Answers To Your 25 Most Asked Seed Starting Questions
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.
Q1. Where do I buy good quality, organic seeds?
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!
Q2. How do I know when to start each seed?
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.
Use your last frost date as your counting back date as to when it’s safe to transplant out tender seedlings.
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.
You can also follow my monthly seed starting guides if you’re in Zone 2-4.
- 15 Seeds To Start Indoors In January In Zone 3
- 8 Seeds To Start In February In Zone 3
- 20 Seeds To Start In March In The Canadian Prairies
- 50+ Seeds To Start Indoors In April
- What Vegetable & Herb Seeds To Start Indoors In May
Q3. What are the easiest seeds to start indoors?
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.
Overall, seeds that require less growing time indoors can be classified as “easier.”
These are things like squash, pumpkins, basil, marigolds, etc..
Q4. What’s the best seed starting soil mix?
This is one of if not THE most asked question I get! And my answer is a little controversial.
I don’t believe in using traditional, bagged seed starting mixes found at local hardware stores/garden centres.
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 Best Seed Starting Soil Mix Recipe
- 1 part compost or worm castings — I love the Pure Life brand
- 1 part potting soil — ProMix is my go-to
- 1/2 part vermiculite or perlite — a must for good drainage
Q5. Should I soil block or plant in trays?
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.
Q6. Should I wet my soil before planting?
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.
So let me explain!
Your soil will expand as it absorbs moisture.
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.
You want your soil to be damp enough that it sticks together but not soupy.
I wet my soil by mixing it with water in a large bowl before adding to my trays.
Q7. How many seeds do I plant in one cell?
I love this question because the answer is simple!
The smaller the seed, the more you can plant in a single cell.
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.
Q8. How deep should I plant each seed?
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…
The bigger the seed, the deeper it should be planted.
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!
Q9. Do I need grow lights?
If you are indoor seed starting in a Northern climate, the answer is yes — you need grow lights!
There simply isn’t enough natural daylight in the North throughout the Winter months to start seeds indoors.
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.
Q10. Where do I buy grow lights?
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.
Here’s what to look for when purchasing grow lights:
- LED — energy efficient and no fire hazards
- Full Spectrum — closely mimics the sun
- Strips — easier to put on a shelf than the bulkier square ones
- On/Off Switch — easier than always having to plug into an outlet
- Easy to Install — choose ones that come with hooks to hang from a shelf
Q11. Do I need natural light and grow lights?
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.
Q12. How many grow lights do I need?
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.
Q13. How far away from the seedlings should my grow lights be?
The distance between your grow lights and plants is dependant on the stage of growth they’re in.
Here’s how I suggest you adjust your grow lights as your seedlings grow:
- After first sowing your seeds and during germination, hang grow lights 1-2 inches about the soil surface/the humidity dome.
- Once seeds germinate, adjust grow lights to hang 4 inches above top of seedlings.
- As seedlings mature, continue to adjust grow lights to be 6 inches above the top of seedlings.
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.
Q14. How long should I keep my grow lights on for?
Grow lights should be kept on for a minimum of 8-12 hours daily.
Turn on your grow lights first thing in the morning when you wake up and turn them off before you go to bed.
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.
Q15. What temperature do I need for germination?
Indoor seeds will happily germinate at room temperature (20°C/68°F).
Keeping your seed trays in a moderately warm area of your home away from drafts and any forced air heating/vents is ideal.
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).
Q16. Do I need a heat mat and what does it do?
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.
So, do you need a heat mat for seed starting? The answer is no‚ you don’t need a heat mat. But it does help!
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.
Q17. How do you regulate humidity?
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.
In fact, too much humidity will lead to many issues, such as damping off, mold and other air-born diseases.
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.
Q18. Do I need to cover my seedlings?
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.
A humidity dome is ideal for this as it acts like a mini greenhouse, keeping warm air and moisture inside.
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.
Q19. What does “damping off” mean?
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.
So how do you prevent damping off?
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.
Q20. How often do I water my seedlings?
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.
Knowing how often you should water your seedlings requires you to;
1. Check on your plants daily
2. Stick your finger in the soil
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.
Q21. What’s the best way to water seedlings?
The best approach for watering seedlings is to water from the bottom so absorption happens from the roots.
Bottom watering should only start once true leaves emerge. During germination, just gently water by misting with a spray bottle.
I cover how to properly water seedlings in thorough detail in my blog How To Properly Water & Fertilize Your Indoor Seedlings.
Q22. Should I put a fan on my 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.
Q23. Do you need to fertilize seedings?
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.
Q24. When is it time to pot up 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.
When it’s time to pot up depends on the size of the original container your seedling is in.
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.
A good way to check if your seedlings are ready for a bigger home is to remove them from their cell and check the roots.
If their roots are compacted and growing out the bottom of the cell, it’s definitely time to pot up!
Q25. When should I put my seedlings outside?
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!
Tender seedlings should be transplanted outside after your last frost date. Cold-tolerant seedlings can be gradually hardened off outside a few weeks before your last frost date.
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.
And there you have it!
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.
If you have any more questions, leave a comment below! I answer all comments and love hearing from you. You can also follow From Soil to Soul on Instagram & Tik Tok for more organic gardening goodness.