3 Seed-Starting Systems for Starting Professional-Quality Seedlings

Molded plastic seedling trays are known as trays because their dimensions are approximately 10 inches by 20 inches.

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Cell flats (also known as plug flats) fit inside the seedling trays, leak-proof trays, or lightweight mesh trays, and are available in multiple sizes, identified by the number of cells in each flat.

The most common cell-flat sizes for veggie transplants are 50's, 72's, 128's and 200's. The cells in these flats are square and very closely spaced, to maximize the number of plants you can fit in your greenhouse.

For larger crops, there are cell flats with 38 or 24 cells per flat. The cells are larger, allowing for larger root balls, and the cells are round and spaced farther apart to allow for greater canopy development of the plants.

Another option is the 20-row seed flat, in which seeds are sown in channels to germinate, then "bumped up" or "potted up" into cell flats when their first true leaves appear. Seed flats are advantageous because they conserve seedling heat mat or germination chamber space.

Many growers consider this to be the most efficient way to start large numbers of seedlings at once.

Advantages. Trays and cell flats are the seed-starting method of choice on most large vegetable farms for several reasons:

• They are very quick to fill.
• They can be moved around easily.
• They are appropriate for use with mechanical transplanters.
• They are reusable for many seasons — if handled carefully and stored out of direct sunlight.

Disadvantages. Plastic trays and flats do have some drawbacks.

• They need to be stored and cleaned before they can be reused.
• Seedlings can become root-bound in the plastic cells, and there is some transplant shock when plants are removed from the cells.
• They will eventually wear out and need to be replaced. And when they do, they cannot always be recycled. And when they cannot be recycled, they usually end up in landfills, which has an environmental cost.

For sanitizing trays and as a means of disease prevention in your seed-starting program, we recommend a peroxide-based bleach substitute like OxiDate, which is an OMRI-listed disinfectant approved for use in certified-organic agriculture.

Whether or not plastic items such as trays, flats, and domes are recyclable nowadays is essentially dependent upon their composition, which will determine your local recycling center's policies, capabilities, and partnerships. If you use plastic seed-starting and plant containers, we encourage you to check with your local recycling center for more information on their recyclability.

Because of the scale of our operation, we do primarily use trays for greenhouse propagation and seed-starting. Here are the basic, crop-specific seed-starting practices with cell flats used here at Johnny's:

This is the 3rd time I ordered these seedling trays. I start my tomatoes and peppers about 6-8 weeks before they go outdoors. It's mid Feb. and my 8b zone ranges from 22-70 degrees until I plant outside early to mid April. I use a lightweight planting mix and these trays hold the mix in my 10/20 trays. I bottom water and the slots in the trays allow proper watering.
I have reused some of these trays 3 times so far and have had no problems doing so. They are thin. They hold soil. They are slightly tapered and release my plants when I invert the tray supporting the plants with my fingers. If you are looking for trays that are strong, heavy duty, can be hosed out at the end of the season...these aren't them. Everything seems to cost more than it should but I'm not running a commercial operation and I don't drop or throw these around. I'm satisfied with the price/value/point and they serve my needs. I'm glad they can be shipped to my door and I don't have to search and settle for what I can find or use paper cups or used food containers as my only source of containers ( I do transplant some into large yoghurt containers tho...lol.

Cell propagation trays

Start your seedlings in cell trays for space-saving advantages. Cell plug trays are the perfect tool for market gardeners that want to start more market crops at once. Another advantage is that you will waste less growing media starting out your seeds and then up-potting the successfully germinated starts into new pots. 

What Size Cell Tray Should I Use?

Our propagation trays are available in several configurations and are made of extra-strong, BPA-free, food-safe plastic backed by a 1-year warranty. Discover which size cell tray will work for your greenhouse or garden plants. The cell tray guide below will help you in making the decisions about which tray is best for your operation. Or take our Garden Seed Tray Style Quiz.

Whether you are a homesteader growing food for your family or a large-scale production farm looking to streamline your transplanting process with trays that will last season after season. If you need more help making a decision please check out our article on Selecting the Right Cell Tray for Seed Starting.

6 Cell Individual Seed Starter Trays

Our newly redesigned 6 cell trays have large 5/8 inch drainage holes on the bottom making it easy to remove your plant starts. They also make use of air pruning technology with long vertical slits on all 4 sides to prevent root circling in your seedlings. For easy color coding and tracking or your starts we are super excited to also offer our 6-cell trays in 5 cheerful colors. These are great for gardeners who will be starting a small amount of lots of different varieties as you can remove each type as it is ready without disturbing all the other starts that are sharing its heavy-duty deep tray  bottom watering tray. 12 fit in each tray. 

32 Cell Seed Starter Trays

The 32 cell plug propagation tray inserts are the largest seed starting cell tray size, measuring 2" x 2". The added space allows plants to develop their canopy and allows them to stay in the cells of the tray longer than they would in a tray with less volume of potting soil. When used in conjunction with our seed starter insert pots, these are typically the best trays for seed starting for the home gardener. 

Are you interested in learning more about Leak-Proof Seedling Trays? Contact us today to secure an expert consultation!

50 Cell Seed Starter Trays

These 50 cell propagation trays give ample room for seedlings to develop while allowing for a larger number of seeds to be planted in the 10”x 20” space. Plants grown in these plug trays will be less likely to become root-bound if unsettled Spring weather delays your planting schedule. This size also allows for larger canopy development in the seedling. 

72 Cell Seed Starting Trays

The 72 Cell trays are the most popular choice amongst market gardeners. They are a good balance between space for growing and the number of seedlings per cell in the tray. Each of the individual cells is 1.5" square and 2.25" deep. This sizing is perfect for starting many different plants including vine crops. These 72 plug trays are compatible with the heavy-duty deep tray for bottom watering.

Air Prune Propagation Tray 72 Cell 

Get the air pruning benefits of soil blocking without the mess! These farm trays allow for airflow above and below the soil, so newly established seedlings get optimal growing conditions for a strong start. Our newest 72 cell air pruning tray can be used to grow everything you would use a traditional 72 cell tray for but can also keep plants growing for longer without root circling becoming an issue. These also fit nicely in our heavy-duty deep tray . 

128 Seed Propagation Trays

These 128 Cell Trays are a great choice for seed starting trays if you wish to start row crops or many baby greens. This configuration is ideal for starting many seeds but is not meant for crops that need to be grown in protection for more than a few weeks. Each of the cells is 1" square and 2.25" deep. You will be able to plant 78% more seedlings with one tray than the more common 72 Cell starter tray.

These 128 plug trays are compatible with the heavy-duty deep tray for bottom watering. You will want to up-pot your seedlings from this size into larger pots or grow bags if you do not plan to transplant outdoors for an extended period of time to prevent seedlings from becoming root-bound.

200 Cell Propagation Trays

These 200 Cell Trays are excellent seed starting trays if you want to be economical about growing cole crops, lettuces, and other small-seeded crops. You will be able to start ~2.8 times as many seedlings with one tray as you would with a 72 cell tray. Each of the cells is 0.75" square and 2.25" deep.

Interested in learning more about seed starting? Be sure to check out our Seed Starting Blogs.

Why Should You Use Seed Starting Trays

When plants are healthy from the start, they're more likely to grow vigorously and look their most beautiful when fully grown. Plant trays and flats provide a safe place for young plants while they sprout, making them a must for casual and expert gardeners.

Some people also use planting trays for permanent indoor growing to produce a beautiful, lush environment. Unlike large, potentially messy outdoor pots, these trays are made to be used inside with leak-proof designs. They're also very affordable, saving you money compared to regular outdoor pots.

Propagation Trays, Seed Trays and More

Shop dozens of bulk plant trays that are made for the way you garden.

Our trays are available in three different thicknesses to meet all budgets and demands. These standard-size garden trays are perfect for inserts that help you get a jump on spring as a seed-starting tray, or fill them up with soil and seeds for a handy fodder tray. The heavy-duty open design allows for easy community watering, and they're available with or without drainage holes. You can get colored trays for an extra pop or some daisy trays for your bedding plants.

Make sure to check out our lineup of inserts, propagation trays, black form trays, plug flats, carrying trays and humidity domes. They're made of durable materials such as thermoformed plastic and terracotta to prevent leakage.

Not a fan of plastic? We have biodegradable tray pots, mesh drainage trays, plant irrigation waterbeds and much more in various shapes and sizes. Grow your plants while respecting the environment with trays that make the most of every resource used to grow your garden.

You can get a giant garden tray to use as an irrigation table for potted plants or a seed-starter kit that simplifies those crucial early growth stages. There are kits for organic seed starting, kitchen herbs, high-humidity seedlings and much more.

The Best Plant and Seedling Tray Collection

Greenhouse Megastore supplies hobby gardeners and commercial planters with the planting trays, expertise and fast shipping they need to grow amazing flora. Whether you need a seed starting tray for your greenhouse grow table, a propagation tray to place on the windowsill or a flat to showcase plants during a farmers market, we have the right trays in stock.

You also get the best deal on planting trays and seed starters. Greenhouse Megastore will match any online competitor's advertised price and give volume discounts on many items as part of our Price Match Policy. Contact our team today to discuss your planting goals and how our selection of Greenhouse Megastore trays can help you meet those goals.

For more Seedling Trays Priceinformation, please contact us. We will provide professional answers.