Beetroot, Sugar Beet and Chard (Beta vulgaris)

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Domesticated in the ancient Middle East primarily for their greens, beets were grown by the ancient Egyptians, Greeks and Romans, and were later cultivated for their roots as well. Today, several different varieties can be found in gardens and farms, grown for their edible taproots (commonly referred to as beetroots) and leaves (called beet greens). Other cultivars of the same species include the sugar beet as well as the leaf vegetable known as chard or spinach beet.

Raw beetroot contain 16-20% sugar and is a rich source of folate and a moderate source of manganese. It is a major source of sugar in many temperate areas, widely used in cooking. About one third of all sugar production in the world is derived from this plant. It has excellent potential as a biomass crop, where the plant residue can also be used for fuel.

Growing recommendations

Beets are a cool are a cool-season, biennial vegetable crop that will grow well in a variety of soils and climates with mild temperatures during flowering. They however prefer deep, friable, and well-drained soils with a pH of 6.0-6.8 and that are abundant in organic matter. Beets will grow best in full sun in an open location, but can tolerate some shade. Most varieties are ready to harvest about two months after planting depending on the variety, climate and planting date.

Beets are usually direct seeded a month before last spring frost but can be started in a greenhouse and transplanted thereafter. Varieties that are grown in fall should be planted at least two months before the first expected fall frost. Germination will take 5-10 days at temperatures ranging from 12-25° C. Plants for seed production should then be thinned to 10 cm for garden beets, 25 cm for sugar beets, and 30 cm for chards.

While beets can be propagated via cuttings, plants grown using this method will not be suitable for seed production as there will be no bulb regrowth.

Common diseases and pests

• Bacterial diseases: Bacterial blight (Pseudomonas syringae pv. aptata), scab (Streptomyces scabies).
• Viral diseases: Beet curly top disease (beet curly top virus (BCTV), beet severe curly top virus (BSCTV), beet mild curly top virus (BMCTV)), beet western yellows virus (Beet Western Yellows Virus (BWYV)).
• Fungal diseases: Cercospora leaf spot (Cercospora beticola), damping off (Rhizoctonia solani, Phoma betae, Pythium ultimum, Aphanomyces cochlioides), downy mildew (Peronospora farinosa), fusarium yellows and root rot (Fusarium oxysporum f. sp. spinaciae, Fusarium oxysporum f. sp. betae), powdery mildew (Erysiphe betae).
• Insect pests: Darkling beetle (Rove beetle) (Blapstinus spp., Staphylinid spp.), leafminers (Lyriomyza spp.).
• Nematodes: Beet cyst nematode (Heterodera schachtii), root knot nematode (Meloidogyne spp.).

Pollination, crossing, and isolation

Beets’ very small flowers are produced in dense spike-like, basally interrupted inflorescences. They are hermaphrodite (urn-shaped, green or tinged reddish, consisting of five tepals, five stamens, and two or three stigmas) and pollinated by wind, making them strongly outbreeders. Their pollen is light and can be carried over long distances, which will require adequate isolation techniques to ensure the purity of the varieties that are grown. If sufficient space is not available and spatial isolation not possible, several flower stalks can be isolated and bagged together before the flowers open in order to prevent cross-pollination. A minimum of six plants should be included in each paper bag. The wind will help to move pollen from the male to the female flowers. In the absence of adequate wind, vigorously shaking the plants each day will produce a similar effect and ensure that they are pollinated. The bag should be left in place until all the heads have matured and the seeds ready to be harvested.

General seed saving guidelines (harvesting and processing)

As with other biennial root crops, beets will require two seasons to produce seeds. Beets will indeed not flower until their roots are mature and have been subjected to at least a month of cold temperatures (vernalization). In cold areas where beets are planted in the spring, using the seed-to-root-to-seed method might be more adequate. The mature roots are carefully dug up before the first frost, sorted and selected based on specific criteria (size, shape, color). Any off-type plants must be rogued out. The tops are cut (leaving 5 cm of green) and the tips of the roots are trimmed (to about 15 cm). The roots are then placed in a bucket filled with damp sand or sawdust, covered with a layer of dried leaves, and stored in a humid location (90-95 %) at 0-5° C for 4-6 months. In the following spring, the best roots are replanted for seed production.

In mild winter climates, beets planted in the later summer are left in the ground over winter and will bolt (produce a flower stalk) next spring, following a seed-to-seed method. The formation of seeds will usually start six to ten weeks after the emergence of the flower stalk. The seeds are encapsulated inside clusters – a multiple-seeded fruit resulting from the fused dry corky bracts of two or more flowers that occur at the same node – each one typically containing two to five seeds. As the flowering habit is indeterminate, flowering and subsequent seed maturation will continue until harvest or frost. As beet seeds mature gradually, the number of seeds reaching full maturity at the time of harvest will typically not exceed 75 % of the total seed crop.

The first seeds to set are often of a higher quality and have a high germination rate. These will readily shatter and will have to be harvested as soon as they are mature in order to minimize losses. As more seed mature, subsequent harvests can be conducted. The entire seed stalk can also be cut and dried further when it has been determined that the majority of the seed clusters has reached maturity (exhibiting a light brown color). Once fully dried, they can be placed inside a bag and threshed by beating them with a stick or trampling over it with the help of your feet. The seeds are then winnowed to remove any remaining chaff and pieces of stems and leaves.

Note that cool, wet weather can often occur during the late season, making it even more important to closely monitor the seed maturity and not harvest too early or too late. Early harvest may result in a percentage of seed that is not fully mature. Harvesting seed past the optimum time period may result in reduced yield and seed quality due to seed shattering and an increased incidence of seed borne diseases.

Beet and chard seeds are lenticular, 2-3 mm, with a red-brown, shiny seed coat. They will remain viable for an average of six years when stored under optimum conditions.