Tower Garden Seeding Guide: How Many Seeds Should You Use?

March 26, 2021

📚 Part of the Living Towers Seeds & Seedlings Guide
Learn how to choose crops, start seeds successfully and grow healthy seedlings for your Tower Garden.

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Starting seeds for your Tower Garden? One of the most common questions is how many seeds should you put in each rockwool cube?

The answer depends on what you're growing. Large fruiting plants such as tomatoes need only one seed per cube, while herbs, spinach and baby greens are usually planted with several seeds together.

Use this Tower Garden seeding guide as a quick reference, then download our Tower Garden Seeding Cheat Sheet below so you can keep the seed counts handy when you're ready to plant.

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Find your crop or jump straight to the downloadable seeding cheat sheet.

Lettuce Herbs Leafy Greens Fruiting Crops Strawberries Seeding Cheat Sheet

How Many Lettuce Seeds Per Rockwool Cube?

Head Lettuce

1 seed per cube

Bibb, iceberg, butterhead and other head lettuces should generally be started with one seed per rockwool cube. One small seed can grow into a full head, so multiple plants aren't necessary.

Leaf Lettuce

1 seed in cooler weather; 2–3 seeds in summer

Loose-leaf lettuce grows best in cooler conditions. During summer, planting two or three seeds can give you more leaves to harvest during the shorter growing window before heat encourages bolting.

Spring Mix & Mesclun

6–8 seeds per cube

If you're growing a baby-green-style lettuce mix, you can plant up to about 12 seeds per cube for a fuller harvest.

For more lettuce-growing help, see our complete Tower Garden lettuce guide .

How Many Herb Seeds Per Rockwool Cube?

Chives

20+ seeds per cube

Chives naturally grow as a cluster, so you need considerably more seeds than you would for a large individual plant. We generally wouldn't use more than about 50 seeds in one cube.

Basil, Cilantro, Parsley, Dill & Other Herbs

6–8 seeds per cube

Several seeds in one cube create a fuller herb planting while still leaving enough room for the plants to develop.

How Many Leafy Green Seeds Per Rockwool Cube?

Kale, Chard, Collards & Mustard Greens

1–2 seeds per cube

These plants can become quite large, so one or two seedlings per cube is plenty. Chard in particular can become surprisingly large when grown in a Tower Garden.

Spinach

5–6 seeds per cube

Spinach can be more challenging to germinate consistently, so we use several seeds in each cube to improve the chances of getting a useful cluster.

Arugula

6–8 seeds per cube

Arugula grows quickly and works well when several seedlings are grown together in the same rockwool cube.

How Many Fruiting Crop Seeds Per Rockwool Cube?

Beans, Peas, Cucumbers & Melons

1–2 seeds per cube

One or two plants can share the same starting cube. If both grow, remember that each plant still needs enough light and space as it matures.

Squash, Tomatoes, Peppers, Eggplant & Okra

1 seed per cube

These crops become much larger plants, so one healthy seedling is all you need in each rockwool cube.

Should You Start Tower Garden Strawberries From Seed?

Strawberries can be grown from seed, but they're slow to establish and aren't usually our preferred way to start strawberries for a Tower Garden.

If your goal is to begin harvesting sooner, established strawberry plants or starts are the more practical choice.

See our guide to growing strawberries in a Tower Garden for more help.

Seeds Still Not Germinating?

Using the right number of seeds doesn't guarantee germination. Moisture, temperature and seed quality also matter. If your seeds aren't sprouting, see Seeds Not Germinating? 5 Common Reasons Why .

Download the Tower Garden Seeding Cheat Sheet

Want a quick reference while you're planting? Download our Tower Garden Seeding Cheat Sheet and keep it handy when you're starting your next batch of seedlings.

Download the Seeding Cheat Sheet