Starting a Spinach Crop from Seed

Spinach seeds sprout easily, as long as you know how to care for them by keeping them in the correct temperature range during germination. You can start spinach seeds in flats indoors or in a greenhouse or cold frame, or, you can sow them directly in the garden. However, it is important to start spinach during the cool weather of spring or fall, otherwise the plants tend to bolt prematurely.


Starting Spinach Seeds Indoors or in the Ground

You can begin germination of spinach seeds indoors about four weeks before the final frost in your area, or, start them in the fall when temperatures are starting to cool down.

Do not start spinach seeds during the hot months of summer, because the plants quickly bolt when temperatures are over 75ºF (24ºC), producing a tall flower stalk, setting seed, and developing an unpleasant flavor.

Spinach seeds germinate best in a temperature range between 40º to 75ºF (4.4º to 23.9ºC), however, they come up faster at the higher end of this range.

Plant the seeds about ½ inch (1.3cm) deep in a flat filled with potting mix or in garden soil. Space the seeds about 2 to 3 inches (5 to 8cm) apart in all directions, if you are starting them in a flat and plan to transplant the seedlings. When planting in the ground, space rows approximately 12 inches (30cm) apart.

Best Conditions for Growing Spinach

Besides planting your spinach crop at the correct time of year, the most important points for growing this vegetable are:

  • Spinach seed is viable for 2-3 years. After that, germination rates quickly decline. Start with fresh seed.
  • Spinach prefers a slightly more alkaline soil than many other vegetables. Plant spinach in fertile, well-drained soil with a pH of 6.5 to 7.5.
  • Spinach grows fastest in full-sun, but as long as the plants receive at least six hours of direct light, they can tolerate some shade during the day.
  • Water spinach daily, keeping the soil moist at all times. Mulch helps prevent evaporation.
  • Spinach plants mature quickly with most varieties ready to pick in 35 to 55 days. Harvest individual leaves from the outside of the plant when small, or wait and cut the entire plant at full-maturity as indicated on the seed package.

Saving Seeds from Spinach Plants

Spinach is dioecious, having separate male and female plants. Male plants pollinate female plants with the help of wind, which distributes the yellow pollen to flowers on female plants.

Because it is wind pollinated, spinach plants can cross-pollinate over large distances. Nonetheless, if some of your plants go to seed, you can try collecting and planting seeds from female plants. However, the plants may not be exactly the same as the parent variety.