The best size cell plug seed trays for you to choose will be dependent on a few factors. We will go over the different options to help you select the best for you. Consider first, what is your intent in seed starting?
If you want to learn more, please visit our website MARSHINE.
Quickly review some of these seed starting questions.
Check out The Ultimate Growing Tray Guide video for a look at how these trays are commonly used.
4 Cell Seed Starting Trays
Our brand new larger 4-cell plug inserts are deeper for growing varieties of crops that need a little more room. Eight of these removable inserts fit in a Bootstrap Farmer .
6 Cell Seed Starting Trays
Our 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 or 6 to a tray.
Shop Bundles & Kits here.
32 Cell Seed Starting Trays
The 32 cell plug propagation tray inserts are the largest cell seed starting tray size that Bootstrap Farmer carries, measuring 2" x 2". The larger size makes them perfect for canopy development of crops. You can also use this size as an insert tray to hold our 2.5" seed starting pots.
These cell seed tray inserts can be used in two ways. Directly plant into these cell inserts with deep drainage holes with Rockwool cubes, soilless media, or soil mediums. The entire tray can be bottom watered using a shallow tray with no holes.
Another way these insert trays are used is as a holder for these seed-starting pots. Seamlessly designed to sit in a shallow tray with no holes, the insert will hold 32 of these 2.5" pots, keeping them from tipping over in a trays and making quick work of transporting them out to the garden space. The individual seed cup style is very popular for school and community projects as these can go from seed to transplant without needing up-potting in between and come in bright colors and now in clear!
Recommended Plants: Tomatoes, Melons, Cucumbers, Pumpkins, Squash, Peppers and other large-seeded crops
50 Cell Seed Starter Trays
These 50 cell propagation trays are a happy medium of saving you space in your seed starting area while still being able to plant a large number of seedlings like lettuce that will be directly transplanted. Because the 50 cell tray has a much larger soil volume than the 72 cell plug trays or 128 cell trays, you will have a bit more wiggle room when you need to transplant for optimal root growth. Plants grown in these trays will be less likely to become root-bound if unsettled Spring weather delays your planting. This size also allows for canopy development of the seedling.
If you know that your seedlings will need to be potted up before they are ready to move outside, you will want to select one of the cell trays listed below or plan on potting up into larger pots like our new 5 inch grow pots with carrier.
Plastic trays of this size are great for planting early greens and brassica crops like broccoli and collard greens for the home garden. Just be sure that if you choose to mix varieties in one cell tray, they all have similar germination times and time to transplant.
Recommended Plants: Lettuce, brassicas, cucumbers, slow-growing flowers, and herbs.
72 Cell Plug Seedling Trays & 72 Cell Air Prune Trays
The 72 Cell trays are the most popular choice amongst market gardeners. They are a good balance between space for growing and seedlings per tray. Each cell is 1.5" square and 2.25" deep, making them an excellent option for a large variety of plants. These plastic trays are also a good choice for vine plants. However, you will want to transplant the vine plants earlier than you would with the 32 Cell trays to prevent root bound seedlings. This cell plug tray is designed to use a heavy-duty deep tray for easy bottom-watering.
For optimal air pruning and extremely happy plants, we recommend our 72 air prune trays. All the benefits of soil blocking without the mess!
Recommended Plants: Sunflowers, Early Season Peppers, Early Season Vine Crops, Early Season Cole Crops (Cabbage, Cauliflower, Collards, Kale, Mustard, Kohlrabi, Broccoli, Brussels sprout, Watercress)
128 CELL TRAYS
These 128 Cell Trays are a great choice 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 more than a few weeks. Each cell 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 seed starter trays. These 128 seed trays are compatible with the heavy-duty deep tray for bottom watering. You will want to up-pot your seedlings from this size seed tray into a larger pot or grow bag if you do not plan to transplant outdoors for an extended period to prevent seedlings from becoming root-bound.
Recommended Plants: Lettuce, Herbs, Cole Crops (Cabbage, Cauliflower, Collards, Kale, Mustard, Kohlrabi, Broccoli, Brussels sprout, Watercress), Celery, Leeks, Flowers.
200 CELL TRAYS
These 200 Cell Trays are excellent trays if you want to be economical about growing cole crops, lettuces, and other small-seeded crops. You will be able to grow ~2.8 times as many plants with one tray as you would with a 72 cell tray. Each cell is 0.75" square and 2.25" deep.
If you are using a 200 cell plastic trays to start seeds, you will need to transplant your seedlings at an earlier stage. Typically once they have one, at most two sets of true leaves. This plastic tray size is most frequently used by larger-scale farmers and those who intend to pot up their seedlings multiple times before moving outside. They can also be used to start plants going into hydroponic systems if you use a soilless media like coco coir or ProMix.
Recommended Plants: Lettuce and Brassica Crops (Cabbage, Cauliflower, Collards, Kale, Mustard, Kohlrabi, Broccoli, Brussels sprouts, Watercress), Small seeded flowers.
While some experienced farmers have successfully planted crops like beets and turnips in cell seed trays, it is not recommended unless your climate does not allow for the direct seeding of root crops. Carrots, parsnips, turnips, and beets rely heavily on their taproot. This long central root is responsible for much of the water uptake of these plants, and if the root is disturbed or damaged during the transplanting process, the plant will not thrive.
Yes, unlike other root crops, members of the allium family have congregate root structures. This means that they are much more tolerant of root disturbances during transplanting. It is common for growers to plant multiple small seeds per cell and tease them apart for later transplanting.
Starting seeds in cell trays, especially in the larger ones, gives the grower the advantage of being able to start more seedlings in their growing space. This is especially handy for row crops where the grower may want to plant 100 or more of each variety. Growing this many seedling starts in larger seed pots would take up way too much space. The other advantage is that you will waste less growing media starting out your seeds and then up-potting the successfully germinated starts into new pots.
Yes. It is possible to overwater seedlings growing in cell trays. A common mistake growers make is to leave water in the bottom tray at all times. This will eliminate your seedling’s ability to get oxygen. Bottom-watering with a can be properly done by adding just enough water to allow the cell tray to evenly absorb it during the watering and no more. You want to discard the excess water as it will become stagnant and invite anaerobic bacteria to wreak havoc on your newly established seedlings.
Related: Easiest Way to Water Seedlings
Most seedlings can stay in cell trays for at least 4 weeks. The larger the cell volume, the longer a plant can grow before it becomes root-bound. Plants grown in a 200 cell tray will typically need to be potted up or transplanted outside once they have a full set of true leaves. Plants grown in a 32-cell insert pot can be kept in protected conditions for 6-8 weeks. Check out our 3.3" seed starting pots and 5" pots for up-potting starts or shop our seed starting bundles.
If your seedlings have been in the plug tray for too long, they may become root-bound. If this happens, you will see a large number of roots circling the plug when you pull it out of the tray. Plants that have become root bound do not produce new roots easily and will often stay stunted.
The company is the world’s best cheap seed starting trays supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
Transplant shock can also cause your garden plants to be stunted and remain small throughout the growing season. For more on how to avoid transplant shock, check out our Seed Starting 101 Guide for advice on how to harden off your transplants.
If your seedlings become root bound before you have time to plant them, you can improve their chances with a bit of extra work at planting time. Once you have the plug removed from the cell tray, gently tap the bottom of the roots to loosen the soil and use your fingers to tease them apart. It is ok and even desirable to tear a few of the roots when you do this. Separating and tearing the roots will encourage the transplant to produce new side roots and prevent further root circling.
Before we even get into the pros and cons, I just want to get this out of the way: indoor seed starting is not recommended for those brand-new to gardening.
It took me years of gardening before I even attempted to start my own plants indoors. And every year since then, you can bet there have been lessons and learning curves along the way (like that time I added too much of a fish-based fertilizer to a tray and ended up burning all my seedlings).
This is where you might be thinking, Why go through all the trouble of starting your own seeds then? So let's begin by looking at the benefits of starting your own plants indoors by seed.
You might have heard that the variety of the food made available to us at the grocery store has greatly decreased over the past decades. You can expect, for instance, to find only a few different kinds of tomatoes and maybe one kind of cucumber in the produce section, but if you browse a seed catalog, you know there are many more varieties out there.
This also holds true at the plant shop or nursery. The place where you source your plants is a commercial business that would like to stay in business, and because of that, there are only so many varieties they’ll commit to growing for us. If they were to use up resources on some weird heirloom with a flavor far different from what their customers expect, they risk not getting a good return on their investment.
And, hey, we need them to stay in business, so we're thankful for whatever variety they will grow for us.
But when you start your own plants from seed, you have so many varieties to choose from at any time.
The second reason we make the effort to start seeds indoors is timing. Starting your own plants inside gives you a jumpstart on the growing season. You won’t need to start seeds for every plant you want to grow inside, just for those plants that have a very short window during which they need to be planted outdoors and grown to maturity.
Many of us don’t live in places where the temperature, sunlight, and setup are all just right for the plant during the full amount of time it needs outdoors to grow to maturity. Starting plants inside means you can begin growing them early, and then as soon as the weather is ideal, you move them outdoors. Thanks to this head start on the season, you’ll get so much more from the plant because it can now spend more time outside in your garden, growing under its ideal conditions.
The third pro of going through this process is the cost-benefit at scale. If you were to buy a tomato plant at the store, you might spend anywhere from $4 to $15, depending on the maturity of the plant.
Now compare that to a package of seeds. You can buy 15 to 25 tomato seeds for under $4. That means you have the opportunity to grow at least a dozen mature plants for the price of one plant from the store.
This really only benefits you, however, when you do it at scale. Because of the setup required to turn each tiny, affordable seed into a valuable tomato plant the same size as one you’d buy from the store, you should anticipate 15 plants to show for your efforts. Or perhaps ten different varieties of tomatoes to move to the garden. If you’re only after two plants for your garden, you’ll find the expense and the complications of the setup aren’t worth it, monetarily speaking.
When you grow your own plant from seed, you know every little thing that's happened to that plant from start to finish (when it’s moved out to the garden). You know what soil the plant began in and whether it was ever stressed out or overcrowded, because you’re in charge.
You’d obviously hope to buy a quality plant from the nursery. You can even ask good questions like: “How was this plant grown?” or “Were any synthetic fertilizers or fungicides used on this plant?” No matter how much you dig, it’s still hard to know the real quality of that plant—at least until you plant it out in your garden after purchase.
Again, when you grow your own, you can ensure the quality of your plants from the very beginning. That is oftentimes the most desirable reason to start your own plants from seed, especially if growing organically is important to you.
To successfully grow your own seeds indoors, you’ll have to bring elements of the great outdoors inside.
You’ll have to check that air is moving throughout the space evenly and consistently. You’ll have to monitor the temperature, making sure that it’s not too hot or too cold. You’ll have to make sure that your artificial lights are being turned on and off because the sun is not rising and setting regularly inside your home. You’ll also have to monitor the water because, obviously, there won’t be any rain falling from the sky onto your seeds.
Imitating Mother Nature indoors requires extensive setup in order to find consistent success while starting your own seeds. Learn more about the seed starting supplies I recommend.
You’ll need to be able to commit perhaps 15 to 20 minutes a day to tending your seedlings as they begin to grow inside, including monitoring their growth, turning your grow lights on and off, potting them up to bigger sizes, etc.
The biggest time commitment is required when your plants are ready to be hardened off, meaning they’ll need to be transported outside to bask in the sun and then brought back inside every day for at least a seven-day period.
If committing to this kind of time over a period of 45 to 60 days sounds unrealistic or if you’re already struggling to fit gardening into your busy schedule, that just means this upcoming season is not the one for you to start your seeds indoors—and that's okay!
You might start your seeds in just one small tray, but eventually, each of those seedlings in its little cell will need to be upgraded to a bigger pot. Seed starting ultimately consumes more of your indoor and outdoor space than you would have ever expected.
If time or space is limited for you, you can always start really small with just a few plants or hold off for a season or two.
Maybe you just want to feel like gardening is simple and easy. And that’s okay.
The great thing about seed starting is that it’s all up to you. The bad thing about seed starting is that it’s all up to you.
While there are lots of things that can go right thanks to your efforts, there are so many things that can go wrong (e.g., your seedlings can grow mold, you can scorch your seedlings with the grow light, or your baby plants can just fail to thrive). If you’re not ready to take on a new challenge or add a daily habit to your routine, then this is not the right time to take on seed starting indoors.
Save your energy and spend it planning your outdoor garden, cultivating an indoor herb garden, or growing your own microgreens or sprouts. Gardening is meant to be fun, not just practical. If at any point it no longer feels fun, stop putting pressure on yourself to do it this one way this time around. Try again another season.
If you’re ready to commit to seed starting, keep in mind that it takes most gardeners several seasons to master this skill. Give yourself a lot of grace and time to practice, and you’ll get there, too.
The great news is, if you can successfully start your own seeds, then you're moving to an entirely different level of being a gardener. You’ll unlock new and magical parts of gardening, parts that are forever hidden for those who don’t make the effort.
You’ll be able to grow a much wider variety of plants for your garden than you could find at the garden center. You’ll be 100 percent in charge of the types of plants that can go into your garden and when they’re available.
Like I said earlier, it’s all up to you—and that is both scary and amazing. You’re taking all the power, all the excitement, all the possibility of the garden into your own hands.
If you're ready to get started, check out our Seed Starting course inside of Gardenary 365. We've got video lessons to help you learn how to start seeds indoors, including selecting the right supplies for your needs, planting out your seeds, and helping them grow. We'll also help you troubleshoot common seed starting issues.
Thanks for helping make gardening an ordinary part of life again!
Contact us to discuss your requirements of Leak-Proof Seedling Trays. Our experienced sales team can help you identify the options that best suit your needs.