Selecting the Right Seed Starting Cell Trays

WHAT PROPAGATION TRAY IS BEST FOR YOU?

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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?

What size cell tray should I use?

Quickly review some of these seed starting questions.

• Are you growing a large number of one variety of plants for transplanting row crops?

• Are you planting smaller numbers of a wide variety of plants?

• Will you be planting your crops all at once, or will you be using the succession planting method?

• What type of seeds will you be planting? Peppers, tomatoes, lettuce, watermelon, etc.? 

• How large are the seeds?

• How long will your seedlings need to stay in the cell trays?

• Will you be potting up your plant starts or planting out directly from the plug trays?

• How much protected growing space do you have to start seeds in?

• Will you use a heat mat or rely on ambient temperatures for germination?

Quickly review some of these seed starting questions.

Check out How to Size and Use Cell Insert Propagation Trays video for a look at how these trays are commonly used.

Seed Starting Trays Comparison

Tray Type Cells per Tray Cell Size (inches) Recommended Plants 4 Cell Seed Starting Trays 4 2&#;" on top, tapers to 1¼" at the bottom Sweet peas and other crops that need more room, great for up-potting 6 Cell Seed Starting Trays 6 1½" x 1½" x 2&#;" on top, tapers to 1" at the bottom Sunflowers, Early Season Peppers, Early Season Vine Crops, Early Season Cole Crops (modular in 6 packs) 32 Cell Seed Starting Trays 32 2&#; square by 2&#; deep Tomatoes, Melons, Cucumbers, Pumpkins, Squash, Peppers, and other large-seeded crops 50 Cell Seed Starting Trays 50 1¾" x 1¾" Lettuce, Brassicas, Cucumbers, Slow-growing Flowers, and Herbs 72 Cell Plug Seedling Trays 72 1½&#; square by 2¼&#; deep Sunflowers, Early Season Peppers, Early Season Vine Crops, Early Season Cole Crops, Lettuce 72 Cell Air Prune Trays 72 1.37" from the top, 2.29" tall, .87" hole, 1" at the bottom Sunflowers, Early Season Peppers, Early Season Vine Crops, Early Season Cole Crops, Lettuce 128 Cell Trays 128 1&#; square by 2¼&#; deep Lettuce, Herbs, Cole Crops, Celery, Leeks, Flowers 200 Cell Trays 200 ¾&#; square by 2¼&#; deep Lettuce, Brassica Crops, Small-seeded Flowers

What size cell seed trays should I use for a Home Garden?

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.

The Best Cell Plug Tray Size for Large Scale Market Gardens

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. 

Common Questions About Planting in Cell Trays

Can I plant root crops in plug trays?

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. 

Can onions and leeks be planted in seed starting trays?

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.   

What are the advantages to starting seeds in cell trays vs. larger pots?

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. 

Can you overwater seedlings in cell seed trays?

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

How long can my plants stay in the cell tray?

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.

Why are my transplants not growing?

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.

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. 

Can I fix a root-bound seedling or plant?

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. 

Be sure to share your seed starting successes with us on Instagram and tag us with questions you have about the process. 

I've been gardening and writing about gardening for more than 20 years, yet I find I'm always learning new things about the plants, insects and other critters that call my backyard home. That's the great thing about gardening &#; it's never boring! I've worked as a landscaper, on an organic farm, as a research technician in a plant pathology lab and ran a small cut-flower business, all of which inform my garden writing. Someone once asked me when I'll be finished with my gardens, to which I replied, "Never!" For me, gardening is a process, not a goal.

Whether you're new to starting seeds or looking for fresh ways to grow your healthiest plants, we have supplies and systems that ensure success. With so many choices, how do you decide which is right for you? We're here to help.

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.

Factors to Consider

Although you can start seeds in just about any container as long as it has holes for drainage, as with any task you're more likely to have better success using equipment designed specially for that purpose. And if you're new to seed-starting or introducing a friend to growing from seed, why not start with the systems that ensure success? Here are some considerations to help you choose.

• Reusable pots and trays are made from durable materials that can be washed, sanitized, and reused year after year.
• Plantable pots are made from biodegradable materials so the seedlings can be set in the garden pot and all, eliminating root disturbance. Cleanup is easy, and there are no bulky pots to store.
• DIY pots includes those made from recycled materials, such as newspapers, as well as pot-free soil blocks.
• Deep-root pots encourage more extensive and robust root systems that help plants make an easy transition to the garden.
• Self-watering systems deliver water to seedlings as they need it, reducing the risk of over- or under-watering.
• High volume systems allow you to grow a garden's worth of seedlings in a compact space.

Gardener's Best® XL Seed Starting Kit: Deep-Cell Kit Grows Extra-Large Seedlings

This innovative self-watering seed starting system is 30% deeper than our Deep Root, growing full-size, garden-ready seedlings that are hardier and healthier. Optional add-ons, sold separately, include: additional Seed Starting Trays and Humidity Domes for fast germination.

• Self-watering system extends time between waterings
• Durable, reusable & dishwasher-safe
• Large pop-out hole in each cell makes transplanting easier

• Perfect for:

  peppers, zinnias, and other seedlings that would benefit from a BIG starting space; no need to transplant up in a larger pot!

 

Gardener&#;s Best® ECO XL Seed Starting Kit: Deep-Cell Kit Made with 25% Less Plastic

All the benefits of our original XL Seed Starting Kit, but made with hemp fiber and 25% less plastic! Grow extra-large seedlings with an extra-green self-watering seed starting system. Additional Seed Starting Trays and Humidity Domes for fast germination, sold separately.

• Made with hemp fiber and 25% less plastic &#; each kit keeps nearly 3 pounds of CO2 out of the atmosphere!
• Self-watering system extends time between waterings
• Durable, reusable & dishwasher-safe
• Large pop-out hole in each cell makes transplanting easier

• Perfect for:

  peppers, zinnias, and other seedlings that would benefit from a BIG starting space; no need to transplant up in a larger pot!

 

This heavy-duty, recycled-plastic seed starter includes an efficient and effective self-watering system that solves the challenges of over- or under-watering. Simply fill the reservoir and plants get the water they need, when they need it.

• Capilary mat delivers water from reservoir to soil
• Dishwasher-safe for easy sterilization between uses
• Clear cover holds in heat and moisture to maximize seed germination

• Perfect for:

  the brand new gardener. The included humidity dome helps seeds germinate and a bottom-up watering design will support veggies, herbs, and flowers

 

Paper Pots Seed Starter Set: Earth-Friendly Paper Cells

Expandable paper honeycomb creates a whopping 50 cells. When you're ready to transplant into the garden, pots tear apart so you can plant them, paper liner and all.

• Plantable pots are biodegradable and minimize transplant shock
• Ideal for high-volume growing
• Reusable perforated tray; paper cell refills available

• Perfect for:

  cucumbers, sunflowers, and other seedlings that don&#;t like being handled due to transplant shock

 

Paper Pot Maker: Make an Endless Supply of Plantable Pots

The ultimate in upcycling! In seconds you can transform strips of newspaper into seed-starting pots, ready to nestle into a waterproof tray and fill with soil mix. Easy, fun, and economical for high-volume growing.

• Biodegradable pots minimize transplant shock
• Make as few or as many as you need
• Eliminates the clutter and storage hassles of plastic pots

• Perfect for:

  radishes and other quick-growing seeds that don't need to spend weeks in a seedling-sized pot

 

Biodegradable Pots and Tray: Plantable Pots Minimize Transplant Shock

These fully biodegradable pots ease transplanting woes and work, allowing you to plant directly into the garden &#; pot and all. The wood fibers immediately begin to biodegrade, ensuring adequate moisture and aeration as well as restriction-free root growth.

• Plantable pots transplant directly into the soil
• Heavy-duty plastic tray is reusable year after year
• Suitable for organic gardening! No binders or glue in the pots.
• Additional biodegradable seed trays sold separately

• Perfect for:

  cucumbers, nasturtium, squash, and other seedlings that grow quickly and do not appreciate having their roots disturbed

 

Cowpots: Plastic-Free Pots with Fertilizer Built In

An ingenious farmer makes these transplanting pots from odor-free, 100% composted cow manure. As your seedlings grow, the pots gradually degrade, releasing organic nutrients. Plant pot and all in the garden for healthy root growth without transplant shock.

• Biodegradable pots transplant directly into garden
• Roots grow through and take natural fertilizer with them
• Eliminates transplant shock

• Perfect for:

  heavy feeders&#; like tomatoes, squash, and broccoli will appreciate the slow release of nutrients as this manure-based pot degrades.

 

Soil Blocker: Make Perfectly Sized "Pots" with No Waste

Never run out of starter pots again! This clever device presses moistened soil into compact blocks with a small divot in the top, ready for dropping in a seed. Roots grow freely, get oxygenated, and grow more robustly as a result.

• Make blocks as you need them &#; no need to store plastic pots
• An easy, no-waste, DIY solution that's perfect for high-volume growing
• Minimizes transplant shock.

• Perfect for:

  peppers, tomatoes, and other seeds that would benefit from a BIG starting space; no need to plant up in a larger pot!

 

Galvanized Seed Starter: Stylish Design and Smart Features

An attractive seed starter worthy of display on a tabletop or under lights. The leakproof tray holds 24 individual, tapered cells, so you can bring the ready-to-transplant seedlings to the garden without disturbing the other plants.

• Longlasting and resuable, year after year
• Chic galvanized metal complements home decor
• Seedlings remove easily with little root disturbance

• Perfect for:

  starting a variety of seed types; separate pots make it easy to transplant individual plants one at a time 

   

 

Deep Root Seed Starter: Grow Bigger, Healthier Plants

This self-watering system features deep growing cells that result in more root mass &#; the secret to vigorous seedlings that thrive when transplanted. The smart design is inspired by the systems used in European horticulture laboratories.

• Heavy-duty system can be reused for many years
• Self-watering system ensures proper hydration

• Perfect for:

  peppers, tomatoes, zinnias, and other seeds that would benefit from a BIG starting space with plenty of root space

 

Pop-Out Pots: Seedlings Grow 40% Larger with No Transplant Shock

Pop-Out Pots are the secret to seedlings that are primed for robust growth in the garden. Transplant young seedlings from seed starting trays into these self-watering pots. When it&#;s time to set plants in the garden, simply lift the fabric strips to &#;pop out&#; plants without disturbing roots.

• Self-watering system ensures perfect hydration
• Easy-lift line minimizes root disturbance
• Compact design fits on a windowsill

• Perfect for:

  cucumbers, squash, sunflowers, and other seedlings that don&#;t like being handled due to transplant shock

 

Self-Watering Galvanized Seed Starting Tray: Galvanized Individual-Cell Seed Tray Has Self-Watering Convenience

We designed this system for season after season of successful seed-starting. The leak proof tray holds 24 individual cells, so you can bring the ready-to-transplant seedlings to the garden without disturbing seedlings that aren't quite big enough.

• Enjoy seed-starting success year after year
• Tapered pots let you easily remove seedlings
• Wire grid with moisture-retaining mat keeps seedlings hydrated

• Perfect for:

  starting a variety of seed types; separate pots make it easy to transplant individual plants one at a time

 

Sili Seedlings Seedling Tray, 6-Cell: Eco-Friendly, Silicone Seed-Starting System is Reusable

These sustainable silicone seed-starting trays are durable, reusable, and easy on tender young roots. Because they're so flexible, you can pop seedlings out with ease &#; no tugging or tearing required.

• Pop seedlings out quickly and easily
• BPA-free, food-grade silicone
• Dishwasher safe

• Perfect for:

  starting seeds with kids (crush-proof!) or gardening in colder climates (frost-proof!)

 

Sili Seedlings Seedling Tray, 10-Cell: Silicone Seed-Starting Trays Are Dishwasher Safe

These silicone trays make seed-starting so much more fun! Like other systems they have base drainage so that soil doesn't stay soggy and rot your seeds. Unlike plastic trays, they won't snap, crack, or break from use. Plus, they're flexible and twistable &#; so when seedlings are big enough to go out to the garden, it's super easy to pop them out. Use 5 to a base tray and you have 50 plants in a 10" x 20" space!

• Durable and flexible
• Reduces risk of transplant shock
• 5 trays fit perfectly in our Heavy Duty planting tray

• Perfect for:

  starting A LOT of seeds with kids (crush-proof!) or gardening in colder climates (frost-proof!)

 

Coco Coir Seed Starting Discs and Tray: No-Mess Seed-Starting System with 50 Plantable Coir Discs

You'll love this reusable, no-mess seed-starting system. Just hydrate the 50 individual coir discs in their cells, add your seeds, and wait for the little shoots to appear! Water as needed until they're ready to transplant into the garden, coir and all! Replacement coir discs available separately.

• No soil to mix or scoop
• Start a lot of seeds in a small space

• Perfect for:

  s

  tarting a whole garden; 50 pre-fi

  lled cells make it easy to start many, many seeds at once

   

Whether you&#;re a seed starting beginner or a long-time grower experiencing new challenges, you&#;re not alone! We&#;ve collected some of the most common questions we get asked about seed starting with helpful answers and troubleshooting advice.

Finding the right seed starting system is only half the battle! Explore our deep dive on seed-starting to learn the ins and outs of growing flowers and veggies from seed, so you can graduate from novice sower to master grower!

Are you interested in learning more about cheap seed starting trays? Contact us today to secure an expert consultation!