15 Myths About Seeds and Seed Germination

Robert Pavlis

Starting plants from seed is a great hobby and a good way to increase your collection of plants. Most people only think about germinating vegetable seeds and much of the information on the internet is focused on these. But there is a whole other world out there. I am always surprised when people don’t understand that all of the perennials, trees and shrubs originally come from seed.

There is still a lot of mystery around seeds and for many species we still do not understand the best way to germinate them. This allows amateurs and hobbyists to do their own thing. This is great because it adds to the collective knowledge, but it also leads to many myths about starting plants from seed.

Sanguinaria seedlings Myths About Seeds and Seed Germination
Myths About Seeds and Seed Germination, picture of Sanguinaria canadensis by BotantyCa

Days to Maturity

Days to maturity is also called days to harvest, and this value can be found on the package of many vegetable seeds. One would think that this is the time it takes to eat the food after planting the seed, but it is not that simple.

For seeds that are usually planted directly in the ground, like carrots and peas, days to maturity are what you expect; the number of days it takes to produce food after planting the seed.

Plant Science for Gardeners by Robert Pavlis

But for seed that is normally planted indoors, like tomatoes, it is the time needed to produce food after transplanting.

The other myth about days to maturity deals with the accuracy of the number. We all live in different climates that change from year to year and yet all of the packages have the same number. How can it be correct for all of us? It can’t.

The number is only a guide for telling you when you will be able to eat. It is best used to compare one cultivar to another, of the same type of plant. Beefsteak tomatoes mature in 96 days and Sweet 100s mature in 60 days. You can expect to harvest Sweet 100 before Beefsteak.

To better understand days to maturity have a look at Days To Maturity – What Does It Mean?

YouTube video

Double Dormancy

peony grown from seed
Peony grown from seed – does double dormancy exist?

If you plant some peony or trillium seed in the fall you won’t see any green growth until the second spring – if you’re lucky. This is routinely described as an example of double dormancy – the seed needs two cold periods before they germinate.

It may take trillium and peony seed two years to show green above the ground, but whether or not this is double dormancy depends on your definition of germination. If germination is defined as the point when a radicle emerges from the seed, then neither plant has double dormancy.

In both trillium and peony, the seed germinates the first spring, but only makes a root. A shoot and leaves show above ground in the second year.

Building Natural Ponds book, by Robert Pavlis

In fact many of the seeds that are reported to have double dormancy, don’t exhibit it. You can read more about this here; Double Dormancy in Seed – Does it Exist?

Wash Pots in a 10% Bleach Solution

Should you wash pots before reusing them? It certainly seems to make sense. Why risk the chance of disease spreading from last years plants to this years seeds? Like so many things that make sense, this one is mostly a waste of time.

Plant specific diseases are not likely to be a problem since home gardeners are always planting something different the following year. Seedlings are also unlikely to get plant specific diseases – they tend to occur once the plant is outside and growing for a while.

There are some common generic diseases like damping off disease that affect most seedlings. The problem with these fungal diseases is that the spores are everywhere. Even if you use brand new pots you still have a chance of getting this disease. Your cultural conditions are more important than the cleanliness of the pot.

Granted, it makes good sense for commercial operations to be extra cautious because a disease outbreak can be costly, but for the home owner growing a few seeds each year, there is little benefit to washing recycled pots.

Stratify Seed in the Fridge

Stratification is a process where the seed is given a cold treatment to get it out of dormancy. Many people simply put the seed in the fridge thinking that this is stratification – it’s not. Stratification does not occur in dry seed. The seed needs to absorb water and then receive a cold treatment.

In a few cases, seed does require dry stratification, but in that case, the instructions will specifically mention the ‘dry’ part.

A good way to stratify seed in the fridge is with the baggy method.

YouTube video

Use Full Spectrum Lights to Grow Seedlings

Full spectrum lights will work, but they are not required for starting seeds. Any kind of cheaper cool or warm florescent light will work just fine. The key is to keep the plants very close to the bulbs, 2-4 inches, so they get as much light as possible. Try to use a fixture with 4 bulbs in it. Keep the light on for 12-16 hours. Our electricity costs are less at night, so I run mine overnight to save money and use electricity at a time when there is excess in the system.

Windows almost never provide enough light to grow seedlings properly, and they rarely provide the right temperatures. Days can get very hot, and nights are usually too cold.

Starting Seeds in Eggs

seedlings in eggshellsStarting seeds in eggs is very popular on social media. It’s OK for something fun to do with kids, but it’s a dumb idea for the serious gardener. There is not enough soil in an egg to get any type of root system going, and if you leave the egg on when you plant outside, as usually recommended, the roots have no way to get out of the egg.

Other small systems like egg cartons and yogurt cups have similar problems. Seedlings need space – give it to them.

Germination Requires Warm Temperatures

I see this statement a lot and it is just not correct. Granted many people who say this are only trying to germinate common vegetable seeds and most of them benefit from warmth during germination, but not all. Many seeds will germinate in the fridge, and some even need to be cold in order to form leaves. The peony is like this. It germinates warm producing a radicle (root), but then it needs a cool period before it will initiate stem and leaf development.

Many seeds need a cold-warm-cold cycle, and others need a warm-cold-warm cycle.

seedling heat mat
Seed heating mat

So lets say the seed in question is a warm germinator and you want to provide some extra heat. A common suggestion is to use a special heating mat made for seed germination. Does this really work?

The heating mat certainly provides heat, but how much? Many manufacturers don’t even tell you how much heat you get, but some do, and they say “heat mats keep soil at a constant 10° to 20°F (6° to 11°C) above room temperature“.

In winter Canadian homes set their thermostat around 20°C (68°F). If the heating pad raises this by 9°C, the temperature of the soil would be 29°C (84°F).

Most warm germinating seeds, germinate between 18° to 24°C (65° to 75°F), well below the temperature produced by heating pads. Granted, more expensive units have a thermostat control, but most hobby units don’t. As temperatures go above the optimum range, germination rates decrease.

Why pay extra for hydro and the mat when home temperatures are already in the optimum range? One reason might be that it allows you to germinate seed in the basement which could be cooler than normal room temperatures.

Lets look at some common vegetable seed.

Lettuce Seed

Lettuce seed will germinate as low as 4°C (40°F), but it will stop germinating above 27°C (80°F). Best germination is at 21°C (70°F) or normal room temperature. A heating mat, in the average home, can prevent germination.

Tomato Seed

Tomato seed germinates best between 21° to 27°C (70° to 80°F). Germination is poor below 10°C (50°F) and above 35°C (95°F). Some warmth may be beneficial, but they will germinate just fine at room temperatures.

More Temperature Considerations

If temperatures are a bit on the low side, germination will take a bit longer. Tomato seeds will germinate in 4 days at optimum temperature and in 7 days at lower temperatures. The three extra days are not usually important for home gardeners. I just set mine on my desk and wait.

A lot of people suggest that you can put the seed on top of the fridge where it is a bit warmer. This was true many years ago, but fridges are now designed so that the top does not get warm.

Once the seed germinates and you see a half inch seedling, the temperature should be reduced to a range between 16° to 21°C (60° to 70°F). The heating mat should only be used for germination, not for growing the seedling.

Start Seeds On Top of the Fridge

Old fridges were made so that they produced heat at the top of the fridge. This made them a nice warm place to germinate seed.

Many years ago the technology was changed so that heat is now produced at the back of the fridge, and many direct it out the bottom to dry up any collected moisture.

Even when fridges are enclosed in cupboards, the top stays at room temperature. I actually measured mine to be sure. So there is no reason to start seeds on top of modern day fridges.

Sterile Seed-Starting Mix

If the growing medium is too wet or not sterile, disease can strike.” This is common advice but it is not true for the simple reason that there is no such thing as sterile potting mix.

Using packaged seed-starting soil is a good idea and in some cases this has been heat treated. But even if the package says it is sterile, it’s not. Which is OK, since you don’t need sterile soil. The most common disease of seedlings is damping off and it is a fungus that is in the air or on your hands It will find your plants no matter which soil you use.

For more on sterile soil see Sterile Soil – Does it Really Exist?

Jiffy Peat PelletsJiffy-7 pellets

Jiffy peat pellets are commonly recommended for starting seeds. They come as compressed disks, that expand with water. You place your seed on top and the pellet becomes both the soil and pot.

These are not a good system for several reasons.

  • Dry out too fast
  • Too small for most plants
  • The mesh does not decompose

Jiffy Peat Pellets – Not Good For The Environment

Water From Below

I found statements like this; “Never water the seed-starting mix from the top; that courts disease (especially a fungus disease called “damping off”).” Instead you should set the pots of seeds or seedlings in a tray of water and let the water soak up from the bottom.

There are some advantages to watering from below.

  • Less compaction of soil
  • No disturbance of newly germinated seeds
  • No damage to small seedlings
  • It may wet the soil more evenly

But there are also some disadvantages.

  • More work if you have lots of pots
  • Watering from above washes seeds into soil, ensuring good contact
  • In hard water it brings salts to the surface of the soil as water evaporates

Does watering from above cause diseases? I could not find anything to support or dispute this claim. Seedlings should be grown with plenty of air movement, so getting water on them should not be a problem – the moving air will quickly dry them out, especially in a home.

Soil will not be wetter with either watering option, provided it drains well.

I doubt that watering from above causes diseases, and it is the method used by most commercial operations.

On a personal note, I water newly planted seeds or seedlings from the bottom, to make sure the soil is properly wet. Until seeds germinate, I prefer bottom watering so seeds are not disturbed too much, but the ones being started in pots outside, get watering from above. Once germinated, all pots are watered from above.

Cinnamon Prevents Damping Off

Many home owners use cinnamon to prevent damping off. They generally sprinkle the cinnamon onto the soil or newly germinated seedlings.

Cinnamon has been shown to have anti-fungal properties but I was not able to find any studies that support the use of cinnamon sprinkled onto seedlings to prevent damping off. You can read the full story here; Cinnamon – Does it Stop Damping-off in Seedlings?

Non-GMO Seed

Many commercial packages of seed, destined for the home gardener, is now labeled as Non-GMO. Many consumers that are not regular readers of this blog, perceive this as a good thing. After all, they mistakenly believe GMO seed will produce food that is harmful.

There are no GMO seeds available to consumers. So there is no point in labeling seed packages as Non-GMO. It is just marketing.

I understand that you can now get some GMO seed in smaller amounts, like a pound, but that is not something the home gardener will ever buy and it is limited to things like corn.

It would be nice if seed producers were more honest with their customers, but I can’t blame them for labeling their seed as non-GMO. If some do it, they all need to do it to stay competitive. And consumers are demanding such useless labeling.

Safe Seed Pledge

In 1999 the Council for Responsible Genetics started the Safe Seed Pledge “to connect non-GM seed sellers, distributors and traders to the growing market of concerned gardeners and agricultural consumers. The Pledge allows businesses and individuals to declare that they “do not knowingly buy, sell or trade genetically engineered seeds,” thus assuring consumers of their commitment.”

Over 100 seed companies have now signed onto this program, many of which are organic seed companies which are not be allowed to sell GMO seed anyway.

Since GMO seeds are not available to the consumer, this program means nothing. What a waste of time.

Certified Non-GMO Seeds

I have seen this term used by some consumers and by a couple of seed companies. But there seems to be no such thing.

Maybe consumers are mixing up certified organic seed? A few seed companies also promote the fact that they are Non-GMO Product Verified but that is something different.

I don’t think there is such a thing as certified non-GMO seed.

Learn More About Germinating Native North American Seed

If you want to learn more about germinating native North American seed, have a look at BotanyCa – a great place to buy seeds and a great place to learn a lot about germinating them.

Don’t know how to germinate a specific seed? My favorite source for such information is the Germination Guide at the Ontario Rock Garden & Hardy Plant Society website.

References:

1) Main image source; BotancyCa

2) Seedlings in Eggshell image source; Scholastic

3) Seedling heat mat image source; AliExpress

 

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Robert Pavlis

I have been gardening my whole life and have a science background. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

18 thoughts on “15 Myths About Seeds and Seed Germination”

  1. I’ve been starting seeds and growing plants for over 50 years and have NEVER used heat mats (with one exception that I’ll get to that is outside the “normal” practices you are talking about). I got into it on a growing forum once with a woman who very arrogantly asserted in a very long post that lettuce seed starts best with significant bottom heat – even provided her with links to three separate well-regarded universities that had published information and tables on the subject of germination success rates at different temps for lettuce and other common garden plants. The heat she was recommending would have guaranteed between 0% and 10% germination LOL! I was surprised by the number of people who insisted that the references I provided didn’t matter and I was being “mean” to someone who was “just trying to help”. This was about 10 years ago and I guess that attitude is at the base of the anti-vax movement that has resulted in over 750,000 deaths so far in a pandemic that isn’t going to abate until people GET THE FREAKING VACCINATION!

    The thing is that your grow lights – if you have enough of them – provide plenty of heat in a normally heated home for any of our common garden vegetables that might need a bit of extra heat, say, eggplant which is typically recommended to be germinated at higher temps because it is a tropical perennial (also peppers). But if you have enough light on them they will germinate just fine, the lights provide any extra heat they need. You need to worry more about heat DISSIPATION (or at least I do, given the size of my setup).

    My sole exception is when I start curry leaf plant from seed. Those DO germinate far better and far faster with significant bottom heat. But that’s not exactly a common garden plant, is it? LOL! They will still germinate without it but it takes way way WAY longer and I would expect a concomitant increase in failure rate (no data to back that up but curry leaf seed (not the fruit, the seed) has to be planted while still green, absolutely fresh, so I surmise that at least some of it might rot before it germinates without bottom heat).

    The first time I did this I gave up on the unsprouted seeds to early and removed the trays from the bottom heat with about 2/3rds germination, only to find that the rest of the seeds still sprouted later on (they were in 72 cell paks), it just took them longer. I had greater than 100% germination. Well not really – curry leaf plant throws little baby clones and every seed sprouted and then a lot of them threw out between 1 and 3 clones as well.

    My dad had a seed starting setup in the basement where he mounted fluorescent lights using a pulley system for each rack of lights, per shelf. The entire light assembly on a shelf moved up or down evenly as one unit just by pulling on one cord. I wish I knew how to do that. I haven’t been able to find anything online for how to design something like that. It was an elegant system as well as eminently practical. Nope. I just have to count chain links and fumble around when I move my lights, LOL!

    Reply
  2. This is a wonderful post. Could you please tell me what fruits and vegetables to avoid having in the fridge during stratification? I’ve heard certain fruits and vegetables can release gases that prevent proper germination after stratification is complete. Is this true?

    Reply
  3. Are there any myths about seed starting soils? I want to start tomato seeds and I had bought jiffy and realized that it isn’t good after the fact 😑, so what do I do now? What kind of soil should I use for starting seeds that is also good for transplanting into a container? I live in an apartment (if that’s relevant info).

    Reply
  4. Hi, thank you for posting this. I am curious about stratifying peach or other stone fruit pits. I’ve run across different blogs or YouTube videos, some say put in fridge, others say you must open the pit, but I usually damage the seed when I do that. I have tried putting pits in a container of soil for a couple months but got bupkis. I will try your baggy method next. Is a wet paper towel enough for a stone pit? And do I need to split open the pit?
    Thank you,
    Daniell

    Reply
    • When in doubt, I run several parallel tests at one time. Do some with a whole seed and others with open seed.

      Paper towel will work for larger seeds, but to be honest, I prefer doing large seeds with peat moss in baggies. I think it keeps the seeds a bit wetter.

      Reply
  5. Aside from the precautions mentioned above, starting seeds in eggshells does not work at all in areas of low humidity, ie desert gardening, or in dry houses. Just like using toilet paper tubes, in areas of low humidity the tube, or eggshell has to be packed into wetter soil, so why not just use the soil? By the time for transplanting comes around you’ll have to transplant all the soil around the eggshell anyway.

    Reply
  6. Hi Mr Pavlis, what evidence is there to support the practice of burying fish as fertilizer? Is it something the Native Americans really did, and does it do any good?

    Also it is rather silly that people try to avoid GMO seeds when many crops we eat are probably GM (papaya, corn, squash, etc). And nature has been genetically modifying plants for thousands of years. Cabbage, lettuce, cauliflower, and kale came from the same inedible plant.

    Great post as always. Your post about eggshells in particular was shocking and changed the way we gardened.

    Reply
    • I do not know if Native American actually planted fish with crops. I tried to find a reference for that, but didn’t find any.

      Fish is organic matter, and all organic matter contains nutrients. So when they compost in the soil they will release the nutrients.

      Reply
  7. Thank you for having this site … I frequently pass this URL on to other gardeners and love it when you write “no studies found” or “I don’t know” or you personally test a theory, rarities in today’s age of quick misinformation and yesterday’s “garden lore.” Love it! May your seeds germinate abundantly, your plants be vigorous, and your weeds be few!

    Reply
  8. Congratulations on those sanguniaria Robert.
    Glad to hear we are in agreement over not washing pots and trays although I think even you might be horrified at how dirty my pots are!

    Reply
  9. Excellent article! I find sprouting seeds very exciting, and sometimes very disappointing, and it’s good to sort through all the advice. A couple things popped into mind:

    There is one advantage to “sterile” potting soil: if I’m not familiar with the seed being sprouted, at least there won’t be any weed seeds coming up. I have grown weeds in pots by mistake, when reusing old soil…

    Regarding heating mats, I’d read that even soil, being moist, will remain cooler than room temperature, due to surface evaporation. This should be easy to experiment with, maybe comparing the temperature of a cup of wet sand versus a cup of dry sand?

    And regarding native plants, I’ve had no luck planting Asclepias incarnata and Asclepias tuberosa, any advice? I wonder if the slugs are getting them.

    Reply
    • I grew incarnata two years ago, ’twas very slow to start. I think that they sat for about a month without germinating until I moved out from under the artificial lights, perhaps because it was too warm, so you should try that!

      Reply
  10. Excellent post Robert, as usual. I especially liked the pot cleaning part, as I have always thought washing pots was a waste of time.

    Reply
  11. This was an excellent post. It is so helpful to see some of these myths busted! For example, for years after I planted all my plant babies outside, I would throw all my containers into my large plastic buggy, swish them around and then rinse them and let them air-dry. Then I read the part about having to disinfect them, so I used bleach for a few years. In spite of the fact that I had never had any difficulties with my seedlings over a period of at least a decade of seed starting. So thanks to your article, I am going to skip the bleach again! I shared your article on Facebook! Thank you again.

    Reply

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