I finally bought reusable seed starting trays to replace the flimsy black plastic ones that crack apart after a single season. The new seed starting trays are silicon, can be sanitized in the dishwasher, and come with humidity domes and built in mini grow lights.
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The cost is pretty affordable as well, coming out to about $0.50 cents per plant. I plan to use these for the next 10 years or more, which means they would come out to about $0.05 cents instead!
Jump to:I bought these colorful silicon seed starting trays this year - both for fun and function. They sit adorably in the window, making me smile every time I walk by. As a bonus - they are as practical as they are cute.
Update : sadly, the company no longer makes this product. I found something similar on Amazon, so you can try these instead, which look to be very similar (but less colorful).
Silicon seed starting trays have recently started popping up and are gaining popularity over the standard paper-thin black plastic trays you find at nurseries. Those plastic trays crack after one use and can get a bit toasty on a seedling heat mat.
The silicon trays are flexible, making it easy to push on the bottom to pop the plant out for transplanting. They can also be placed in the dishwasher for easy sanitizing year after year.
I bought the 8-pack of silicon trays that each come with a thick plastic bottom, and a tall 4" humidity dome with mini grow lights built in. It also comes with 80 plant tags and a couple mini plastic tools for punching holes in soil or scooping soil. Each tray has 9 cells for a total of 72 cells.
I took measurements of the seed starting trays in case you are trying to fit them on a windowsill, a standard tray size, or trying to determine what to use for your seed starting medium.
The 8-pack of silicon trays comes with 4 USB "double" cables to power the grow lights. Each cable splits into 2 cords and each of those cords is 14" long. I bought a $15 USB power strip from Amazon to plug them in.
Everything you need for seed starting is listed at the bottom of this post, in one place.
In my experience, the most important factor for successful seed starting is finding the right soil or growing medium. This can make germination easy or near impossible, depending on what you choose. The two easiest seed starting options are Horticubes and OrganiPlugs. Seed starting soil mixes are also a good option.
Seeds need to stay moist in order to germinate. It might seem like you can simply pick any soil and keep it watered, but too much water without drying out invites mold. Mold can stunt or kill the seedlings.
Seed starting soil mixes are formulated to hold moisture, often including perlite or peat, which is a good thing! But I've found soil to be too finicky for seed germination for my liking. It seems too easy to underwater, resulting in poor germination, but overwatering often leads to mold growth on the top. I know other people who have had more luck with soil mixes or soil blocking.
This year I'm trying out OrganiPlugs and they've worked out well so far. They are made of peat and coco coir and feel quite spongy. They stay moist and so far I haven't run into mold problems (and don't expect to).
OrganiPlugs are made to fit into standard seed starting trays. They fit almost perfectly in each cell of the silicon trays I bought - they have just a little bit of wiggle room.
I'm also using Horticubes for herbs this year. They don't fit in the silicon trays, instead they are meant to sit in a large tray then get transplanted shortly after germination.
(All of the products are also listed at the bottom of this post in one place).
I have a couple other options to suggest if for some reason you don't want to share in the joy of these cute, resusable trays!
Empty yogurt, fruit cup, or applesauce containers make great seed starting pots - just be sure to drill a few holes in the bottom. Leftover take-out containers work well as a tray to collect the draining water.
When upcycling containers, you'll likely need to use a seed starting soil mix. If you do this, be sure to check the moisture levels several times a day so it doesn't dry out, or stay too wet.
OrganiPlug offers a 50-cell tray pre-filled with their OrganiPlugs. It doesn't get much easier than that. However, the tray will likely only be usable for 1-2 years as the thin plastic will crack as you remove the plants for transplanting.
I actually use this seed starting method every year, including this year - Horticubes. They are the most reliable and easiest seed germinating medium. I really can't stress how easy these are to use.
These feel like foam but are made from biodegradable materials that will continuously break down over the course of the year. It's sterile medium so it won't transfer pests or diseases.
Horticubes hold water extremely well and don't mold. Seed germination is easy and all but guaranteed. I never run into problems when using Horticubes.
The downside is they are very small and offer no nutrients. That's fine for germination but they will need to be transplanted to larger containers as soon as their first set to true leaves shows up. If you don't transplant, they just stop growing (I know, because I've done it!)
I use these every year for starting herb seeds where I want a bunch of each type of plant. Once they sprout, I transplant them to a larger tray with soil that I continue to water. When they are ready to be transplanted outdoors, I break apart the roots if they've grown together and set them in their sunny spots!
One note worth mentioning is the sheets that arrive are fragile. They can easily break apart if you aren't careful or if shipping was rough.
Get Horticubes on Amazon or Harris Seeds for a similar price.
There are a few other options to consider - rockwool, foam plugs, and seed starting soil mixes. I don't think these options are as good as the ones listed above, however.
Rockwool is made from molten rock that is spun into threads to create the product. I used rockwool cubes a while back but stopped when I learned it might be harmful to the lungs.
It's too bad because they are a fantastic medium. They are relatively cheap ($0.10 per cube or less), hold water extremely well, and never mold. Seed germination in these is outstanding.
Some people still use them, and I don't feel like I've found enough credible evidence to confidently advise against using these. I personally don't use them because I prefer to err on the side of caution, and I've found other alternatives.
Foam plugs are another option. They actually work quite well - they hold water, don't mold, and are affordable. But I personally don't use them because they don't compost into the soil, leaving little spongy plugs around.
Seed starting soils are formulated specifically for seed starting. They often contain perlite, peat, and coco coir to hold water. As I mentioned earlier though, I always have trouble with either over watering and getting mold problems, or underwatering, resulting in poor germination.
If you've had luck with seed starting soils in the past, then I see no reason you wouldn't continue to have success. It's a good, affordable option!
Amazon is actually a great place for seed starting supplies. I find their prices are often much lower than online seed websites and even hardware stores. The links in this article are affiliate links, which means I get a small commission if you make a purchase (and a big thanks if you do!). In return, I only recommend products that I personally use and feel good recommending.
Everything you need for seed starting with my silicon tray setup:
Alternatives
Extras:
Seeds need warmth to germinate, so most people set them on a little heat mat. Once they germinate, remove them from the heat mat and leave them at room temperature.
The heat mats get slightly warmer than room temperature, and the inexpensive ones don't have controls other than being plugged in or not. Mine are all like this and were very inexpensive (small ones are around $15). This 10x20" heat mat will fit the 8 silicon trays (they might hang off the edges a little). I don't have this one in particular because I bought mine over 10 years ago. It has good reviews and looks exactly the same as what I use.
Alternatively, set your seeds on top of your fridge to germinate. It's just warm enough to lend a helping hand instead of a heat mat.
I bought seeds from a dozen vendors last year. In part it was to evaluate vendors since so many people ask me for my favorite sources. But part of it was chasing unique varieties that only one or two vendors sold.
I share a dozen of the best places to buy seeds, from incredibly cheap sources for $2 or less, to fully organic but more expensive. I also have a good source that specializes in each specific climate, including the Pacific Northwest, West Coast, Southwest, Southeast, Midwest, and Northeast.
For information on how to start your seeds, Swanson Nursery has a good tutorial.
4-pocket binder sheets fit seed packets perfectly. The smallest pack you can buy seems to be 25-30, which gives you 100-120 pockets. When storing them back-to-back (one faces front, one faces back), you get double the storage for 200-240 seed packets. I bought a 50-pack and it was way too many - oops.
I also bought a 1.5" thick binder which was definitely too small. I would definitely recommend a 3" ring binder, especially if you are storing large seeds like beans, peas, and corn.
I often get the same Instagram DMs asking recurring questions about seed starting. And so I thought, why not put my answers to all those questions here in a blog for you! These are the answers to your 25 most asked seed starting questions. I’ve also included links throughout to my other blogs that cover some of these seed starting specifics in more detail.
This post may contain affiliate links to products for your convenience. From Soil to Soul gains a small commission from purchases made through those links, at no additional cost to you.
There’s many amazing seed suppliers across Canada & the U.S. that I buy from each year. But my go-to supplier is West Coast Seeds .
I find their germination rates are superior to others. Plus they work with a network of farmers to source their seeds, so they have an awesome selection available.
For more suppliers, check out my post Where To Buy The Best Organic Vegetable Seeds In Canada.
Your local garden centre should also carry their preferred line of seeds. Just be sure to look for a certified organic brand if that is of importance to you, which it totally should be!
When you should start your seeds is totally dependant on your grow zone and last frost date. These are two terms you should become very familiar with!
Both of which I explain more in my Ultimate Seed Starting Guide For Canadian Gardeners.
For quick reference, you can use Canada’s Plant Hardiness Zones map (or the USDA Hardiness Zones Map if you’re in the U.S.) to see what zone your general region is considered. Here in southern-MB/Winnipeg area I’m in a Zone 3b.
I also love this tool by The Farmer’s Almanac, which helps you find your average last frost date for your area by simply entering your postal code/zip code.
For example, here in my Zone 3 garden, my last average frost date is typically May 27. So if a seed needs to be started 5-6 weeks before my last frost, I would start them indoors in early April.
Oh, the question of ease. It always comes up and the truth is — seed starting does take some work regardless of what you’re growing.
So if you’re heading into seed starting with the expectation that it will be a hands off process, think again! It takes time, patience and consistency to grow anything.
With that being said, there’s definitely some seeds that are easier to start than others. You can find my full lists of the easiest herbs, veggies and flowers to start indoors in my post The Ultimate Seed Starting Guide For Canadian Gardeners.
These are things like squash, pumpkins, basil, marigolds, etc..
This is one of if not THE most asked question I get! And my answer is a little controversial.
Why?
Because while bagged seed starting mix is light and fluffy, which is great for baby seeds germinating, it contains zero nutrients for your plants. This means you’ll have to fertilize and amend your seedling soil much earlier and more often.
So instead, I make my own seed starting soil mix.
The choice is yours! And there’s no right or wrong choice.
In recent years, soil blocking has become really popular and for good reason! You don’t need to invest in any plastic trays. Your soil blocker tool basically compresses the soil tightly enough that it maintains its shape and acts as the container.
I personally have not yet gotten into soil blocking, mostly because I have an abundance of trays in my greenhouse that I figure I might as well use. I do also like how easy it is to move around seedlings to different shelves/under different grow lights when using trays.
100% yes! Yes, yes, yes.
I recently shared a Tik Tok seed starting some brassicas and was surprised by how many comments I received asking why I wet the soil.
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So let me explain!
If you wait to water until after you’ve planted your seeds, you’ll run into issues with seeds being pushed to the surface or you’ll find you haven’t filled your cells with enough soil.
Plus if you’re soil blocking, you absolutely have to wet the soil ahead of time to ensure it sticks together.
The other main reason for wetting soil before planting is to help with germination since seeds require moisture, light and oxygen to germinate properly.
I wet my soil by mixing it with water in a large bowl before adding to my trays.
I love this question because the answer is simple!
For example, these eucalyptus seeds pictured are incredibly fine and small. So I sow several in a cell and then divide them to their own containers once they’ve matured to a few inches tall.
Whereas a slightly larger seed like a cabbage, tomato or pepper seed (pictured below) can easily go into its own cell.
However even with smaller seeds, you can always keep 1 seed to 1 cell. This works perfectly fine too.
This is another really common question I often get asked. And because I can’t cover the thousands of different seeds, I’ll instead say this…
For tiny, fine seeds it’s often best to barely cover with soil. Instead you’ll just sprinkle on the soil’s surface, mist with water and let them germinate.
On the other hand, really large seeds like beans should be planted a couple inches deep.
When in doubt, consult the back of your seed packet, which should provide seed planting depth instructions. This is actually another reason why I love West Coast Seeds — each seed pack has a tiny ruler on the back for reference!
If you are indoor seed starting in a Northern climate, the answer is yes — you need grow lights!
I know for some this isn’t the ideal answer because grow lights can be intimidating at first and a bit of a cost investment. But trust me, they will ensure you have success with your seed starting.
Grow lights mimic the temperature & strength of the sun in July, which is ideal for plants. So as you can see, natural daylight alone wouldn’t be able to do that.
You can likely purchase grow lights at your local garden centre or online at retailers like Amazon.
My preferred grow light brand is Sunblaster. They’re really high quality and won’t cost you an arm and a leg, price range is about $55-$150 CDN.
Great question! The answer is no.
Having both natural day light and grow lights is great but not necessary.
If you have grow lights, they’ll do all the hard work for you.
We start all our seeds in our basement where there are windows but they don’t provide a ton of light.
This is dependant on how many trays of seeds you’re planning to start.
If you’re brand new to seed starting, invest in 1-2 grow lights to start. If you purchase a 42″ long grow light, you can easily fit 4+ trays under it.
The other thing I often get asked is whether you should have two grow lights to cover each tray. Ideally, yes. But is it necessary, no.
In fact I only have one grow light to cover each shelf. I simply turn my trays every other day to ensure all seedlings are getting enough light and it works just fine.
The distance between your grow lights and plants is dependant on the stage of growth they’re in.
The goal is to avoid the grow lights being too close and burning the top of your seedlings while also ensuring they’re not too far away, causing your seedlings to reach for them and get lanky.
Grow lights should be kept on for a minimum of 8-12 hours daily.
Simply put — your grow lights should mimic the pattern of the sun in July.
Grow lights should NOT be kept on 24 hours. Plants need a period of darkness too and actually do significant growing during their dark phase.
Indoor seeds will happily germinate at room temperature (20°C/68°F).
Definitely avoid trying to germinate seeds in a cooler environment like a garage.
However, with a bit more warmth and humidity, germination will speed up significantly. This doesn’t necessarily mean you need any additional “tools” to have success, but they do help (as you’ll see in the next questions).
A seedling heat mat is a mat with an embedded heated wire inside. Your tray of sow’d seeds sits on top of it and it provides bottom warmth to the roots of your plants.
Seedling heat mats help with faster germination and stronger root development because they keep the soil evenly warm.
To put things into perspective, I start hundreds of seedlings annually and only have 1 heat mat! I use it only for my trickier seeds (like eucalyptus) and then transfer it to other trays as needed.
I really like this heat mat from West Coast Seeds because the thermostat is outside the mat so the temperature adjusts automatically based on the air temperature. Pretty cool!
But you can find a plethora of other heat mat brands on Amazon as well.
Gardeners tend to be really concerned with humidity and often ask me about this. But honestly, my advice is not to worry about it too much!
It’s much more important for your seedlings to have adequate air flow and ventilation than for you to create a super humid environment.
So instead, focus on keeping your seedlings in an area of your home that is a consistent temperature and away from any drafts or forced air from radiators/vents.
You don’t need to cover your seedlings but you do need to cover your soil during germination. Confused? Don’t be! Let me explain.
During the germination process, it’s key to keep your soil moist and the soil temperature nice and warm.
I really like these vented humidity domes from West Coast Seeds because you can let a little bit of air in as germination begins.
But once your seedlings have germinated and begin to put on their true leaves, you’ll want to remove the humidity dome to avoid damping off.
Damping off is when your seedlings suddenly collapse and die. One day your seedlings seem great and the next, they’re dead. Sad, I know! But it’s easy to avoid.
Damping off is ultimately a disease that happens when there’s too much moisture/dampness in and around your seedlings. This can be due to lack of air flow and/or overwatering.
First, water carefully and consistently (more info on watering below!).
Next, avoid letting your seedlings sit in standing water.
And finally, be sure to provide them lots of air flow and ventilation.
This is the golden question! And one I find many gardeners get stressed out over. But don’t worry, there’s no exact science to watering seedlings nor does there need to be.
The most important thing is to be consistent with your watering while also ensuring your seedlings are not sitting in water.
During germination, soil should remain consistently damp (another reason why planting into wet soil is key!).
Then as seedlings are growing, water every other day or so. To know exactly how often to water, stick your finger 1/2 inch deep into the cell. If it’s dry, the roots need water. The top of your cells may look dry from the grow lights but as long as your roots have moisture your plants are good.
The best approach for watering seedlings is to water from the bottom so absorption happens from the roots.
I cover how to properly water seedlings in thorough detail in my blog How To Properly Water & Fertilize Your Indoor Seedlings.
Yes! You should definitely put a small fan on your seedlings. Air flow is really important. And there’s numerous benefits.
A steady breeze on your plants helps develop strong stems while also keeping away air born diseases, fungus and mold.
You don’t need to go out and invest in a massive fan. You actually don’t want to as it will be too much power for your tiny seedlings.
Instead try a small, clip-on, electric fan like this one.
Yes! You should organically fertilize your seedlings about once a month or so.
Wait to fertilize until your seedlings have put on their second set of leaves and are 3+ inches tall. Opt for a liquid fertilizer as opposed to granular as it will be much gentler on your plant. I love the Sea Magic Kelp-Based Fertilizer.
For more detailed fertilizing info, check out my post How To Properly Water & Fertilize Your Indoor Seedlings.
Potting up seedlings is the process of moving your plants into a larger growing space so they can continue to develop roots and get bigger.
If your seedlings are in a tiny cell from a seed starting tray (typically no more than 1 inch deep), you’ll want to pot them up once their second set of leaves has matured. This can be anywhere from 2 weeks to 2 months depending on what you’re growing.
If their roots are compacted and growing out the bottom of the cell, it’s definitely time to pot up!
Transplanting seedlings outdoors is so exciting as it means you can finally free up some space inside your home and officially start the gardening season!
The hardening off process is extremely important and should not be skipped! Otherwise your seedlings will get transplant shock and all that hard work will go to waste.
Those are the 25 most frequently asked seed starting questions answered. Phew!
I hope you learned something from this blog and can head into your seed starting with confidence.
Want more information on Leak-Proof Seedling Trays? Feel free to contact us.