Starting and Caring for Spinach Seedlings
Spinach loves the cool temperatures of spring and fall, and it can even be grown in winter down to temperatures as low as 20ºF (-6.6ºC) once the plants are past the seedling stage. You can start spinach seeds in flats indoors or in a greenhouse, or, you can sow spinach seeds directly into prepared garden soil.
Spinach seeds germinate in a temperature range between 40º to 75ºF (4.4º to 23.9ºC), and the higher the temperature, the faster the seeds sprout. Start your spinach crop indoors about four weeks before the last frost date for your area when growing spinach seedlings for transplanting in the spring.
When starting spinach indoors, plant the seeds into a tray or pot at least 4 inches (10cm) deep, because spinach seedlings develop a deep taproot and you want to give the roots plenty of room to grow.
When sowing seeds in a tray or directly into the garden, plant the seeds about ½ inch deep (1.3cm) deep and 3 to 6 inches (7.6 to 15cm) apart, and then press the soil firmly over the seeds and water them right away. Keep the soil continuously moist and germination will usually occur in 5 to 10 days.
Transplanting Spinach Seedlings
Spinach is a heavy-feeder, which means it likes an especially nitrogen-rich soil. Enrich the soil by adding:
- Decomposed manure
- Blood meal, fish meal, or cottonseed meal
Mix the fertilizer into the soil before planting, and then plant your seeds or transplant your spinach seedlings into the amended soil.
Once the seedlings have germinated and are about 3 to 4 inches (7 to 10cm) tall, fertilize them once a week with dilute fish emulsion or another nitrogen fertilizer, and lush, dark green leaves will develop and quickly grow.
Succession Planting for a Longer Harvest
Spinach plants mature in as little as 35 days after germination, and most varieties will bolt and produce a flower stalk after about 60 days of growing, making the leaves bitter and tough. If you want a continuous crop of spinach, start a fresh batch of seedling every two or three weeks until temperatures get too hot, which is a daytime high of about 75ºF (24ºC).