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I think we can all agree options are good- but give us too many options to choose from and we can easily feel overwhelmed. And as a result we may find ourselves failing to make any sort of decision at all…
This is at least how I felt when I was just getting started growing flowers and was trying to decide on which seed starting trays to purchase.
I mean, no one wants to spend money only to find out later that they invested in the “wrong” trays…am I right?!
And so today, I’m hoping to put your mind at ease. In this blog, specifically- I thought we’d discuss the pro’s and con’s to some of the different seed trays out there on the market. I’m also going to share with you some of my favorite trays to use; and even give you some considerations to think about when you’re selecting your own trays.
So if you’re wanting to learn more- let’s go!
(Psst.. Want to skip the explanation and get right to the good stuff?! I got you covered, this tray is my absolute favorite for starting seeds; and truth be told, it’s the one tray I use most on my small flower farm)
Understanding Seed Trays:
Now in general, all seed trays serve the same sort of purpose- they hold your soil in place so that you can grow healthy transplants for your flower garden.
By planting your seeds in a single tray, it makes it easier to treat your seedlings all the same as they’re in the same container. You can water the entire tray at once. You can transport your seedlings at once- you know, when it’s time to plant you just have to handle a single tray and bring it out to the garden with you.
For the most part, all of the seed trays that you will encounter, they have the same overall length and width. And they can typically all fit inside a standard bottom watering tray.
The biggest difference among trays is really found with the number of cells they contain.
The Importance of Cell Size in Seed Starting Trays:
Cell counts vary widely in trays and you can commonly find trays that have 32-cells, 50, 72, all the way up to 128, 288 and beyond.
Now, the more cells in a single tray- the smaller each individual cell will be. So for example, the cells of a 50 cell tray will be larger than those in this 72 cell tray.
Choosing which cell count to use is based partly on preference and how much room you have available to seed start. And then it’s based partly on the needs of the seeds you’re growing.
You see, the size of a cell limits the growth of a seedling. Smaller cells leave less space for seedlings to grow.
Ideally we want to give the seedling as much room as it needs to expand its roots and put on top growth so that it really thrives before we put it out in our garden.
During the growing process, if your seedling runs out of room to grow, generally, what happens is that the seedling becomes root bound. When this happens, the roots of your seedling become so entangled that they have a hard time absorbing nutrients from the soil.
Now some seedlings can bounce back after becoming root bound but it’s better if we can prevent this altogether as root bound plants can experience stunted growth, delayed flowering, or in extreme conditions, they can just flat out not survive.
Understand that the purpose of seed starting is to produce a robust plant start. So giving our seedling the proper amount of room to grow is important.
Like I said, in an ideal situation we’d give our plants as much room as possible. But for a lot of us who grow seedlings on any kind of scale, the problem is that we often don’t have unlimited space.
I have a number of wired shelves where I grow all my plant starts. The shelves are 4 feet wide and so on one shelf I can fit 4 trays.
If I’m growing my seedlings in 32 cell trays that means one shelf can hold a grand total of 128 seedlings. You know, 4 trays times 32 cells.
Now compare that to if I were growing my seedlings in 72 cell trays. Suddenly that same amount of real estate on my wire shelf is enough to grow 288 seedlings- more than doubling the amount of seedlings I’m able to grow in the same amount of space.
Can you see how it’s a fine balance between maximizing the space you have available so that you can grow as many seedlings as possible with also doing what’s best for the health of your seedling?
Best Seed Tray Recommendation for Flower Farmers:
For me, the 72 cell tray (with a few exceptions) is sort of the compromise between these two factors that I just mentioned. The reason that I often encourage new growers to start with the 72 cell tray is that for most flower varieties, the 72 cell is sufficient space for a seed to grow into a large and bulky enough plant start without requiring you to repot it before it’s time to to transplant into the garden.
And if I’m being really specific, my absolute favorite seed starting tray is the 72 cell seed tray that comes from Bootstrap Farmer. I believe that I’ve shared in past YouTube videos how I stumbled across the Bootstrap Farmer brand- but 5 seasons into growing flowers, I can honestly say that I haven’t found a tray that compares in strength and quality to this tray.
Even full of soil the Bootstrap Farmer trays don’t buckle- they’re a really durable tray and for me, it’s worth it to spend the extra dollar or two per tray because I know that I won’t need to replace them near as often.
So let’s discuss some instances when I would choose to use a different tray.
Seed Starting Trays for Specific Circumstances:
128-Cell (and smaller) Seed Starting Tray
If you’re struggling with germination with some of your seeds- tools like heat mats and humidity domes can be useful in helping you achieve those ideal situations for your seeds to germinate.
While I look at my equipment as a necessary investment in my business- sometimes you just don’t have the extra money to spend so that every tray has its own heat mat and humidity dome.
And so one of the ways around this may be to use a smaller-cell tray to start with. A 128 cell tray is great because you can start a good number of seeds in a small space- and this single tray fits nicely on heat mat.
In my experience, you just have to be careful that you’re monitoring your 128 and smaller cell trays to make sure that they have enough space for your seedlings to grow until they’re ready for transplant. You may find that you’ll need to bump up your seedlings into a larger tray so that they can continue to grow until it’s time to plant them outside.
50-Cell Seed Starting Tray
Speaking of more room, if there’s one flower variety I definitely recommend you give plenty of room to it’s sweet peas. Sweet peas are known for their large root system and for that reason I always use a 50 cell tray when starting my sweet pea seeds.
In recent years, I’ve actually switched to using these 50 cell extra deep trays for my sweet peas as it allows for more root development.
We actually use these deep 50 cell trays for an increasing number of our crops- we start our ranunculus and anemone corms in these and I even pot up my paperwhites bulbs in these trays
All of these varieties that I just mentioned are flowers that can benefit from a little extra space for their roots.
Now before you go crazy and grow all sorts of flowers in these extra deep trays- I will caution you, in my experience these trays are little more difficult when it comes to regulating moisture. Personally I feel like these trays don’t wick up moisture from their bottom drain holes as well and so I often find myself overhead watering when I’m using these trays verses bottom watering. And I just find it a little more difficult to actually gauge the amount of moisture at the very bottom of these deep cells.
I think it’s much easier to maintain a consistent amount of moisture in any of these other more standard trays that are just 2 to 3 inches deep.
20 Row Channel Tray
This next tray that I want to share with you is a little unique- it’s a 20 row channel tray. This is something I’d recommend if you are someone that hates sowing small seeds.
We all know the struggle that comes when you’re trying to sow something like snapdragons or herbs like oregano- the seeds are just so tiny it can be difficult to even decipher what’s a seed vs just a speck of dirt. I’ll admit, some seasons I have the patience to sit at my seed starting station I’ll use a moist toothpick to pick up each individual seed and put it into its own individual cell within my cell tray.
But other seasons, I find myself in a hurry or I just don’t want to bother with the especially tiny seeds. And in these instances, I will pull out my channel trays.
The purpose of this tray is that you’ll fill each channel with soil, you’ll indent your soil to create a small “channel” for seeds to be poured into. Unlike a cell tray where you’re placing one seed into each cell. With this tray you’re simply pouring seeds the length of your channel. Usually a single one-hundred seed packet is enough for one channel. As you can imagine this is a huge timesaver for getting seeds started.
Now I’ll treat my channel tray like any other seed tray- and I can fill more channels if I’d like- but I’ll usually put this on a heat mat and place a humidity dome over time. Once the seeds have germinated and my seedlings have put on just a little growth- I’ll pop these out of their channel and pot them up in my favorite 72-cell trays where they’ll continue to grow until I’ll plant them out in my garden.
For a lot of people, having to handle these baby seedlings is much easier than having to deal with the eye strain that can come from trying to separate tiny seeds into individual cells.
A channel tray is a two-step process instead of just one like when you’re seeding directly into a cell tray- so you may have to do a little trial-and-error to see if this process works for you, but it is a great work around especially if you’re someone that struggles with planting small seeds.
I’ll also use a channel tray if I have a flower variety that doesn’t have great germination. By planting lots of seeds in a single channel and then only bumping up the seeds that actually germinated I can avoid those instances where I have trays that have lots of empty spaces because the seeds I planted there simply didn’t germinate.
Seed Trays We’re Trialing this Year:
Now the last tray that I want to share with you today is a new tray that I’m trialing this season. And I’m honestly pretty excited about these.
So far in this post, I’ve shared with you the different types of trays that I use for my own seed starting practice. Realize however, that there is another method of seed starting that eliminates the need for any sort of tray at all.
This practice is what we call soil-blocking. Instead of planting your seeds into soil held in place by a tray, you plant your seed into a cube of soil.
There’s some great benefits to soil blocking- the biggest one being that it prevents your seedlings from becoming root bound.
In a cell tray, when your seedling’s roots hit the side of the cell, they’re forced to grow downward in a spiral, and left in the tray too long they’ll often circle the bottom of the cell becoming root-bound as they tangle together.
Soil blocking, however, avoids this problem. When your seedling’s roots reach the outer edge of the soil block and actually come in contact with the outside air, they experience what we call “air-pruning”. What this means is that root- it dries out and stops outward growth and signals secondary root development within the soil block. Overall you get a more developed, fuller root system for your seedling.
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Despite these amazing benefits, I just don’t have the patience myself to plant my seeds into soil blocks- it can sometimes be a finicky process and I just much prefer the convenience of seed trays.
Air prune trays are sort of a hybrid method of seed starting that allows you to experience the benefits of soil blocking because the trays are designed in such a way that your seedlings can air prune themselves- but they have the added convenience of a tray.
I’ll be curious to see if my seedlings that grow in this tray are in fact healthier than those grown in my more standard trays. For this season, I’ve only purchased a handful of these air pruned trays so that I could get a feel for how they perform for me.
My plan is to use them on flower varieties that are particularly sensitive to root disturbance. My thoughts are that if I can grow a more robust root system on those sort of plants, they’ll likely transplant into my garden much more smoothly and overall perform better as they’ll have less chance of transplant shock – that’s at least my theory.
I will say that these trays are an investment. Still, they are incredibly well-made trays so I have no doubt that I’ll be able to use them for many seasons and in that sense, I’m not worrying about getting my money’s worth out of them.
But I’ll definitely keep you updated on how these perform for me as the season progresses.
Conclusion:
So there you have it- an inside peek into the different seed trays that I use in a season. I hope this blog post gives you some things to consider when you’re deciding on which trays you’d like to use in growing your own flower starts.
Be sure to let me know in the comments below what you decide on as I’m always curious as to what other growers use!
Growing a basic understanding of seed starting fundamentals can truly take your skills to the next level. Ready for true seed to harvest growing? You can do it, have a lot of fun and impress your family and friends. If you’re brand new to gardening, however, I’d suggest you wait a year or two before diving into starting seeds inside. There is some complexity to it and you’re better off sowing seeds outside and using nursery transplants to gain quick success. When you’re ready to dive in on starting your own seeds, this little guide is a great place to start.
Featuring my FREE downloadable custom seed starting plan
These high-level principles of seed starting will give you the confidence to get started and the tools to be successful. Starting seeds can really save you some money and let you grow unique plants not widely available in nurseries. You can grow all sorts of things inside with a few simple tools and a little time investment. There is nothing quite as rewarding as watching those little seedlings emerge, grow and later move them to the garden. This subject is broad and a little further reading may be needed, but here are a few basics to keep in mind as you get started.
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Seeds
Starting can save money and add variety for your annual flowers, herbs and vegetables. Perennials from seed take quite a bit more skill, so stick with annuals for now. Options include annual flowers, broccoli, cucumber, kale, lettuces, peppers and tomatoes. Basil is one of the easiest herbs to start from seed indoors. Crops like beans, beets, carrots, onion, peas, spinach and radish will do best sowed directly outside.
Have you fallen for the big lie that seeds expire after one season? Not true. That printed expiration date on the seed packets is a good way to sell more seeds. It really has nothing to do with their viability. Most seeds, if kept dry and sheltered from light, will remain viable for three to five years, in my experience. I may sow my seeds a bit more heavily in years three to five, but I honestly don’t think about it much. I sort through my seeds every few years and toss any older than five. If you’re really into being precise about it, you can test your seeds for germination. It isn’t difficult. There is a great deal more online about this topic.
Don’t forget that seed packets have a wealth of information. I encourage you to read the back of every seed packet you acquire and use it as an ongoing reference.
Grow lights
Many people ask me if they can start seeds in a sunny window. Yes you can, but not very well. Conditions can’t be controlled and there simply isn’t enough light, regardless of how sunny that window is. Further, you’d spend a great deal of personal energy moving your trays around to grab that ideal light. You’ll find a lot more success by investing in some grow lights.
Two 40-watt bulbs in a standard fluorescent shop fixture would provide enough light to grow seedlings indoors, but I strongly encourage investing in LED grow lights. They are more expensive on the front end but their advantages are many. LED grow lights are more efficient, last longer and cost significantly less to operate than fluorescent options. Additionally, unlike fluorescents, they are non-toxic and mercury-free. I love these adjustable rope hangers made especially for hanging grow lights. Once you’ve caught the seed starting bug, you might consider treating yourself to this LED grow light system like I use at my house.
Lights should be no more than 4 to 6 inches above the seedlings. You will need the ability to change the light height as the seedlings grow. Light systems are available in store or online to aid in this effort. Lights should be on 12 to 14 hours a day. A timer is helpful to ensure proper lighting. The seedlings need to sleep just like we do!
Peat Pellets & Trays
Something to grow your seeds in is essential. My favorite seeding solution is peat pellets. They can’t be beat for easy seed starting. As their name implies, they are quite literally small, rounded, compressed masses of dried peat moss. Peat moss is responsibly sourced sphagnum moss grown and harvested in peat bogs throughout Canada. It can be hard for new gardeners to comprehend growing plants in a soilless medium. It’s actually incredibly effective and most seed starting is done in a soilless mix. Peat is unique in that it can hold 20X its weight in water, provides perfect aeration for roots and help retain the nutrients plants need.
I use 50mm size peat pellets for my seed starting to allow my plants to grow longer and stronger in the peat pellet before I transplant them to a larger peat pot. Smaller size peat pellets are either 36 or 42mm in size and are great for starting herbs or flower seeds, however in my experience, those types of plants do just fine in my 50mm pellets. To hold my pellets, I use this reusable greenhouse kit every year, adding new pellets to the trays each year. Peat pellet packages come with instructions on starting your seeds, but honestly it is just as easy as soaking your pellets with water, letting them grow into a nifty little pot, pulling back the opening and planting your seeds. They already have fertilizer incorporated so you have everything you need to grow your seed successfully except the water and light which you provide.
Other seed tray options
Many varieties of seed trays are available online or at your local nursery.
You can also use no-cost solutions like saved produce containers, milk cartons, paper cups or egg cartons to start your seeds. For any container, it is important that there are drainage holes in the bottom. Follow the directions on the seed packets for planting depth and don’t forget to label your seeded cells so you know what’s in your tray. These plant tags and marker do the trick.
It is common, and usually necessary, to transplant your seedlings at least once to a slightly larger container for a few more weeks of growing inside. For transplanting, I like to use peat pots. The advantage of peat pots is that you can plant these right into the garden without removing the plant from the pot. In fact, you’ll very likely have roots coming right through your pot when ready to plant. I usually tear the bottom of the pot a bit when I plant them into the garden to allow the roots to easily reach deep. The rest of the pot remains intact, completely planted into the ground. The pot will decompose naturally, limiting the stress on the seedling.
Growing medium
If you’re wanting to use traditional seed starting trays or recycled planting containers instead of a peat pellet system, you’ll need a soilless growing medium. Fancy phrase for dirt? Not quite. Seeds started indoors need a lightweight, clean, soilless seed-starting mix.
Warmth
Most seeds require a consistent 70 to 75 degrees to germinate. I use a water-resistant heat mat made for this underneath my seed trays to ensure they stay warm and cozy.
Air flow
In addition to these essentials, once I uncover my seedlings, I keep a fan gently circulating the air around my seed starting area. I find the circulation improves my seedlings success.
Water
Germinating seeds need daily attention, consistent water and good drainage. An empty water bottle with holes poked in the lid with a pin makes the perfect mini waterer that seedlings love.
Clean
Wash any containers and tools in soapy water and disinfect them in a solution of 9 parts water to 1 part bleach before you begin. Keep your workspaces and supplies clean throughout your growing season.
When
Having a crop specific plan that you can customize to your location and conditions is essential for seed starting success. The right timing is important so your seedlings are ready and well prepared to go into the garden at exactly the right time.
These plans utilize the last average frost date in calculations. This date is May 10 in my hometown of Cedar Rapids, Iowa, for example. Google your town’s last average frost date. I’m not kidding, try it and the info will pop right up. What did we ever do before having Google at our fingertips?
Once you know your last frost date, you’re ready to use my FREE downloadable Seed Starting Plan. Follow the guide and you’ll have a custom plan specifically tailored for your conditions. I created my own years ago and keep it in a gardening journal, adding notes and learnings throughout the years.
Moving into the garden
A few days of gradual acclimation to the outside in a protected area, a process known as “hardening off”, followed by planting in the garden, with close attention to moisture, will maximize your chances for a successful transition. There are various methods to this. You might use a cold frame, watching the forecast closely and adjusting temps in your frame by propping open or closing the lid as needed. I recommend closing the lid on a cold frame at night when used in early spring when temps are falling into the 40s. In a less equipment needed method, you can also harden off your seedlings by putting them outside in an area away from winds and other harsh conditions and bringing them back inside at night or when a cold spell sets in.
Easy seed storage
If you’ve dabbled in seed starting, or just fallen for the end-of-season clearance seed packet sale, you know how quickly your seed treasures can become a tangled pile of packet disorganization. Fear not, this quick and easy seed storage hack will have your future green babies back in order in no time.
Grab a hardware storage container at your local home improvement store. The one featured here is 20 inches wide by 16 inches tall by 6.5 inches deep with drawers that are 4.5 inches wide by 5.5 inches deep. This size just happens to hold most seed packets perfectly. Grab a hardware storage container at your local home improvement store. The one featured here is 20 inches wide by 16 inches tall by 6.5 inches deep with drawers that are 4.5 inches wide by 5.5 inches deep. This size just happens to hold most seed packets perfectly.
Use a label maker and refill tape to label your drawers. You can screw your seed storage to a wall, but I like to set mine on top of a workbench in my basement seed starting area where I can move it or add more storage as needed. I’ve been using this super cheap method of seed keeping for years and can’t imagine trying to organize my seeds without it. The extra drawers come in handy to store other small-scale garden essentials.
You’re going to be tempted to install your cool new seed storage solution in your garage or shed. Don’t do it! I thought this was a great idea, too. That fall, I worked really hard to install my seed storage in my garden shed. Little did I know that all winter long, mice had taken up residence and were dining on a buffet of my carefully organized seeds. Imagine the carnage before me when I opened the door! Drawers were in various stages of open, closed or thrown on the floor with seeds – and more seeds – everywhere! The beautiful packets were shredded or gone all together. Take my warning seriously and choose a cool, critter-free area out of direct sunlight, ideally in your home.
Keep those seeds dry
Your seeds aren’t going to fare very well if they aren’t kept dry. You know to choose a cool, dry spot, but did you know there’s more you can do? Have you ever wondered what those little cylinders that come in your prescription pill bottles are all about? Those plastic bottles contain a food-grade desiccant, or drying agent. These little guys take on any excess moisture to keep your pills dry, or in the case of this cheap trick, your seeds. That’s right, pop one of these in each of your spiffy new seed storage drawers and you’ll keep any humidity or invisible moisture out of your seeds.
Whether you’re new to growing veggies or just new to dabbling in seed starting, don’t be afraid to dive in! There is so much satisfaction when you see your first baby seedlings poke their heads out. As your seedlings grow and move ultimately from seed to harvest, you can say – I grew that!
For more information, please visit Leak-Proof Seedling Trays.
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