How to grow spinach from seeds to harvest

Francis Ndolo at his vegetable farm in Thika, Kiambu County. There are two types of spinach, savoy (or curly) and flat leaf. [James Wanzala, Standard]

Are you thinking of starting a vegetable garden? Then try spinach. Spinach is a cool weather crop adaptable to most regions. Spinach does best when growing in moist, nitrogen-rich soil.

To start, select a planting site with full sun or partial sun, and well-drained soil. Mix the soil with compost manure two weeks before planting.

Choose the right variety based on your needs. There are two types of spinach, savoy (or curly) and flat leaf.

Flat leaf is commonly frozen and canned because it grows more rapidly and is easier to clean.

Savoy cultivars taste and look better, but their curly leaves make cleaning difficult as they tend to trap sand and dirt.

They also keep longer and contain less oxalic acid than flat leaf spinach. Select the disease-resistant varieties to minimise incidences of rust and viruses.

Soils

Spinach prefers a neutral to alkaline soil with a pH 7.0 or above. In acidic soil, lime the soil before planting.

Spinach is also a heavy feeder and therefore requires complete fertilisation at planting followed by side dressing after two weeks.

Apply the fertiliser 4 inches from the base of the plants to avoid burning the roots. Maintain a consistent soil moisture.

Irrigate deeply and regularly especially during dry periods. Water stress will encourage plants to start forming seeds.

Although seeds can be started in a nursery, it is not recommended, as seedlings are difficult to transplant. 

Plant spinach seeds an inch apart in rows 14-18 inches apart and cover the seeds with a 1/2 inch of soil preferably on raised beds.

Keep the soil moist and after the seeds germinate thin them to stand 3-5 inches apart.

Make sure the plants are adequately spaced or you will end up with lots of small leaves.

This is achieved by thinning (gently pulling out the unwanted plants, leaving the healthiest in place). Most gardeners like to do this in several passes to determine the strongest plants to save. 

Thin spinach to 12 inches (30cm) apart when seedlings are 3 inches (7cm). Thin to the strongest seedlings.

Remove weak seedlings by cutting them off at the soil level with scissors. Overcrowding leads to stunted growth and encourages plants to start forming seeds.

Care

Keep the garden free of weeds to avoid competition for light, water and nutrients.

Cut weeds at soil level rather than digging them out; because spinach has shallow feeder roots which can be injured by digging. Apply mulch to suppress weeds.

Spinach will bolt in temperatures greater than 24 degrees centigrade. In warm weather, protect the crop by covering with shade nets.

Spinach can be attacked by aphids, flea beetles, leaf miners, slugs and spider mites. Usually a high-pressure water spray will knock them off.

You can also pinch the heavily infested leaves by looking for eggs on the underside of the leaves. Floating row covers can exclude leaf miner flies from the planting bed. 

Spray flea beetles and spider mites with spinosad. Keep slugs and snails away from spinach by sprinkling a barrier of diatomaceous earth around plants.

Spinach blight virus which is spread by aphids, causes yellow leaves and stunted plants.

Downy mildew, appears as yellow spots on leaf surfaces and mold on the undersides, occurs during very wet weather.

Reduce the spread of disease spores by not working around wet plants. Avoid both of these diseases by planting resistant cultivars.

Harvest your crop at six to eight weeks by carefully cutting the outside leaves. This will extend the plants’ productivity.