species, and they require a period of overwintering in order to set seeds. Plants can be lightly harvested in the first year for food, and then set to overwinter and produce seeds the following year.

Time of Planting

Plant seeds outdoors as soon as soil can be worked in the spring.

Spacing Requirements

Direct sow seeds 2 inches apart and later thin to 6-12 inches apart. Sow seeds ½ inch deep.

Time to Germination

5-10 days

Special Considerations

When growing for seed, increase spacing to 19 inches between plants in rows 36 inches apart, or to 24 inches on center in the second year. Staking plants is recommended.

Swiss chard is the same species as beets. When growing for seed, these two plants can cross-pollinate and therefore must be isolated from one another in their second year.

Common Pests and Diseases

Downy mildew can be a problem for Swiss chard when grown close together as baby greens. Birds also enjoy the leaves, but protecting new seedlings under row covers can deter them.

When and How to Harvest for Food

Swiss chard can be continually harvested throughout the season. Harvest the outer leaves at the base of the stalk, leaving four to five inner leaves to continue growing.

Swiss chard can also be harvested in closer plantings as baby greens, cutting the leaves about 3 inches above the soil and returning every week or so. Allow plants to re-grow to 5-6 inches before harvesting again.

Eating

Swiss chard can be steamed, used in soups, or as an addition to salads and sandwiches.

Storing

Leaves can be kept in the fridge in airtight containers for a few days.

How to Save Swiss Chard Seeds

This crop is a biennial, meaning that it will not set seed until the second year of growth. At seed maturity, plants of this species take up a fair amount of garden real estate.

A benefit to growing Swiss chard for seed is that you can lightly harvest the plants in their first season for food, and then let them overwinter and harvest the seeds the next year.

Life Cycle

Biennial

Recommended Isolation Distance

Separate flowering varieties of Beta vulgaris by 800 feet to 1 mile.

Remember: isolation is important during flowering, but not until then. Flowering does not happen until the second year of growth, after at least 10 weeks of vernalization. If there are no other flowering beets or Swiss chard within 800 feet to 1 mile, you have achieved the recommended isolation distance. 

Recommended Population Sizes

To ensure viable seeds, save seeds from at least 5 plants. When maintaining a variety over many generations, save seeds from 20-50 plants. If you’re saving seeds for genetic preservation of a rare variety, save seeds from 80 plants or more.

Vernalization

Swiss chard is a biennial crop that requires vernalization to trigger its reproductive phase. In order to flower, plants must be subjected to temperatures below 40 degrees Fahrenheit for at least 10 weeks. Overwinter the Swiss chard in your garden if your garden meets this requirement and maintains a minimum temperature of 18 degrees Fahrenheit or above. Mulch or row cover can help protect the temperatures.

If overwintering in the garden, sowing should be timed so that the crop will be slightly smaller than full size by winter because young plants are hardier to cold than mature plants. If your garden is too cold for in-ground vernalization, harvest and store Swiss chard when the soil is relatively dry, before the first hard frost.

Remove soil by brushing, but do not wash. Trim leaves to just above the crown by making 2-3 diagonal cuts upwards from the base of the leaf stems. Store in any ventilated container lined with wood shavings or sand. Remove any diseased plants before storage. Optimal storage is near 35 degrees Fahrenheit and 75% relative humidity. 

In the spring as soon as the soil can be worked, plants should be thinned or replanted with proper spacing for seed production: 18 inches between plants in rows 36 inches apart to accommodate the large flowering and fruiting branches that will develop. Staking is recommended.

Assessing Seed Maturity

Seeds at the base of the flower stalks ripen first, and seed maturation continues up the stalks. Seeds change from green to a tannish-brown color as they mature.

Harvesting

Once seeds start ripening, there will almost always be a mixture of mature and immature seeds on plants. Harvesting when approximately two-thirds of the seeds are brown is recommended.

Depending on the scale of seed collection, individual seedstalks can be cut or entire plants can be pulled from the garden and moved to a place where they can continue drying. Depending on the percentage of ripe seeds at harvest, 7 to 14 days should be a sufficient drying period.

Cleaning and Processing

The seedstalks can be threshed using one of several methods. Small lots and cut branches can be processed by running a gloved hand along the length of the stalk with a container placed underneath to catch dislodged seeds; stalks should be discarded once they are stripped of seeds.

Larger lots and whole plants can be placed in large tubs or on tarps and treaded upon. Threshed seedstalks should be discarded, and the seed lot should then be screened and winnowed.

Storage and Viability

When stored under cool, dry conditions, beet seeds can be expected to remain viable for 5 years.

Learn more about storing seeds.