Microgreens trays and kits: 1020 tray sizes, holes or no holes, media, kits and DIY

The 1020 tray: the standard size

"1020" is the trade name for a greenhouse flat about 10 inches wide and 20 inches long. Penn State Extension recommends "1020 (standard) greenhouse trays" for microgreens, the University of Maryland Extension gives its seed rates per 10 × 20-inch flat, and Johnny's Selected Seeds ran its 2017 microgreen yield trial on 1020 flats. Because seed rates, lids, mats and racks are all sized to it, the 1020 is the easiest tray to plan around.

The name is nominal. Actual trays vary a little by maker and wall thickness. One US maker lists its shallow 1020 microgreen tray at 21 × 10¾ × 1¼ inches outside, or about 53 × 27 × 3 cm, and also sells a standard 1020 about 2.5 inches (6.4 cm) deep. For seed rates, this guide uses the nominal 200 square inches, which is 200 × 6.45 = 1,290 cm². Check that trays you plan to nest together come from the same maker and are the same depth.

Trays with holes and trays without holes

Most microgreen growers use two trays together. The top tray has drainage holes and holds the growing medium and seed. The bottom tray has no holes and holds water. Pour water into the bottom tray and the medium draws it up through the holes. Penn State recommends this kind of sub-irrigation because it keeps leaves and stems dry, which it says is important for avoiding disease, and the University of Maryland Extension says to keep the medium moist but not saturated.

A tray without holes is also the usual blackout cover: turned upside down over the sown tray, it keeps the seed dark and humid, and with a weight on top it presses large seeds such as pea and sunflower into the medium, as Penn State suggests. Mesh trays are a third type. They have many small holes for fast drainage and suit mats, hydroponic racks and bottom-watering systems. One maker's mesh 1020 has 3.4 mm holes and is designed to sit inside a no-hole tray of the same depth.

• Tray with holes: holds the medium and seed; lets water in from below and drains the excess
• Tray without holes: holds water under the growing tray; doubles as a blackout cover
• Mesh tray: maximum drainage; for mats, soil blocks and flood-and-drain racks
• Humidity dome or lid: keeps germinating seed moist; lift it once shoots are up

Tray sizes compared

Smaller trays suit a kitchen, a single variety or a trial of a new seed. Larger trays suit a steady weekly supply. The table lists common sizes with example dimensions from manufacturer listings and Penn State, and scales the University of Maryland and Penn State seed rate of 10–15 g per 1020 tray to each tray's area. For example, a 5 × 5-inch tray is 25 square inches, one-eighth of a 1020, so it takes 10 ÷ 8 = 1.25 g to 15 ÷ 8 = 1.9 g of small seed.

Depth, material and care of trays

Microgreens need little depth. The University of Maryland Extension suggests 1 to 1½ inches (2.5–4 cm) of soilless mix, and UF/IFAS suggests a container 2 to 3½ inches (5–9 cm) deep that is food grade and clean. Shallow trays of about 3 cm suit mats and thin layers of mix, and make it easier to get scissors under the leaves at harvest. Deeper trays hold more mix and more water, which helps in hot, dry weather.

One US maker lists its solid trays as polypropylene (plastic #5) and its mesh trays as polyethylene (#2), both BPA-free and food safe; look for the same when buying locally. The same maker notes that long exposure to direct sunlight degrades its trays, so store trays out of the sun when they are not in use. Wash trays between batches, rinse off any detergent, and let them dry fully. Penn State recommends fresh growing medium for each cycle to reduce damping-off, and a clean tray is part of the same routine.

Growing media for trays

The medium is the second half of the tray decision. The University of Maryland Extension recommends a lightweight soilless mix and adds that a 50:50 blend of screened plant-based compost and potting mix saves money. In India, cocopeat is the usual base. The ICAR-IARI study by Priti and colleagues (2022) tested three blends of cocopeat, vermiculite and sand and found 2:1:1 held water best. Mats of hemp, jute or coco coir replace loose media in soil-free growing.

Media affect yield. Kyriacou and colleagues (2020) grew coriander, kohlrabi and pak choi on five media with the same nutrient solution and recorded 2.96 kg per m² on peat moss, 1.65 on coconut fibre and 1.18–1.31 on synthetic pads. The MANAGE handbook from Hyderabad also tested wet tissue paper, which it describes as quick to set up. For a first tray, a soilless mix or cocopeat blend is the most forgiving.

Microgreen kits compared

A kit bundles trays, a growing medium and seed, and sometimes a lid, a mister or a light. It saves the effort of sourcing parts, and it suits a first attempt or a gift. The trade-off is that the seed and media in a kit run out after a few trays, and refills may be sold only by the same seller. Before buying, check what refills cost and whether the trays are a standard size, so that you can use any seed and media later. A kit with standard 1020 or 1010 trays stays useful long after its seed runs out.

The table describes the common kit types without naming brands. Whichever you choose, check four things: that the seed is labelled untreated, that the trays are food-safe plastic, that there is a tray without holes for bottom watering, and that the kit includes, or leaves room for, a way to keep the seed dark for the first few days of germination.

DIY trays from what you already have

Any clean, food-grade container 5–9 cm deep can grow microgreens, following the UF/IFAS guidance. Cut or punch drainage holes in the base of one container and stand it in a second, identical container that has no holes. Takeaway boxes, bakery clamshells and shallow food-storage boxes all work. Wash them well first, and do not use containers that held paint, chemicals or motor oil.

A DIY setup costs almost nothing, and it is a good way to test whether you will keep growing before buying trays. Its limits are size, since small containers give small harvests, and durability, since thin takeaway plastic cracks after a few washes. For a weekly supply, most home growers move to one or two standard trays once they know which varieties they eat.

• Two identical food containers, 5–9 cm deep: one with holes, one without
• A heated skewer or a drill to make drainage holes across the base
• A lid or a third container, upside down, as the blackout cover
• Soilless mix, cocopeat or a few layers of tissue paper
• Seed at the scaled rate: about 2.3–3.5 g of small seed for a 15 × 20 cm box

How many trays you need

Plan by harvest, not by sowing. A brassica such as radish, mustard or broccoli takes about 8–14 days in the Johnny's and ICAR-IARI trials, and a tray is cut once. For a steady supply, stagger sowings. If a tray takes about 14 days and you eat one tray a week, two trays sown 7 days apart keep the supply going: 14 days ÷ 7 days = 2 trays growing at any time. Add one tray without holes per growing tray, for watering and as a cover.

More trays do not mean more seed per tray. Keep to the seed rate for the tray size, because overcrowding reduces quality. Dubey and colleagues (2026) found that bacteria, yeasts and moulds on cress, rocket and pea rose as seed density increased. If you need more greens, add a tray rather than sowing an existing tray more thickly, and keep a note of the seed weight and harvest day for each tray so you can repeat what worked.

Fresh microgreens in Pune

Trays and kits are the way to start growing your own. If you would rather skip the trays, Garden & Acre delivers fresh microgreens across Pune and Pimpri-Chinchwad from our own supply chain, as a weekly box for homes or as regular supply for restaurants, cafés and hotels. We do not sell trays, kits or seeds. Orders are taken on WhatsApp, where we share the varieties available that week and the prices.

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