Pocket trays come in all kinds of sizes, from 10 cells, 32, 48, 72, even 128, but what does that actually mean?
Simple answer: the number of “pockets” is the number of seedlings you can start at once, and the cell size determines how long those seedlings can stay there before they need more room.
It all comes down to space: how much root room your seedling needs to grow before it’s ready to move up.
How to choose the right tray
Ask yourself one question:
Am I starting big, fast-growing plants… or tiny, slow growers?
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Bigger seedlings (sunflowers, squash, cucumbers) need bigger cells sooner
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Tiny seedlings (lettuce, herbs, flowers) can start well in smaller cells because they don’t need as much root space right away
Quick guide: what to grow in each tray size
10 pockets (largest cells)
Best for big starts or plants you want to hold longer before potting up:
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Sweet peas
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Sunflowers
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Early-season peppers
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Early-season vine crops
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Early-season cole crops
(Example product: 1001 Insert Tray – 10 cells)
32 pockets (large cells)
Best for larger-seeded crops and seedlings that grow quickly:
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Tomatoes
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Melons
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Cucumbers
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Pumpkins
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Squash
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Peppers
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Other large-seeded crops
(Example product: 804 Insert Tray – 32 cells)
48 pockets (medium cells)
A great “middle ground” tray—roomy enough for many crops without taking over your setup:
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Lettuce
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Brassicas
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Cucumbers
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Slow-growing flowers
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Herbs
(Example product: 806 Insert Tray – 48 cells)
72 pockets (smaller cells)
Best when you want to start a lot of seedlings and pot up later if needed:
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Sunflowers
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Early-season peppers
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Early-season vine crops
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Early-season cole crops
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Lettuce
(Example product: 72 Cell Plug Tray)
128 pockets (smallest cells)
Best for tiny seeds and crops that transplant well—great for starting big quantities:
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Lettuce
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Herbs
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Cole crops
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Celery
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Leeks
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Flowers
(Example product: 128 Cell Plug Tray)
When do you transplant into nursery pots?
This is the second most common question, and the answer is:
Pot up (transplant) when you see:
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2–3 sets of true leaves (not the first “baby” leaves)
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Roots wrapping around the bottom or coming out drainage holes
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The seedling is drying out fast (needs water daily)
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Growth is stalling even with good light and warmth
Can you leave them in the tray?
Yes… for a while. Trays are perfect for the early stage, but keeping seedlings in small cells too long can cause:
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Root binding
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Slower growth
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Less vigorous plants later
If outdoor planting is still weeks away, it’s usually better to pot up once than let seedlings struggle in a tiny cell.
A simple rule to remember
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Small cells (72–128): great for starting, but plan to pot up sooner
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Larger cells (10–32): seedlings can stay longer before needing a nursery pot
Need help choosing trays, domes, or nursery pots?
Pop in and we’ll help you match the right tray size to what you’re growing, so your seedlings stay strong from day one.
Shop seed-starting trays, domes, and nursery pots here: https://www.ritchiefeed.com
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