How to Grow Cucumbers Hydroponically

By: Chris | Last Updated: January 18, 2021

Whether you think a cucumber should be eaten in a salad, dipped in delicious artichoke dip, or sliced and placed on your eyelids, learning how to grow cucumbers hydroponically would be of great benefit to your health and your wealth.

Cucumbers are mostly water (over 90%) and because of this they offer a plethora of health benefits along with a satisfying crunch. 

For obvious reasons, they are great at hydrating your skin, and they aid in losing weight and regulating your blood sugar when eaten regularly. The cucurbitacin found in cucumbers has been known to fight cancer cells, and the large dose of Vitamin K keeps bones healthy.

Often added with mint to water for a refreshing, calorie-free drink, cucumbers are also known to reduce puffiness and hydrate when placed on your eyes. The benefits seem endless, and they are certainly easy to fit into your diet and your life.

Hydroponic Cucumber Varieties

There are many varieties of cucumbers that grow well hydroponically, and it all comes down to personal taste. Several bush varieties, developed for container gardening, work exceptionally well in hydroponic systems. 

Varieties like Spacemaster and Salad Bush Hybrid will bear a lot of fruit, and their smaller plant size makes them ideal for hydroponic gardening. 

Apple cucumbers, lemon cucumbers, or Lebanese cucumbers are more interesting cultivars that are also fun to experiment with. They will offer a different taste sensation than more traditional bush varieties. 

How to Grow Cucumbers Hydroponically

The following tips will help you get situated as you try your hand at cucumber growing:

How to Grow Hydroponic Cucumber

Growing a plant made mostly of water IN water is a fun concept. From the taste of a cucumber slice, to its benefits in flavoring water and reducing puffiness, this is the perfect plant to grow hydroponically. 

Although vine plants are not the easiest to grow, the payoff is big for these crispy cukes. Once you get the hang of it, you will wonder why you didn’t start sooner.

Why hydroponics? Cucumbers need a LOT of nutrients, and when grown in water it is much easier to regulate the amount and timing of the nutrients fed to them. 

Additionally, the control of light cycles in indoor gardening helps maximize the yield of fruit bearing plants like cucumbers.

The viney nature of cucumbers means that they will need to be constantly trained to grow in the right direction. With a hydroponic setup, it is much easier than in a traditional outdoor garden to use a trellis or twine system.

Growing Hydroponic Cucumbers
You don’t need massive systems like this to grow hydro cucumbers. A DWC or Dutch bucket works great!

Cucumbers favor a Dutch bucket system, but can also be grown simply in a five gallon bucket, depending on your harvest needs and the space available for your indoor garden. 

There are only a few things you need to set yourself up for hydronic happiness and success:

Germinating Cucumber Seeds

You have a few options when it comes to germinating cucumber seeds. They can be sown directly into the growing substrate in a dutch bucket or DWC system. Also, they can be started in seed starter plugs on a heated germination mat. Finally, you can use the paper towel germination method on a heated germination mat.

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Regardless of the method you choose, cucumber seeds will germinate best with high humidity and high temperature and should start peeking their little green heads out after 3 to 10 days.

If sown directly in substrate or starter plugs, place seeds ½” to 1” deep. 

Growing from Cuttings

Cucumbers, like many plants, can be grown from cuttings. To do so, using a sterilized knife or sharp scissors, cut the outer 5 to 6 inches of a healthy vine. To be successful, the cutting needs to include two sets of leaves, and be cut from the donor plant just above a growth knot. 

A straight cut works best. After cutting, remove the two leaves closest to the cut, dip the cut end in rooting hormone and place it in a grow plug or directly into a hydroponic system. Cloning rings are useful for stabilizing cuttings while waiting for them to develop transplant-worthy root systems.

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Transplanting and Training Cucumbers

When seeds are ready to transplant, these viney plants will work well in a Dutch bucket or deep water culture system. If using a Dutch bucket system, buckets need to be spaced 15-36” apart depending on the variety of cucumber you’re growing. 

Training Hydroponic Cucumbers
Simple vertical twine systems help train and maintain hydroponic cucumbers

Plan on being very busy with your cucumbers. They grow prolifically but also need a lot of training. (You thought training your dog was hard!) 

Setting up a system to tame the vines with trellises is your best bet, but you will need to be hands-on often to help the vines grow in the right direction. You can use a twine system or trellis to train the cucumber vines, and keep them from getting out of control.

Temperature & Lighting

Make sure to keep the grow area warm, between 70-80 degrees Fahrenheit during the day. Dropping the temperature about ten degrees “at night” to simulate the growing season will offer you a better overall harvest. 

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Speaking of light, cucumbers need 12-14 hours of light a day, followed by 10-12 hours of darkness. This day/light cycle simulates the conditions a plant would thrive in if it were outdoors. 

Note: Cucumbers may require as much as 14-18 hours of artificial light. This will depend on the brightness of your grow lights. Adjust light timers and light distance from the plants based on how the plant is reacting.

Pollinating Hydroponic Cucumbers

Since you have taken the process of growing indoors, you have lost the ability for the bees to naturally pollinate your cucumbers. 

Female Cucumber Flower
Yep…That’s a female cucumber flower.

You will need to help Mother Nature in this task. Easily distinguishable, female flowers have a small cucumber at the base, while male flowers do not. 

Using a cotton swab or small brush, brush around the inside of the male flowers and then brush the inside of the female flowers. 

For optimal fruit production, repeat this process daily. 

It’s not extremely time consuming, and it’s well worth the extra work when you start seeing beautifully developed cucumbers emerge.

Harvesting Hydroponic Cucumbers

Cucumbers offer a rolling harvest, since they begin growing at different times and grow at different rates. Depending on how many vines you started with, odds are you can harvest a cucumber or two on any given day once the plant reaches maturity (50-70 days). 

When to harvest will depend on the variety of cucumber you’re growing. Most bush variety cucumbers are ready to harvest with the fruit is a healthy dark green color and measured 6 to 8 inches long. If you wait too long, the fruits will begin to develop a bitter taste. When it comes to cucumbers, early harvests result in sweeter fruits.

To harvest a cucumber, snip the cucumber with sharp shears or scissors taking care to leave around 1 inch of vine attached to the base of the cucumber. Also be careful not to pull the vine or dislodge it from the trellis. 

Some varieties of cucumbers are prickly, and you may want to use gloves as you harvest them.

Take a Break, You Earned it!

After all your hard work training your vines and planting and harvesting cucumbers, you will definitely need a spa day. 

Lucky for you, cucumbers offer just what you need to rehydrate your system, give you a healthful lunch, and reduce puffiness!

FAQ

Can cucumbers be grown hydroponically?

Yes, being over 90% water, cucumbers will thrive in a hydroponic growing environment. Their heavy reliance on nutrients and water makes them an ideal candidate for hydroponic culture.

How much light do hydroponic cucumbers need?

12-14 hours. If grown indoors with grow lights, cucumbers will need at least 12-14 hours of direct light from a high quality light source such as a full-spectrum LED or HID grow light.

What hydroponic systems works best for hydroponic cucumbers?

Dutch buckets or Deep Water Culture. Because of the size and weight of the plants, cucumbers are best suited to grow in Dutch (bato) bucket or DWC systems.

These systems are easy to integrate with trellises and other support structures that help support the mass of a growing cucumber plant.

What are the best cucumber varieties for hydroponics?

Bush varieties like Spacemaster 80 and Salad Bush Hybrid are well suited for hydroponic gardening. These varieties were developed with container gardening in mind.

Both produce wonderful fruit, while staying at a relatively manageable size.

What is the best temperature for hydroponic cucumbers?

65-75 degrees Fahrenheit. Seeds may germinate better at temperatures between 70-80 degrees Fahrenheit. This can be achieved by placing the seed tray on a heating pad designed for seed germination.

Mature plants will produce best with warmer temperatures during daylight hours, and slightly cooler temperatures at night.

When should the cucumber fruit be picked?

When the fruit is a healthy dark green in color, and has a length of 6-9 inches. Check the variety of cucumber you’re growing to find it’s optimal length at harvest.

Most bush varieties are ready for harvest when they reach a size of 6-8” in length.

Chris Cook started Happy Hydro Farm to share his passion for hydroponic gardening! Growing your own food is incredibly rewarding both physically and mentally. His mantra - "Take excellent care of your plants, and your plants will take excellent care of you."