Seed starting trays are a convenient and compact way to grow flower, vegetable, and plant seedlings before placing them in your outdoor garden or potted planters.
But not all seeding trays are the same, and buying the wrong size or type can ruin your gardening dreams before they can begin.
To help you avoid disappointment when starting seeds, learn all you need to know in this guide to seed starting trays, including:
- Reviews of the best seed trays
- If seed starting trays are necessary
- What features and accessories to look for before purchasing
- Answers to common questions about using seed trays
Seed-starting trays can streamline your gardening game and jump-start your spring garden so let’s dig right in!
- Best Seed Starter Trays For Seedlings
- Seed Starting Tray Buying Guide
- Seed Starting Tray FAQs
- In Summary
Best Seed Starter Trays For Seedlings
Seed Starting Tray Buying Guide
Before you rush to the garden center or online to order seed starting trays, please take a few minutes to learn more about whether or not you need them, what materials they come in, and what other accessories or options for starting seeds are available.
Don’t waste money on gardening products you don’t need or won’t work like you expect them to. It’s best to always make an informed purchasing decision to grow your gardening equipment collection.
Do You Need A Seed Starting Tray?
You don’t need seed starting trays to grow seedlings, but they sure do make it easier.
Using a mishmash of various containers to start seeds takes up a lot more space than starter trays that can hold neat rows of perfectly sized seedlings for transplant.
Trying to evenly water or heat the soil of different seeding containers is difficult, while compact trays filled with seeding cells are fast and simple.
Drainage holes at the bottom of seed starting trays also help maintain a better soil moisture level, so more seeds germinate.
Some trays have a specific shape to hold peat pellets. Many gardeners like how simple it is to start seeds using pellets as shown in this video:
Lastly, using seed starting trays makes it simple to move whole groups of plants at once instead of individually seeded pots.
Whether you need to move them outdoors for hardening off, or under grow lights once they sprout, you can quickly move 50 or more plants at one time.
Seed Starting Tray Materials And Construction
Most seed starting trays are plastic and can be reusable or throw-away.
Some trays are biodegradable, which eliminates the need to remove plants from the cell before transplanting. You stick the whole cell into the ground, and eventually, the material disintegrates, and the roots spread out into the ground.
Are plastic seed starting trays better than biodegradable trays?
Both work well to grow seedlings, but which you choose to use depends on several factors.
Over time, it’ll cost less to purchase reusable seed starting trays if you start plants every growing season. Do be aware that the thicker material in reusable cells makes it more difficult to get the seedlings out for transplant.
You also need to clean the trays and have space to store them until next season.
Organic gardeners or vegetable growers should look for BPA-free polypropylene plastic seed trays or other safe plastic that won’t leach chemicals into the soil.
Throw-away plastic trays are inexpensive and very thin, making it easier to manipulate the seedlings from the tray.
While you can carefully clean and reuse this type of seed starting tray, you’ll most likely toss them out and need to buy more next year. The expense may not bother you, but the plastic waste heading to the landfill might.
Biodegradable trays cost more, but they save a lot of time during transplant and are environmentally-friendly. Not having to pull plants from the cells avoids damage to the stems and roots when you repot or place them in the ground.
Additional Options And Accessories To Consider
Look for these helpful accessories with your seed starting tray or purchase them separately for best germination results:
- DOME – A clear plastic cover over your seeds will help maintain the ideal humidity level which increases germination time and success
- BASE TRAY – A durable base tray keeps cell trays organized and allows you to water plants from the bottom to reduce disease and pest issues
- WATERING MAT – A special mat that draws water to the cells without oversaturating the soil
- HEATING MAT – Most seed starting tray kits will not come with a heating mat, but they do increase germination and growth rates and are a great accessory for early indoor growing
Seed Starting Tray FAQs
How Long Can Seedlings Stay In Trays?
To answer this question, I’ll assume you’ll want to know how long seedlings can stay in the tray’s cells before roots get restricted, and plant growth stagnates.
The length of time a plant can stay in the tray depends on the size of the cells, and if you plan to directly transplant into your garden or repot into a larger container first.
Here is a quick breakdown of how long you can expect to safely leave seedlings in multi-cell trays:
- 12-cell: 10-12 weeks
- 18-cell: 8-10 weeks
- 24-cell: 6-8 weeks
- 36-cell: 5-7 weeks
- 48-cell: 4-5 weeks
- 60-cell: 3-4 weeks
- 72-cell: 2-3 weeks
- 128-cell: 1-2 weeks or until two real leaves form
A standard size planting tray is 10″ x 20″ and holds the seeding cell inserts so you can swap out different sizes according to your needs.
Remember that you’ll need more space in your greenhouse or growing room to accommodate more trays if you use 12 or 24-cell inserts over starting seeds in a 128-cell flat.
Anytime you see roots growing through a jiffy pellet or a coir pot seed tray, you’ll have to transplant them into the ground or a larger pot.
How Do You Get Seedlings Out Of Trays?
The best way to get seedlings out of tray cells is to turn them over in your hand and gently push or tap on the bottom to help the soil and roots slide out in one piece.
To make this process easier, I always cut up large seeding cells into smaller sections before planting and setting them in the tray.
Trying to tip over and remove a solid 48-cell tray will be nearly impossible without damaging the seedlings. Luckily, you can purchase seeding tray cell inserts already cut down into smaller sections.
Never grab the seedling by the stem and pull upward, as you can break the stem more often than get the plant, roots, and dirt safely out of the cell.
If roots seem bound to the cell tray, slide a butter knife or popsicle stick gently down around all the edges to loosen the rootball, tip the cell over, and try again.
What Temperature Will Kill Seedlings?
Seedlings are more delicate than mature plants, so temperatures both too high or low can kill them.
Most mature plants can survive unless temperatures go below 28°F for at least five hours, but seedlings can die at temps in the 32-33°F range.
Avoiding cold snaps is one reason gardeners prefer to start seeds indoors, so seedlings have a better survival chance.
On the high side, seedlings will begin to falter at temperatures above 90°F, but death is less likely unless the soil dries out.
So while you may need to warm up soil for seeds to germinate, the seedlings don’t need the ambient air temperature to be as high for healthy growth.
Warm temperatures cause seedlings to quickly grow tall and leggy, which stresses the plant leading to weak growth.
The best temperature to keep seedlings is between 60-65°F. Plants will grow a bit slower at this temperature, but it encourages stocky stems, thick foliage, and a healthier planet.
Now you know more about seed starting trays and how beneficial they can be to increase germination rates and expand your garden neatly and more efficiently.
For those on a budget, the Solight 4-Pack for pellets is an excellent value for the number of plants you can start, is reusable, and the technique is more simple over messy soil.
For those who want the best overall seed starting kit, I suggest the Burpee Self-watering Seed Starting System that gives you every component you need so you can immediately start seeds with one purchase.
Using seed-starting trays is an easy way to manage your early garden planting. Better yet, starting seeds costs much less than buying plants from the garden center so that you can create the lush garden of your dreams no matter how tight your budget!