Everything You Need to Know About Hydroponic Spinach

Spinach from our R&D Vertical Greenhouse.

Hydroponic farming is one of the most exciting trends in agriculture today. While there are a great number of plants that can be grown using this method, leafy greens are a favorite. One crop that does amazingly well in a hydroponic environment is spinach. This delicious and healthy plant grows wonderfully in a hydroponic greenhouse for year-round fresh greens!

Growing Spinach Hydroponically

Growing spinach hydroponically is easier than some hydroponically grown produce and more challenging than others. There are a few requirements that you must meet to grow healthy hydroponic spinach plants. As with all plants, there are certain things you’ll need to know before you plant your first hydroponic spinach seeds.

You first need to know that spinach is vulnerable to Pythium contamination, which is common in some hydroponic systems. This can lead to root rot and destroy your entire crop before it reaches maturity. Because Pythium is a common contaminant found almost everywhere, it’s nearly impossible to completely keep it out of your greenhouse. Instead, focus on routinely cleaning any surface that might come in contact with your plants or nutrient solution. Ensure adequate aeration, and never use surface water sources for your spinach crops.

Optimal Growing Conditions for Spinach Hydroponics

Next, you must understand the best-growing conditions for spinach to set your hydroponic microclimate controls appropriately. In traditional growing methods, you’d have to worry about when to plant spinach, which is in season only in the spring. When grown hydroponically, spinach can be harvested year-round, offering fantastic health benefits every season.

What Is the Best Temperature for Hydroponic Spinach?

Spinach is a cold weather crop, so avoid temperatures above 75° F. The optimal temperature for daytime is 65-70°.

How Much Light Is Needed for Hydroponic Spinach? 

As for light, spinach does best with a 12 hours-on and 12 hours-off cycle. Direct sunlight is best, but fluorescent, high-pressure sodium, or HID lighting will work too. If your setup allows you to choose light color bands, blue light is ideal as it is best for leaf production.

Hydroponic Spinach Nutrient Requirements

Calcium and magnesium are the primary nutrients you’ll need for your spinach plants. Avoid too much nitrogen as it can cause leaf tip burn. You’ll want to start with a light nutrient mix, then raise it gradually after a few weeks until you get to full strength. Before harvest, lower your nutrient strength again to prevent leaves from becoming bitter.

Harvesting Hydroponic Spinach

Before your spinach harvest, you’ll want to make a few changes to your hydroponic system’s settings to produce sweeter spinach leaves. Reduce the temperature a few degrees and decrease the nutrients you’re feeding your plants just before they hit maturity.

When ready to harvest, use sanitized scissors or shears and cut the outer leaves off first. You may then choose to leave the smaller inner leaves on the plant so they can continue to grow or go ahead and harvest them if they’re big enough for your purposes. 

How Long Does It Take to Grow Spinach Hydroponics? 

The specific variety of spinach you choose and the type of hydroponic system you use can make a big difference in growing times. That said, most types of spinach take about 40-50 days from seed to harvest. Hydroponic spinach in systems that promote fast growth may be ready to harvest in as few as 35 days.

How to Store Hydroponic Spinach

Once your spinach has been harvested, you can store it the same way as any other type of spinach. In general, hydroponic spinach you’ve grown yourself will likely last much longer than traditionally grown spinach from the grocery store, but there are still some tricks you might want to use to keep it fresher longer. 

The best way to store spinach to keep it fresh is to place it in a resealable container layered with paper towels to absorb any moisture. Change the paper towels as they become damp, as moisture could cause your delicate leaves to decay. 

Keep your spinach away from ethylene-producing produce like bananas and apples unless it’s in an airtight container. Ethylene exposure can cause your spinach to age faster and go bad prematurely.

Health Benefits of Hydroponic Spinach 

Spinach is an incredibly healthy leafy green, great for salads or cooking various recipes. Many people choose spinach for its energy-restorative properties and its high iron content. Spinach also contains elevated levels of vitamins K, A, C, and B12, folate (vital for pregnancy), and minerals such as manganese and magnesium. It’s a wonderful food for bone and blood health and is incredibly versatile in its uses.

We wrote an article on 10 hydroponic health benefits if you'd like to know more.

What Spinach is Best for Hydroponics? 

While nearly any type of spinach can be adapted to grow well in your hydroponic growing system, some make the process easier than others. Here are our picks for the best hydroponic spinach varieties:

• Bloomsdale is an heirloom spinach variety with curly dark green leaves that are easy to grow.

• Monnopa is a low-acid variety with some of the sweetest leaves of any spinach variety.

• New Zealand spinach produces delicious triangle-shaped leaves repeatedly as long as you don’t over-harvest.

• Noble Giant Spinach is one of the most common spinach varieties, producing glossy dark green leaves.

Why Is My Hydroponic Spinach Dying? 

Few things are more frustrating than putting all your effort into growing delicious spinach plants only to have them die before they reach maturity. There are a few reasons this could happen, and fortunately, they can be corrected once you figure out the problem. 

Most commonly, the problem may be in the root system. If your plants aren’t getting enough oxygen at the root level, this can cause root rot and a wilting spinach plant. 

Another common spinach problem is when spinach produces seeds before the leaves ever have the chance to reach maturity. This is typically caused by either too much light or too high temperatures. 

If your problems begin even earlier and your spinach seed fails to germinate, you might not be providing enough moisture. Raise the level of moisture fed into your germination setup, and you’ll achieve far better results.

What Causes Hydroponic Spinach Leaves to Fade Yellow? 

The most common problem with hydroponic spinach plants is when leaves begin to fade to a sickly yellow color. This typically means you have a nitrogen deficiency in your hydroponic nutrient solution. Adding more nitrogen should solve the problem and return your hydroponic spinach plants to health.

Frequently Asked Questions 

Does Spinach Do Well in Hydroponics?

When given the proper nutrients, lighting, and temperature settings, spinach can grow very well in a hydroponic environment.

Does Hydroponic Spinach Regrow After Cutting?

If you’re careful to only harvest about a third of each spinach plant, you can continue to regrow spinach leaves repeatedly from the same plant. In this case, new leaves will regrow every few days.

What Is the Best Spinach to Grow Hydroponically?

Nearly any spinach variety can be adapted to a hydroponic system. That said, some types of spinach are easier to grow than others. A few of the best spinach seed options for hydroponic growers are Bloomsdale, Monnopa, New Zealand, and Noble Giant spinach. 

Is Spinach Easy to Grow in Hydroponics?

Spinach is fairly easy to grow in a hydroponic environment, though not as much so as many other varieties of leafy greens. 

Is Hydroponic Spinach Healthy?

Yes. Hydroponic spinach contains vitamins K, A, C, and B12, folate, manganese, and magnesium.

Does Hydroponic Spinach Need to Be Washed?

Generally, hydroponic spinach is not susceptible to contamination from pesticides and such. That said, washing your spinach leaves before consuming them is still a good idea, just in case they’ve come into contact with anything you wouldn’t want to ingest.