Do Microgreen Trays Need Drainage Holes?

by Lettuce Be | Last Updated: 06/02/2021

When growing microgreens in an indoor or hydroponic setting, you can grow nutritious salad greens and sprouts. Still, since they’re typically grown indoors, you might wonder whether they need drainage holes.

Is it necessary to drill holes in microgreens trays? As microgreens have shallow root systems, soil-based trays don’t require holes for adequate drainage. Waterlogging typically occurs with microgreens because they grow too fast. Microgreen trays can benefit from holes, however, because you can water the tray from beneath.

As microgreens do not require a drainage hole, they are highly versatile in the things you can plant them in. Here’s what you need to know about microgreen trays with holes.

Planters commonly require holes for drainage.

holes for drainageIn many cases, people believe that microgreen trays need a drainage function because gardeners are taught that indoor plants in a decorative container, like houseplant pots, need some way to drain away water to prevent mushy roots due to root rot. For this reason, a ceramic planter includes an ample drainage layer and a water tray at the bottom for catching the excess water that accumulates.

The rule is common to indoor gardening, so it may surprise many gardeners that microgreens do not need drainage saucers if they are planted in trays. Due to various reasons, microgreen trays do not need holes as a decorative planter does.

Why don’t microgreen trays require holes?

In contrast to a larger plant, growing microgreens do not require drainage holes. Among them are:

Growing and harvesting microgreens is quick. Generally, microgreens grow and are harvested in less than two weeks, which means they are not left in standing water long enough to cause root damage.

Shallow roots characterize microgreens. Seedlings that produce microgreens do not have deep roots that go to the bottom of the planting tray, so they should be protected from water that accumulates at the bottom.

A hydroponic grow mat is often used for microgreen cultivation. Growing seeds on hydroponic grow mats prevent seeds from becoming waterlogged, and they provide moisture retention and excellent drainage. Instead of holes, these mats provide proper drainage.

It is still a great idea to use microgreen trays even though they don’t have holes. Having a hole in the bottom of a tray with a layer of soil containing microgreens allows water from the tray beneath to be wicked away, eliminating the need to water them overhead.

Do microgreen trays need any other design elements?

When grown in a shallow tray, microgreens are one of the easiest crops to grow and can be germinated anywhere as long as the tray is flat. However, it is typically nursery-style growing trays made of plain, black plastic that growers use due to their durability and cost-effectiveness.

Because they are so simple to grow, growers who prefer to recycle can use many household items as microgreen trays, such as plastic take-out trays or disposable pie plates. In addition, microgreens are much more versatile as indoor crops than ever before since they don’t require drilling drainage holes.

A microgreen tray requires access to light, whether from an artificial setup or an intense window light. Sunlight requirements differ depending on the type of microgreen grown.

Sanitizing A Microgreen Tray

Even though microgreen trays don’t have drainage holes, you should sanitize them before use. The reason is that you will use the containers to sprout seeds, and the seedlings are pretty fragile when they first sprout.

A pathogen in the potting soil surface can damage seedlings, so it’s essential to sterilize microgreen trays between each growing period to prevent this damage. In addition, keeping soil-borne diseases from spreading is essential. Young seedlings cannot resist contact with the disease, whereas healthy plants can fend off soil-borne pathogens.

Let the tray air dry in a sunny area. Then, wipe clean and saturate the tray with hydrogen peroxide or another greenhouse cleanser before reusing it. If seed trays are appropriately sanitized, they will be recycled and used year after year, reducing the need to create new plastic for replacements.

A Comparison of Hydroponic and Soil-based Microgreen Trays

Hydroponic systems and soil-based systems are the two main methods of growing microgreens indoors. Microgreen seeds are grown in hydroponic systems using hydroponic mats holding extra water and nutrients on which the seeds can germinate. Due to their shallow deepness and the fact that microgreen seeds begin germination at the surface, they don’t require a soil-based medium to grow.

There are soil-based microgreen trays, but they are set up similarly to hydroponic systems, except the soil layer is higher in nutrients than the hydroponic grow mats. In addition, mycorrhizae are often added to seed starting soil to promote healthy roots and promote healthy seedlings.

The benefit of hydroponic microgreen trays is that they do not require holes for drainage like soil-based microgreen trays, but they also have the advantage of being soil-free, reducing the amount of mess caused by an indoor garden. As well as preventing soil-borne pathogens, it allows growers to control the quantity and type of nutrients they use.

How Many Seeds Do You Need?

The amount of microgreen seeds you need for a standard tray of 10-inches by 20-inches often gives you an inkling of how much you will need during the growing season. Therefore, before purchasing microgreen seeds, you should have an idea of how many you will need.

Whether you need more or fewer seeds for each tray will depend on how many trays you plan to grow. The average homeowner may only need a few trays and a few ounces of microgreens. Still, others who grow for commercial or culinary purposes are likely to plant several dozen ounces at a time.

Types of Microgreens That Can Be Grown In Trays

Microgreens can be grown in trays with or without drainage holes, and there are many different kinds. The following are some examples of microgreens that can be grown indoors in a microgreen tray:

You can use various microgreens to add different textures, colors, and flavors to sandwiches and salads. Besides garnishing your dishes with microgreens, you can also use them to boost the nutritional value of your food. Several types of herbs can be grown as microgreens, such as basil and mint, and these will provide a more delicate herb flavor than mature herbs would.

Growing microgreens from all kinds of varieties offer growers a tremendous amount of flexibility when it comes to cornering markets, as they may be able to offer a specific type of microgreen that no other growers are offering.


Growing microgreens is an excellent choice for anyone who wants to become familiar with indoor gardening, whether you’re going to grow them for your consumption or use in high-end culinary markets.

Drainage FAQ

What is drainage?

It’s a pretty straightforward distinction, and yet your pot with drainage holes means a world of difference in terms of potting, plant care, air circulation, avoiding extreme soil temperature, and maintenance.

Can I keep my plant in a pot without drainage holes?

Our answer is yes, but with caution.

What is a Drainage Hole?

Drainage holes make excess water to seep out of plant pots after watering, ensuring that water does not pool at the base of a flower pot, helping to protect sensitive roots from rot, fungus, and bacteria.

What is the best way to water a pot?

Whereas we usually recommend fully saturating plants in pots, allowing excess water to go out the bottom, when a plant in a pot without drainage, you want to make sure water slowly.

What are the pros of adding a drainage layer?

Adding a drainage layer like a layer of rocks allows excess water to get out of the soil more quickly and away from plant roots before being damaged.

What is a drainage layer?

A drainage layer uses drainage material such as a layer of pebbles, stones, or pumice to the bottom of a pot before adding a bit of soil.

What is the best way to drain excess water?

It is more convenient to use a pot with a detachable saucer.

What is the best way to drain water from a container?

Tiny holes at the bottom of the flower pot allow the water to drain out, and very little soil media is lost.

What is the best way to use excess water?

Place gravel in the bottom of the outer pot if the decorative pot is deep enough.

What is the difference between gravel and soil?

Instead of getting drained immediately, the extra water perches or gathers in the soil above the gravel.

What is the best way to find a self-watering container?

For more information, use a web search engine using the keywords “self-watering planter” or “self-watering container” or “earth box.”