Growing Arugula Hydroponically: A Complete Tower Garden Guide

Starting Arugula From Seed

Arugula is different from larger crops such as tomatoes, peppers or cabbage where we normally want a single plant growing from each rockwool cube.

For arugula, we plant 6–8 seeds per rockwool cube. This gives you a fuller cluster of greens from each Tower Garden planting port.

Keep the rockwool evenly moist while the seeds germinate, but don't leave the cubes sitting in excess water. Once the seedlings emerge, provide plenty of light to encourage healthy growth.

Living Towers offers arugula both as seed and as a hydroponic-ready seedling, so you can start your own or skip the germination stage.

For more information about starting hydroponic seeds, see our How Many Seeds Should I Plant? article and Seeds & Seedlings Guide.

Where Should Arugula Go in a Tower Garden?

Arugula is much easier to fit into a mixed Tower than large crops such as broccoli, cabbage or squash.

It doesn't need a cage, trellis or special pollination access, so you have plenty of flexibility when choosing a planting port.

As always, consider the plants growing around it. A small leafy green can eventually become shaded if it's planted directly beneath a large tomato, squash or other vigorous crop.

How Much Light Does Arugula Need?

Arugula needs good light for healthy, productive growth.

Outdoors, place your Tower where the plants receive plenty of useful sunlight. In very warm climates, conditions will be different from a cool northern garden, so watch the plant rather than assuming every growing recommendation has to be identical in every climate.

Indoors, provide approximately 14–16 hours of grow light per day, followed by complete darkness overnight.

With Tower Garden grow lights, keep the lights approximately 6–8 inches from the tops of the plants.

For more information, see our Tower Garden Light Guide.

What Temperature Does Arugula Like?

Arugula is commonly considered a cool-weather leafy green, and cooler conditions can certainly be favorable for it.

But climate recommendations aren't always as absolute as they sound.

At Living Towers in South Florida, we grow arugula successfully year-round. That includes conditions considerably warmer than the temperatures you'll often see recommended in generic arugula growing guides.

As temperatures and seasons change, pay attention to the actual plant. Growth rate, leaf quality, water use and how quickly a plant begins flowering can all tell you more than the calendar alone.

Water and Nutrients for Hydroponic Arugula

Arugula doesn't require a special nutrient formula. It can grow in the same Tower Garden alongside lettuce, herbs and fruiting crops.

For an established Tower Garden, our standard Mineral Blend rate is 20 mL of Mineral Blend A and 20 mL of Mineral Blend B per gallon of water.

For young seedlings, use approximately half strength — 10 mL of A and 10 mL of B per gallon.

During very hot weather, we may reduce nutrient strength further depending on growing conditions.

Keep the Tower's pH approximately 5.5–6.5 and check the reservoir regularly.

See our Tower Garden Nutrients Guide and Tower Garden Water Guide for more detail.

Can You Grow Arugula Indoors Hydroponically?

Yes. Arugula is a good candidate for an indoor hydroponic garden because it doesn't require pollination, doesn't need support and doesn't take up the amount of space required by many fruiting crops.

Provide enough grow light and allow complete darkness overnight. As neighboring plants mature, make sure they aren't blocking the arugula from the lights.

Because you can harvest leaves repeatedly, arugula can also make good use of an indoor planting port without waiting months for one large harvest.

Can You Grow Arugula Year-Round in Florida?

Yes — we do.

We grow arugula year-round at Living Towers in South Florida. That's worth mentioning because you'll frequently see arugula described only as a fall, winter or spring crop.

That doesn't mean temperature becomes irrelevant. Hot-weather growing affects the entire Tower, including reservoir temperature, water use and nutrient strength. But it does mean you shouldn't automatically assume arugula has to disappear from your Tower when summer arrives.

Common Problems When Growing Arugula Hydroponically

My arugula is growing tall instead of producing lots of leaves

Check the amount of light the plant is receiving. Plants that aren't receiving adequate light can stretch toward the light source. Also check whether the plant is beginning to move toward flowering.

The leaves are yellowing

Don't automatically add more nutrients. Check pH, nutrient strength, water quality, roots, light, temperature and the overall condition of the plant first.

The leaves have holes

Inspect both sides of the leaves for pests. Because arugula is grown for its foliage, even a relatively small amount of chewing damage can become noticeable quickly.

My arugula tastes stronger than usual

Arugula naturally has a peppery flavor, and its flavor can change as the plant matures and growing conditions change. If you prefer milder leaves, harvest them while they're younger and more tender.

Common Arugula Pests and Diseases

One advantage of checking a Tower regularly is that pest problems can often be caught before they become major infestations.

Look over arugula leaves when you harvest. Pay particular attention to the undersides of leaves and tender new growth.

Aphids, whiteflies and leaf-chewing pests can all affect leafy crops. If you notice damage, identify what is causing it before deciding how to treat the plant.

For help identifying and managing common problems, see our Tower Garden Pests & Diseases Guide.

How Do You Harvest Hydroponic Arugula?

You don't need to pull the entire plant when you want some arugula.

Once the plants are established and the leaves have reached a useful size, harvest the larger outside leaves while leaving the younger center growth in place.

This allows the plant to continue producing new leaves for additional harvests.

Regular harvesting also helps keep the plant manageable and gives you fresh leaves when they're at the size and flavor you prefer.

What Happens When Arugula Starts Flowering?

Eventually an arugula plant may begin sending up a flower stalk rather than concentrating primarily on leaf production.

If your goal is a continued supply of tender leaves, this is usually a good time to consider replacing the plant with a younger one.

Because arugula is relatively easy to start from seed, succession planting can help keep younger plants coming along while older ones reach the end of their most productive leafy stage.

Is Arugula a Good Crop for a Tower Garden?

Yes. Arugula checks a lot of boxes for Tower Garden growers.

It doesn't require pollination or support, you can grow several plants from one rockwool cube, and you can harvest leaves repeatedly rather than dedicating a planting port to one eventual harvest.

It's also easy to mix with other crops, so you don't need to fill an entire Tower with arugula to make it worthwhile.

For us in South Florida, the ability to keep growing it throughout the year makes it even more useful.

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