Should Microgreen Trays Have Drainage Holes?

by RightFit Gardens | Last Updated: May 5, 2021

You can grow microgreens or sprouts as nutritious salad greens and sprouts indoors or hydroponically, but since they’re generally cultivated indoors, you’ll wonder whether it’s necessary to drill drainage holes.

Those with a potting soil mix medium do not need holes for drainage because microgreens have shallow root systems as well as typically growing too fast to get waterlogged. However, holes in the tray can be useful for watering from underneath.

The fact that microgreen trays do not have drainage holes means microgreens work well in a wide range of media. Read on for more information about the holes in microgreen trays.

Do Most Planters Have Holes?

holes for drainageIt is common knowledge that microgreen trays must contain drainage holes as people are taught as children that plants in a decorative container or material like a decorative planter must have some means to drain extra water away from their roots to prevent plant root rot and plant death. Typically, plastic planters will have drainage holes and a water tray positioned beneath them, to collect excess moisture and provide air circulation. To allow the layer of soil of a potted plant to recover from excess water, holes must be present at the bottom of the container that allows stagnant water to drain away from the plant. Most pots come with a drainage saucer or a detachable saucer to collect the water that drips from these holes.

A careful gardener is used to this rule when they are gardening indoors, so it surprises them to learn trays of microgreens don’t require any drainage material. There are a few different reasons for this, but microgreen trays do not need the holes that a cheap planter may require. Others say that growing plants in pots without drainage holes is possible but only with a drainage layer of rock, gravel, pebbles, activated charcoal, and other coarse materials. Double potting can work wonders, too. Different types of plants are grown in a pot liner when double potting is used.

Why Don’t Microgreen Tray Have Any Holes?

Several different reasons contribute to the reason microgreens do not need drainage holes while larger plants do. Here are a few of them:

While holes in microgreen trays are not necessarily necessary, they can still be useful in some cases. Holes in a tray with microgreens that are grown in quality potting soil can allow water to drain from under the tray, reducing the need for overhead irrigation of the microgreens.

What Do Microgreen Trays Require?

The microgreens crop is easy to grow and can be grown in almost any container for planting as long as the tray is flat and shallow. Black nursery-style growing trays are the kind preferred by most growers due to their durability and relatively low cost.

In addition to their ease of growing, those who prefer recycling can use a variety of household objects to create a microgreen tray, from takeout trays to pie plates. Because microgreen trays do not require drainage, this greatly enhances their versatility as an indoor crop.

It is important to expose microgreen trays to light, either from an artificial setup or from a bright window. The amount of sunlight required for strong growth depends on the species of microgreens being grown.

How To Sanitize Microgreen Trays

Despite the absence of drainage holes, microgreen trays are still required to be sanitized before they are used for sprouting. This is because seedlings are extremely fragile when they first sprout.

Microgreen trays should be sterilized between growing periods to prevent the soil-borne disease from spreading. While older plants may be able to withstand contact with the soil-borne disease, young seedlings are easily overwhelmed when that contact occurs.

The microgreen tray can be sanitized by spraying it down with hydrogen peroxide or another greenhouse cleaner, then drying it in the sun so that it can be used once more, therefore reducing the need to generate new plastic each year for replacements.

Hydrophonic Vs. Soil-based Microgreen Trays

There are two main methods of growing microgreens in indoor trays: hydroponics and soil-based systems. Hydroponic systems place the seeds in a mat that holds water and nutrients, allowing them to germinate. Since microgreen seeds grow shallowly and germinate from the soil’s surface, this type of medium isn’t necessary for their growth.

There are also soil-based microgreen systems available, which are set up similarly to hydroponic systems except that the soil utilizes high-nutrient commercial potting mix instead of hydroponic grow mats. Mycorrhizae are often added to the soil layer to encourage the signs of root growth.

Both soil-based and hydroponic microgreen trays do not require holes for proper drainage, although hydroponic microgreen trays have the benefit of being soil-free, allowing growers to concentrate their attention on nutrient input and preventing soil-borne pathogens.

How Many Seeds Do You Need?

The amount of microgreen seeds needed for a standard 10-inch tray is approximately one ounce, so that gives you a good guideline for how much microgreen seed you’ll need throughout the growing season. Since microgreen seeds have a limited shelf life, it is important to know how many you will need before purchasing them.

The number of seeds you need for microgreen trays will depend on how many trays you plan on growing. For household use, a couple of seeds per tray will suffice, but other growers may need to plant several dozen ounces of seeds at a time.

What Microgreens To Grow

Growing microgreens in trays with or without drainage holes are possible with several different types. Here are just a few of the types of microgreens you can grow as indoor plants in a microgreen tray:

These seedlings can be used to replace older herbs like mint for a more delicate herb flavor. Since there are so many varieties of microgreens, they are great in salads and sandwiches. Microgreens are also great as a garnish for roasted meats and soups.

Growers can corner markets by producing a specific subtype of microgreens that other local growers aren’t producing due to the wide variety of healthy plants that can be grown as microgreens.

Indoor Gardening and Microgreen Trays

Growing microgreens can be a great alternative in the kitchen or a great way to supplement your family’s diet. Anyone interested in learning about indoor gardening can start with microgreens.