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

March 26, 2021

📚 Part of the Living Towers Seeds & Seedlings Guide
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Starting seeds for your Tower Garden? One of the most common questions we hear is how many seeds should you put in each rockwool cube?

And the answer is... it depends! 🌱

One tomato seed can grow into a huge plant, while chives prefer a crowd. Some leafy greens are happy growing in little groups, and others need plenty of elbow room.

We've put together this handy Tower Garden seeding guide so you don't have to guess. And there's a downloadable cheat sheet at the bottom to keep nearby when you're planting your next batch.

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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 📚 Continue Learning

🌱 How Many Seeds Per Rockwool Cube?

Here's the quick version before we get into the details:

Large fruiting plants: Usually 1 seed per cube.
Head lettuce: 1 seed per cube.
Most herbs: 6–8 seeds per cube.
Chives: 20 or more seeds per cube.
Baby greens: Several seeds per cube for a fuller harvest.

These are our general planting recommendations. Keep reading for crop-specific counts!

🥬 How Many Lettuce Seeds Per Rockwool Cube?

Not all lettuce grows the same way. Some varieties form beautiful individual heads, while others are perfect for harvesting a handful of leaves whenever you need them.

🥬 Head Lettuce

1 seed per cube

Bibb, iceberg, butterhead and other head lettuces generally need just one seed per rockwool cube.

One tiny seed can grow into a full head of lettuce, so there's no need to squeeze several plants into the same cube.

🌱 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 the heat encourages bolting.

🥗 Spring Mix & Mesclun

6–8 seeds per cube

Growing a baby-green-style lettuce mix? You can plant up to about 12 seeds per cube for a fuller harvest.

These are great for picking young, tender leaves for salads.

Want more lettuce-growing tips? Check out our complete Tower Garden lettuce growing guide.

🌿 How Many Herb Seeds Per Rockwool Cube?

Herbs are a little different from larger vegetables. Many grow beautifully in clusters, which means you can plant several seeds together for a fuller, bushier harvest.

🌱 Chives

20+ seeds per cube

Chives naturally grow as a cluster, so don't be shy with the seeds!

We generally wouldn't use more than about 50 seeds in one cube. You want a nice bunch of chives, not a miniature jungle.

🌿 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.

It's a great way to grow a generous supply of fresh herbs for cooking.

Love growing fresh herbs? Our Growing Herbs in a Tower Garden guide has more tips for keeping your herb garden productive.

🥗 How Many Leafy Green Seeds Per Rockwool Cube?

Leafy greens are some of our favorite crops to grow in a Tower Garden. They're productive, versatile and perfect for picking fresh whenever you need them.

But don't treat them all the same when it comes to planting seeds!

🥬 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.

Swiss chard in particular can become surprisingly enormous in a Tower Garden. Give it some room to show off!

🌱 Spinach

5–6 seeds per cube

Spinach can be a little stubborn when it comes to germination. Planting several seeds in each cube improves your chances of getting a useful cluster of seedlings.

🥗 Arugula

6–8 seeds per cube

Arugula grows quickly and works well when several seedlings share the same rockwool cube.

Perfect if you love that peppery kick in your salads!

🍅 How Many Fruiting Crop Seeds Per Rockwool Cube?

Now we're talking about the big growers! Tomatoes, cucumbers, squash and peppers can produce impressive harvests, but they also need room for their roots, leaves and fruit.

With these crops, more seeds definitely doesn't mean more success.

🥒 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.

For larger varieties, you may prefer to keep just the strongest seedling.

🍅 Squash, Tomatoes, Peppers, Eggplant & Okra

1 seed per cube

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

That little tomato seed might not look like much today, but give it a few months! 🍅

🌱 What If More Than One Seed Sprouts?

If you've planted extra seeds for insurance and more than one germinates, you may need to thin the seedlings, especially for larger fruiting crops.

It's better to start with one strong plant than several competing for the same space.

🍓 Should You Start Tower Garden Strawberries From Seed?

Technically, yes, you can grow strawberries from seed. But would we recommend it for most Tower Garden growers? Probably not!

Strawberries grown from seed can be slow to establish, so if you're hoping to enjoy fresh strawberries sooner rather than later, established strawberry plants or starts are usually the more practical choice.

For more advice, check out our guide to growing strawberries in a Tower Garden.

🌱 Seeds Still Not Germinating?

Using the right number of seeds is only part of the equation. Moisture, temperature, seed quality and growing conditions all play a role.

If your seeds are refusing to make an appearance, take a look at Seeds Not Germinating? 5 Common Reasons Why.

📥 Download the Tower Garden Seeding Cheat Sheet

Want to avoid searching for seed counts every time you start a new batch?

Download our handy Tower Garden Seeding Cheat Sheet and keep it nearby when you're planting. It's a quick reference for how many seeds to put in each rockwool cube.

Download the Seeding Cheat Sheet →