Skip to Content

How to Use Seed Starting Plugs

Getting ready to start a garden is such an exciting time. Deciding what to grow, gathering tools, and picking out seeds are all such fun parts of getting a garden going for the year.

Even though it’s a lot of fun, starting a garden from seed is also a lot of work! Tools that save time and make your life easier are one way to keep the work feeling like fun.

That’s what’s so great about seed starting plugs. Using plugs makes starting plants from seed simple and easy giving you more time to browse those seed catalogs.

If you’re thinking about using starter plugs, this guide is for you. I’ll go over everything you need to know about seed starting plugs including what they are, how to use them, and how to care for seedlings as they grow.

A pile of seed starting plugs.

What Are Seed Starting Plugs?

Before we get into how to use seed starting plugs let’s talk about what they are.

Plugs are compressed cubes or pellets that are designed for starting seeds and encouraging root growth from cuttings. You can use them to start plants from seed or to foster root growth in cuttings taken from other plants.

Most are individually wrapped and sold in trays or packets. You can get a huge pack or just a few pellets, depending on your needs. Since they’re compressed, you need to add water to rehydrate and loosen up the plugs before you can use them.

A tray of seed starting plugs.

They’re made from organic materials like coconut coir, peat moss, or tree bark. These materials create the perfect conditions for seeds to sprout.

Once you add water, they have a light and fluffy texture that gives roots plenty of room to stretch and grow. Some plugs include added ingredients like worm castings or compost to speed up root growth and feed young seedlings.

Some are made for hydroponic growing, while others are made to be transplanted into soil once seeds germinate. Either way, they’re all designed to help seeds sprout and produce healthy roots.

Seed starting plugs are sometimes called starter plugs, root cubes, grow cubes, or peat pellets. If you see any of these, they’re all essentially the same thing and most can be used interchangeably for starting seeds indoors.

Why Use Them?

There’s a lot to love about seed starting plugs! Here are some reasons why you might want to use them to start seeds for your garden this year.


One of the biggest reasons gardeners like seed starting plugs is that they’re convenient. The organic material is compressed and dehydrated, making the plugs easy to store. When you’re ready to use them, just add water and they’re ready to go.

Closeup of cucumber seedlings.

Unlike with a big block, you can use as many or as few as you need without having to worry about storing leftover mix.

Some pellets are wrapped in compostable netting, providing a pot and seed starting mix all in one. Talk about convenience! You don’t even need a pot with these, just set them on a tray, and when the plants are ready, the whole thing can be planted directly into the ground.

Less Mess

Another reason to use them is they’re less messy than big blocks or a bag of seed starting mix. There’s no scooping or stirring and you don’t need any extra buckets or containers, just the container you’re planting in.

Where Can you Get Them?

Seed starting plugs are easy to find. They’re widely available at home improvement stores like Lowe’s and Home Depot, garden centers, nurseries, and online from places like True Leaf Market and Amazon.

In the spring, when stores start putting out garden supplies, you can find them pretty much anywhere. I’ve seen them at big box stores like Walmart and Target and even grocery stores with other seasonal items.

Using Plugs to Start Seeds

Starting seeds with starter plugs is simple and fast. Choose a container and seeds and you’re ready to get started. You can use any kind of container you like to hold the plugs. Seed starting trays or small pots both work well.

If you’re using the kind of pellets that are wrapped in netting to create their own pot, all you need is a tray to set them on.

Seedlings in seed starting plugs.

What You Do

Put the plug in your container or seed tray and add water according to the directions on the package. The amount of water you need varies depending on what material the plug is made out of and how big it is.

Plugs expand in seconds and are ready to use right away.

Plant a single seed in each plug by poking a small hole and dropping the seed in. Some starter plugs have holes already, like these starter plugs from Amazon. Gently cover the seeds and press everything down gently to make sure the seed is in full contact with the growing medium.

Keep the seeds moist and warm while they’re germinating. A spray bottle is convenient for watering seedlings because it’s so gentle. Regular watering cans let out a lot of water at once. This works well for larger plants but the fast flow can easily displace seeds in the light and fluffy growing medium of seed starting plugs.

Sadie using spray bottle to moisten tray of seed starting plugs.

Heat mats are useful for keeping seeds warm and speeding up the germination process. This is especially helpful if you keep your house on the cooler side.

Humidity domes are good for keeping everything evenly moist and maintaining a warm temperature. This Jiffy Greenhouse Tray from Amazon includes seed starter plugs, a tray, and a dome.

What Else Do You Need to Start Seeds?

Good tools make the hard work of starting a garden easier and give you a greater chance of success. I’ve used all of these tools myself and can highly recommend them.

Seedling Starting Equipment

Hoss Germination Mat

Indoor Seed Starting Light Kit

SunGrow Black Gold Seed Starting Mix

Potting Mix

48 Cell Seed Starting Kit

Small Containers

Gardening Gloves

Garden Shovel

Spray Bottle

Watering Can

Garden Labels

High-quality equipment lasts for years and can be used over and over again. If you’re interested in learning more about how to build a seed starting setup we have an article all about it.

Most important of all, you’ll need seeds! We love Hoss Tools for seeds because they have a wide selection of high-quality seeds and they’re reasonably priced. You can find everything from fruits and vegetables to flowers and herbs. They have unique varieties like chocolate cherry sunflowers and classics like straight eight cucumbers.

A variety of seeds sold by Hoss Tools.

Caring for Seedlings in Plugs

After your seeds are planted, it’s important to care for them the right way to ensure the seeds grow into strong and healthy plants.


Once seedlings emerge, make sure they get plenty of light. Adequate light is very important for growing seedlings because plants get most of their energy from light. If they don’t have enough light, they won’t have enough energy to grow.

These adjustable hanging grow lights from Hoss are perfect for giving seedlings light indoors. The lights can be adjusted as seedlings grow without disturbing the plants.

Trays of seedlings under a grow light.


Water your seedlings once a day or every other day. The mix should look moist most or all of the time. When you notice the mix starting to look dry, that’s how you know it’s time to water.

When watering, the growing medium should be fully moistened but not sopping wet. It’s possible to overdo it. Seedling roots grow close to the surface, so they don’t need as much water as you might think. Too much moisture can cause problems like damping off and mold growth, so be careful not to overwater.

If you have more questions on how to provide the best care for young seedlings, we have a complete guide on how to grow healthy seedlings.

What to Do When Plants Outgrow the Seed Tray

It’s so exciting watching those little plants grow. At some point, they’ll start to outgrow the trays or little containers they were started in and need to be moved into bigger containers or planted outside in the garden.

Transplant seedlings when you see the first set of two true leaves. The first leaves that sprout often look a lot different than the true leaves of the plant. When you see the true leaves, that’s when you know it’s time to transplant.

Seedlings that have been potted up.

If the weather is right, you can plant seedlings directly outside in the garden. Harden them off first, then plant them right in their permanent growing location.

If your plants start to outgrow the plugs before it’s time to move them outside, pot up the seedlings by transplanting them into larger containers with potting soil. Keep those containers inside under a grow light until it’s time to harden them off and move them outdoors.

Get Ready to Try Seed Starting Plugs

Zinnia seedlings in seed starting plugs.

Are you convinced that you should try seed starting plugs this year? Anything that saves time and makes things easier is a win in my book!

For more seed starting tips and tricks, visit our Seed Starting page. We’ve put together a ton of resources for you, like how-to guides, planting tips, and product recommendations to help you have the best garden yet.

If you’re planting seeds, then chances are that you’ll also need more garden supplies and tools as the season progresses. Or maybe you’re looking for a unique gardening gift for a loved one. As always, Mineoppa Orchards is here to support you!