How to Grow Hydroponic Spinach

hydroponic spinach

Starting off on the Right Foot with the Right Equipment

Beginning your hydroponic spinach journey with the right equipment is the first step to growing hydroponic spinach. Check to see if there are any local hydroponics stores near you. They will have all the equipment and expert advice you may need at the start of your hydroponic journey.

You can also look online and read reviews for hydroponic systems. We have a variety of products reviewed on our site. The benefit of shopping online is you can compare prices from a variety of retailers. Some systems are all-inclusive, and others are void of lights. LED grow lights are important to all growing systems, so make sure to research and get everything you need before you get down with your seeds!

Start with Seeds Versus Seedlings

This gives the hydroponic gardener control over the type of seed used. Seed type is important, and as you can imagine, there are various brands of seeds to chose from, so how is one to choose which seed to start with?

Asking experienced gardeners tends to be a favorite way to discover hidden gems. We’ve written a great resource for finding the best hydroponic seeds. Burpee and Rare Seeds are other reliable seed companies as well. The options are endless when it comes to seeds.

Another reason to consider starting your hydroponic garden with seeds is that you can bypass any trauma the seedling plant may have incurred during its travel to your home. After carefully and thoughtfully considering your seeds, it is time to plant!

As seen in the video below, keeping your seeds in the refrigerator for a few weeks before sowing has many lifelong hydronic farmers swearing the plants produced are healthier. This process is called cold stratification and ensures seeds sprout properly. In hydroponic gardening, you want to mimic the natural habitat of the plant in nature as closely as possible and keeping seeds cold before planting does just that.

Planting hydroponics differs greatly from regular gardening. Since this type of gardening does not require soil, picking the hydroponic grow medium in which to plant the seeds requires care. To give your seeds a home, prepare plug trays with starter plugs such as Rapid Rooters, which are cubes of rockwool, coco coir, coco peat, and oasis plugs. Rockwool is nice because it easily permits oxygen and water to reach the seed, which works with NFT, drip, and deep-water culture systems.

Cornell University recommends an expanded polystyrene plug tray (pictured below) for baby spinach creation.

Once you have this step accomplished, you are ready to fill the plugs with a water solution with hydroponic nutrients. Cover them with water a fair amount as seen in the video above and let sit for an hour. Then, remove excess water and get ready to plant the seeds!

Time to Sow

You will want to sow about 4-6 seeds per hole which will almost guarantee a seedling as long as you keep your seeds moist. Plant each seed about ½ deep. Drying out of seeds leads to poor germination rates.

Also, consider the area in which you will germinate the seeds. It should be separate from other grow areas as it needs very stable and warm temperatures. The air needs to be moist and full of oxygen, with sufficient sunlight. If needed, use a heating mat to warm the seeds, but only if the grow room is in a cold area like a basement. The seeds will be kept in this warm, shaded area for up to two days.

Hydroponic Spinach: Cool-weather crop

The room where your hydroponic set should be kept in the daytime between 63-70 degrees as spinach is a cool-weather crop. At night, spinach grows optimally in the low 60s. Too warm of temperatures produces bitter spinach, causing it to ‘bolt’. High humidity is not recommended for hydroponic spinach.

Lighting for about 12 hours a day the entire time growing the spinach hydroponically is ideal, but during the bright and long months of summer supplemental light may not be needed. Shade may be needed if your spinach gets too much sunlight as it is a cool-weather crop.

Seedlings sprout within 3-4 days. Trays should be kept in a controlled, humid environment until this occurs.

The video below gives a detailed look at the sowing process in Oasis plugs, which are recommended for hydroponic spinach growing. Oasis plugs are made from water-absorbent foam and are also known as Floral Foam.

From seedling to transplant

The process of seedlings becoming strong is called propagation. Whenever the spinach looks hungry, giving it fertilizer is the solution. Maintain a pH around 5.6-6. You can reduce the feeding strength as the spinach matures, which wards off a bitter taste.

After about 20 days, the baby seedlings are strong enough to transplant. When the roots have extended out from the rockwool (or whatever your chosen medium), and the seedling is a few inches tall and has 3 leaves, then place the spinach seedlings into your hydroponic system of choice. This is the time to fertilize your hydroponic spinach with about ¼ strength. Spinach also likes calcium and magnesium as nutrient supplements.

Spinach fully matures in roughly 30-40 days. The great thing about the spinach plant is you can either harvest the whole plant at once or small amounts at a time. Harvesting just before full maturity can ensure a more tender and better tasting hydroponic spinach. Having a continuous supply of hydroponic spinach is one of the many benefits to growing this great green crop!


Why grow hydroponic spinach?

Spinach is a healthy, leafy dark green vegetable. Cook it sauteed in olive oil and garlic as a side dish, mix it in a smoothie, or eat it in a delicious salad. Spinach is rich in iron, vitamin K, vitamin A, vitamin C, folate, manganese, magnesium, and vitamin B2. Hydroponic spinach is spinach grown hydroponically (without soil).

A great benefit of growing spinach hydroponically is less risk of insect infestation and consistency in the crop yielded. Weeding and digging and other laborious gardening tasks are removed with hydroponic gardening. You can also control the environment the spinach is grown (ideally cool-weather) and avoid bitter spinach. The ability to have a continuous crop might be the best benefit of growing hydroponic spinach.

Why is my hydroponic spinach dying?

Likely due to spinach diseases such as damping off . According to Cornell University another reason is a water-borne pathogen called Pythium aphanadermatum that attacks the roots and causes poor crop quality and crop death. They recommend that if root disease occurs, the ponds and solution tanks should be drained, and the crop sacrificed. All equipment should be washed with a 2% bleach solution to prevent the proliferation of disease.

How long does it take to grow spinach hydroponically?

Hydroponic spinach typically grows in around 52 days, or 6 weeks, then it’s is ready to eat!

Help! What causes hydroponic spinach leaves to fade yellow?

This is usually a sign of nutrient deficiency in plants. Since spinach is sensitive to inadequate nitrogen, this means you need to add compost every 10-14 days. If you add aged compost to the planting beds a few times a year, nitrogen deficiency can be avoided.

How do you grow spinach in water?

That is the beauty of hydroponics! Growing spinach in water is called hydroponics. The plants get what they need from water, not soil. There is also something called aquaponics, which combines aquaculture and hydroponics into one system. Think fish meet water meet spinach living harmoniously until harvest time. How it works is the waste produced from the fish carries the nitrates plants need to grow.

Does hydroponic spinach regrow after cutting?

You can either cut and harvest the whole plant or small amounts at a time. When you correctly harvest the chance of the hydroponic spinach regrowing is high. Cut the spinach back to about 2 inches of the ground, being cautious around the crown of the plant so as not to disturb this area. In about 4 weeks, you can expect regrowth for a second harvest of hydroponic spinach.

How do I grow to have a continuous supply of hydroponic spinach?

Every two weeks, sow seeds and repeat the process and you will have a continuous supply of fresh spinach at your fingertips!

Have you tried growing hydroponic spinach? Leave us a comment below and leave any tips for budding growers!

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