Home Vegetable Gardening Growing Hydroponic Spinach: A Comprehensive Guide to Harvesting Sweet, Bitter-Free Spinach

Growing Hydroponic Spinach: A Comprehensive Guide to Harvesting Sweet, Bitter-Free Spinach

by Gregory
4 minutes read

Growing Hydroponic Spinach: A Step-by-Step Guide to Harvesting Sweet, Bitter-Free Spinach


Spinach is a leafy green vegetable that is packed with nutrients. It is a popular choice for salads, smoothies, and other healthy dishes. However, growing spinach can be challenging, especially if you live in an area with a short growing season. Hydroponics is a method of growing plants without soil, using nutrient-rich water. It is a great way to grow spinach year-round, even in areas with limited space.

Tips for Growing Hydroponic Spinach

Here are some tips to help you grow delicious, bitter-free hydroponic spinach:

1. Use Fresh Seed

Spinach seeds can take anywhere from 7 to 21 days to sprout. It is important to use fresh seed to ensure good germination rates.

2. Sow Seeds Properly

Sow 4-5 seeds per hole in a heavy sowing medium. This will help to ensure that you have at least one strong, healthy seedling per cell or cube.

3. Cold Stratify Seeds

Place spinach seeds in the refrigerator for 1-3 weeks prior to sowing. This will help to improve germination rates and produce healthier plants.

4. Keep Seeds Moist

Poor germination rates and unthrifty plants can occur if sowed seeds are allowed to dry out during the germination process. Keep seeds moist but not soggy.

5. Avoid Seed Heating Mats

Spinach is a cool-weather crop that germinates best between 40 and 75 degrees F. Higher temperatures can result in poor germination rates.

6. Stagger Plantings

To have a continuous supply of fresh spinach to harvest, sow seeds every 2 weeks.

7. Time the Transition to Hydroponics

Ideally, wait to place spinach seedlings into the hydroponic system until the roots have extended out from the germination medium. The seedlings should be 2-3 inches tall and have 3-4 true leaves.

8. Control Temperature

As a cool-weather crop, spinach grows optimally with a daytime temperature between 65 and 70 degrees F. and night temperatures in the 60 to 65-degree F. range. Warmer temperatures can cause spinach to bolt, which increases bitterness.

9. Avoid Overfertilizing

Begin feeding spinach seedlings when they are transplanted into the hydroponic system. Use a weaker solution of hydroponic nutrients to start and gradually increase the strength. Leaf tip burn indicates that nitrogen levels are too high.

10. Reduce Light Exposure

For optimal growth, maintain 12 hours of light per day when growing spinach using hydroponics. Light in the blue color spectrum promotes leaf growth and is desirable for hydroponic spinach production.

11. Reduce Fertilizer Strength and Temperature Prior to Harvest

The trick to producing sweeter-tasting spinach is reducing the ambient temperature by a few degrees and decreasing the strength of hydroponic nutrients as spinach plants near maturity.

Troubleshooting Bitter Spinach

If your hydroponic spinach is bitter, there are a few things you can do:

  • Check the temperature. Spinach that is grown in temperatures that are too warm can become bitter.
  • Check the nutrient levels. Too much nitrogen can also cause bitterness.
  • Reduce the amount of light that the spinach is exposed to. Too much light can also make spinach bitter.


Growing hydroponic spinach can be a rewarding experience. By following these tips, you can grow delicious, bitter-free spinach all year round.

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