---
title: "Silicone microgreen mats: crops, cleaning and yearly cost"
description: "Silicone microgreen mats hold no medium, so watering works differently. See which crops suit them, how to clean them, and what they cost over a year."
url: "https://microgreensguru.com/blog/silicone-microgreen-mats/"
lang: "en"
published: "2026-10-09"
modified: "2026-11-09"
author: "Cal Hewitt"
image: "https://microgreensguru.com/og/blog-silicone-microgreen-mats.jpg"
alternates:
  es: "https://microgreensguru.com/es/blog/tapetes-silicona-microgreens.md"
---

# Silicone microgreen mats: crops, cleaning and yearly cost

[Cal Hewitt](https://microgreensguru.com/about/cal-hewitt/) Published October 9, 2026 Checked November 9, 2026

- growing
- equipment
- growing medium

![Two hands lifting a pale grey silicone mat topped with dense green microgreens, white roots hanging through its holes above a black tray](https://microgreensguru.com/images/blog/silicone-microgreen-mats.jpg)

According to its maker, a reusable silicone mat can work for broccoli, radish, kale, cabbage and other brassicas, and, on the maker's crop-life estimate, it can cost well under half of what [hemp](https://microgreensguru.com/go/medium-grow-mats/) or coco mats cost over a year of weekly trays. The catch is that it suits some seeds much better than others, and it needs a different watering routine.

On The Grow says silicone holds no nutrients and does not retain moisture like soil or fiber mats, so its instructions call for bottom watering with a nutrient solution. It also matches hole size to seed: 1.2 mm for small and medium seeds, 1.7 mm for larger ones.

## Which hole size fits your seed

Start with the seed, because the hole size decides whether the crop stays on the mat. On The Grow, a maker of silicone mats, says its [1.2 mm mat](https://onthegrow.net/products/silicone-grow-medium-10x20) suits broccoli, radish, kale, cabbage, kohlrabi and most brassicas. Its 1.7 mm large-hole version is meant for sunflower, peas, wheatgrass, radish and melon, according to the maker's [FAQ](https://onthegrow.net/pages/faq). Radish appears on both lists, so you can start it on either size.

![Macro view of a grey silicone mat with a regular grid of tiny round holes and a few small round seeds resting in some of them](https://microgreensguru.com/images/blog/silicone-microgreen-mats/macro-of-silicone-mat-holes-with-brassica-seeds.jpg)

If you grow mostly brassicas, buy the 1.2 mm mat. If sunflower or wheatgrass is your main crop, buy the 1.7 mm. If you grow both, buy one of each and keep notes on which tray went on which mat. The maker says broccoli and radish are the forgiving crops to start with, and that is a sensible place for your first tray.

Seedmart Australia, another seller, lists pea tendrils, radish, broccoli, arugula, basil, cabbage and kohlrabi as workable. Both sellers say Swiss chard, beets and cilantro can be difficult. On The Grow adds fennel, buckwheat, borage, nasturtium and marigold to its list of harder crops. These are the sellers' reports, so treat them as a warning label rather than a ban. If one of those crops is your main income, run a single test tray before you buy a stack of mats.

## Seeds that need a workaround

Fine seeds can fall through the holes. Seedmart's listing recommends a paper towel under the silicone for amaranth, mustard and other fine seeds. On The Grow reports some success with amaranth on its 1.2 mm mat when the tray sits on a 75°F heat mat, but it also lists many very fine seeds as difficult. For amaranth, mustard and other fine seeds, put the towel down first and keep the mat on top of it.

Mucilaginous seeds, the ones that turn gel-like when wet, need different handling. On The Grow says basil, chia, flax and arugula should not be soaked. Spread them dry and mist lightly. Skip the pre-soak for these four.

Peas are the other special case. Their roots tangle deeply, and On The Grow recommends a bare mesh tray for peas. If you want to put peas on silicone anyway, the maker says the 1.7 mm mat is the better of the two. Growers on Reddit have reported both sides: [one](https://www.reddit.com/r/microgreens/comments/5y1bsc) had broccoli, radish and pea crops work on a 7 x 14 kit, while others described pea mold and cleanup trouble, and sunflower that did not attach well to some mesh trays. Those are individual reports, not a rate, so read them as reasons to start small.

## How to water a mat that holds nothing

Soil and fiber mats store water and, in soil's case, nutrients. Silicone does neither well. On The Grow reports watering from below with a nutrient solution at 0.5 fluid ounces per gallon and a pH of 5.5 to 6.0. Those are the maker's numbers for its own product, and you should follow the instructions that come with whichever mat you buy.

![Hands pouring water from a small pitcher under a flat silicone mat of young seedlings in a black tray](https://microgreensguru.com/images/blog/silicone-microgreen-mats/pouring-water-into-the-bottom-of-a-tray-under-a-silicone-mat.jpg)

How often to water is a separate question. The Virginia Cooperative Extension [microgreen production guide](https://www.soiltest.vt.edu/content/pubs_ext_vt_edu/en/SPES/spes-756.html) says bottom watering in 10 x 20 trays can run from once every two days to several times a day, depending on the growth stage and the substrate. It notes that hemp holds more water than burlap and so needs watering less often. For silicone, use the seller's instructions for your exact mat and crop, then keep to them through the first crop.

So, treat the first tray as your own trial. Record how much solution you add, how often, and what the tray looks like at each check. Change one thing at a time on the second tray.

A word on timing. The Penn State pea and radish study, [published in Frontiers in Plant Science](https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1229157/full), harvested five days after sowing. That work used soil and coir, not silicone, so do not copy its days into a silicone schedule. Cut when your own crop reaches the stage you sell or eat, and write the day down.

## What to do this season

Pick the hole size from your main crop. Buy one [silicone mat](https://microgreensguru.com/go/medium-silicone-mats/), confirm price and stock before you pay since they change, and ask for the food-contact documents if you sell. Run broccoli or radish first, water from below, and write down your solution amount, your watering schedule, your harvest day and your cleaning steps.

If you want to know whether the mat beats your current medium for yield, run two trays side by side using the same seed lot, density, light, water and harvest day, and record fresh weight and usable harvest. Your own scale gives you the comparison for your setup. Compare the mats on sale in the [growing medium review](https://microgreensguru.com/product-reviews/growing-medium/) before you pick a brand.

## Harvest and clean on the same day

Cut the stems just above the mat. On The Grow says roots grow through the openings rather than forming a root mat inside the silicone, and that roots, stems, seed hulls and debris are scraped off after the cut. On The Grow says they come off more easily if you clean the mat right after harvest, before the root material dries.

![Grey silicone mat under a running kitchen faucet over a white sink with bits of root and seed hull washing off, a cut tray of stubble on the counter](https://microgreensguru.com/images/blog/silicone-microgreen-mats/silicone-mat-rinsed-under-a-faucet-with-roots-and-hulls-washing-off.jpg)

The maker's cleaning steps, from its [cleaning page](https://onthegrow.net/blogs/microgreens/how-to-clean-sanitize-microgreen-trays-reusable-mediums), are short:

- Scrape the roots and debris off with a scraper or your hands.
- Wash with warm water and a mild food-safe dish soap.
- Sanitize with boiling water for two minutes.
- Optionally soak in 3% hydrogen peroxide for 10 to 20 minutes.
- Skip brushes, abrasive scrubbers and the dishwasher.

Those instructions are specific to that maker's mat. They differ from general extension advice. University of Minnesota Extension describes a wash, rinse, sanitize and air-dry sequence for reusable hydroponic parts, and gives chlorine bleach at [50 to 100 ppm for food-contact surfaces](https://extension.umn.edu/food/preparing/cooking-at-home/sanitizing-equipment-and-food-contact-surfaces). On The Grow says not to use bleach or chlorine cleaners on its silicone. Follow the maker's rules for the mat in your hands, and use the extension sequence of wash, rinse, sanitize and air dry for everything else in the tray stack.

One more instruction from the maker: mats with fiberglass reinforcement must not be cut, punctured or resized, because damage to the outer layer can expose the fiberglass. Retire a mat that tears or flakes.

For a routine, do the first tray by the instructions, then write down each step and its time. Repeat the same sequence on every tray. Mold depends on moisture, seed density, airflow, seed quality and cleaning, and a reusable mat does not remove any of those. On The Grow itself says poor cleaning can contribute to mold and damping off. For more on cleaning habits across media, see [reusing medium and trays](https://microgreensguru.com/grow-microgreens/reusing-medium-and-trays/).

## Food-contact claims: read the label closely

A silicone mat touches your crop, so the material matters. The FDA rule that covers repeated-use rubber articles, including silicone elastomers, is [21 CFR 177.2600](https://www.law.cornell.edu/cfr/text/21/177.2600). It sets extraction limits and requires articles to be thoroughly cleaned before first food contact. It is a materials standard, not an FDA product certification.

On The Grow says its 1.2 mm standard mat has been third-party tested to that rule and to Germany's LFGB, and that "FDA compliant" means tested against FDA standards rather than FDA approved. It also says that testing language applies to the 1.2 mm mat only. Its 1.7 mm version is a separate manufacturer's product without the same language, per the maker's [FAQ](https://onthegrow.net/pages/faq).

If you sell what you grow, ask the seller of any mat, at any hole size, for the laboratory report that names the tested material, the manufacturer, the test method and the intended use. FDA says a manufacturer may provide a [letter of guaranty](https://www.fda.gov/food/packaging-food-contact-substances-fcs/determining-regulatory-status-components-food-contact-material) for the intended food-contact use, which is a reasonable thing to request.

## What a year costs, with the arithmetic

Take one 10 x 20 tray a week, or 52 trays a year, and count only the medium. Seeds, trays, nutrients, sanitizer, power, labor, shipping and tax are left out, and all prices were displayed on November 9, 2026.

![Neat stack of clean grey silicone mats beside a taller loose pile of brown hemp mats on a kitchen counter](https://microgreensguru.com/images/blog/silicone-microgreen-mats/stack-of-silicone-mats-beside-a-pile-of-brown-hemp-mats.jpg)

The On The Grow 1.2 mm mat was $15.97. The maker estimates 20 to 30+ crops per mat, which is its own estimate, not an independent durability trial. At 20 crops that is $15.97 divided by 20, or $0.80 a tray. At 30 crops it is $15.97 divided by 30, or $0.53 a tray. Fifty-two trays need 2.6 mats at the low estimate and 1.73 at the high one, which works out to $41.52 or $27.68. Because you buy whole mats, your actual outlay is three mats ($47.91) at the low estimate or two mats ($31.94) at the high one.

Now the disposable side:

- Urban Farmer hemp mats, 5-pack at $19.25: $3.85 a tray, or $200.20 for 52.
- The same hemp at the 25-pack price of $77: $3.08 a tray, or $160.16.
- The same hemp at the 100-pack price of $270: $2.70 a tray, or $140.40.
- Envelor coco mats, 10-pack at $29.99: $3.00 a tray, or $155.95 for 52.

Against the 5-pack hemp, three silicone mats save $152.29 in the first year ($200.20 minus $47.91). Against the cheapest hemp tier, the saving shrinks to $92.49 at the low estimate and $108.46 at the high one. Against coco it is $108.04 at the low estimate. For soil, [Microgreens Guru's September 12, 2026 calculation](https://microgreensguru.com/blog/best-potting-soil-for-microgreens/) put four potting mixes between $2.37 and $5.55 per 10 x 20 tray, depending on the bag and fill depth.

The silicone number is only fair if you add the nutrient solution the maker calls for. Add your fertilizer cost per tray, your cleaning time, and the cost of a spare mat if one tears. Then divide your own mat price by the crops it actually carried, and compare that with what you pay per crop now.

## Frequently asked questions

**Can I cut a silicone mat to fit a smaller tray?** Not a fiberglass-reinforced mat. The maker says damage to the outer layer can expose the fiberglass. If you grow in a smaller tray, buy the size made for it; On The Grow lists 10 x 10 and 7 x 14 as well as 10 x 20.

**Is the 1.7 mm mat tested the same way as the 1.2 mm?** The maker's FDA 21 CFR 177.2600 and LFGB testing language covers the 1.2 mm standard mat, and the 1.7 mm is a separate manufacturer's product. Confirm the exact hole size and request documents for that version.

**Does a silicone mat prevent mold?** Grower reports describe mold on hemp, silicone and other media, so the mat does not settle the question. Seed density, airflow, moisture, seed quality and cleaning all play a part. Compare matched trays and record any visible mold and the weight of crop you discard.

**How long will one mat last?** The maker estimates 20 to 30+ crops. Replace it at the first tearing, flaking or exposed reinforcement, and ask the maker for its cycle-testing records.

## The short version

If your crops are brassicas, radish, sunflower or wheatgrass, a silicone mat is worth one trial tray, and the yearly arithmetic favors it over hemp or coco on the maker's crop-life estimate. If your main crops are on the difficult list, or you need peas, test first. Either way, keep your notes from the first tray; they are the figures that will tell you whether the mat pays off for you.

## Sources

Prices, stock and specifications are as the linked pages showed them on 2026-11-09.

- [1.2 mm mat](https://onthegrow.net/products/silicone-grow-medium-10x20)
- [FAQ](https://onthegrow.net/pages/faq)
- [one](https://www.reddit.com/r/microgreens/comments/5y1bsc)
- [microgreen production guide](https://www.soiltest.vt.edu/content/pubs_ext_vt_edu/en/SPES/spes-756.html)
- [published in Frontiers in Plant Science](https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1229157/full)
- [cleaning page](https://onthegrow.net/blogs/microgreens/how-to-clean-sanitize-microgreen-trays-reusable-mediums)
- [50 to 100 ppm for food-contact surfaces](https://extension.umn.edu/food/preparing/cooking-at-home/sanitizing-equipment-and-food-contact-surfaces)
- [21 CFR 177.2600](https://www.law.cornell.edu/cfr/text/21/177.2600)
- [letter of guaranty](https://www.fda.gov/food/packaging-food-contact-substances-fcs/determining-regulatory-status-components-food-contact-material)
- [Microgreens Guru's September 12, 2026 calculation](https://microgreensguru.com/blog/best-potting-soil-for-microgreens/)

## Keep reading

- Growing guides

    ### Hydroponic and soil-free microgreens: the same swap costs a third of the pea crop and gains on radish

    In one replicated trial, moving from peat-perlite to coir cost pea 32.7 percent of its yield and gained radish 4.5 percent. Two extension services cannot even agree whether a mat counts as hydroponic, and the word is doing two jobs at once.

    [Read Hydroponic and soil-free microgreens: the same swap costs a third of the pea crop and gains on radish](https://microgreensguru.com/grow-microgreens/hydroponic-and-soil-free/)
- Growing guides

    ### Can you reuse the medium? Reuse clean loose coir, replace the mat, never reuse a failed tray

    Reuse loose coir or peat off a clean tray, screened and refreshed half with new mix, and throw fiber mats away. The one pathogen study covers 4 of the 12 materials an extension service names, so test reuse on one tray before you scale it.

    [Read Can you reuse the medium? Reuse clean loose coir, replace the mat, never reuse a failed tray](https://microgreensguru.com/grow-microgreens/reusing-medium-and-trays/)
- Growing guides

    ### What to grow microgreens in: the medium barely moves yield and roughly doubles nitrate

    Every medium comparison argues about yield, where the honest spread between reasonable media is 13 to 16 percent. The measurement that moved most is nitrate, which moved about twofold across three crops in two independent trials, and not always in the same direction.

    [Read What to grow microgreens in: the medium barely moves yield and roughly doubles nitrate](https://microgreensguru.com/grow-microgreens/soil-and-medium/)
- The journal

    ### Are Grow Lights a Fire Hazard? A Checklist for Tonight

    Wondering if your grow lights are a fire hazard? Add up the actual watts and amps on your rack, then check them against your circuit and timer limits tonight.

    [Read Are Grow Lights a Fire Hazard? A Checklist for Tonight](https://microgreensguru.com/blog/grow-light-rack-electrical-safety/)