Interlude Presentation #1: Seed Germination Testing
First, what is an "Interlude Presentation"? Well, it could be that I don't have the next regular presentation ready yet, but a timely topic has come up that I feel I need to share. Or, it could be that there's a semi-related topic that I feel is beneficial to insert. In this case, the pandemic sent everything sideways before I could get to the next presentation, but something on seed testing is needed now.
What is seed germination, and why test for it?
Here's a Wikipedia definition for germination:
"Germination is usually the growth of a plant contained within a seed; it results in the formation of the seedling. It is also the process of reactivation of metabolic machinery of the seed resulting in the emergence of radicle and plumule."
The "radicle" means the beginning of the root. The "plumule" is the beginning of the stem and first leaves. These are most easily seen by soaking a bean seed and watching it start to grow.
Check out this little video:
https://www.youtube.com/watch?v=pg92cspLy0I
But, why test seeds for germination?
You can save seeds, and save money.
You may have seed left over from last year. Maybe you didn't need to plant all the seeds from a packet, or you have a packet you didn't use. Or, you saved seeds from plants and vegetables you grew last year (saving seeds will be a whole other presentation sometime) and need to know how good they are.
Are they still good? Will they grow at all? If they do, how many will grow? Instead of buying whole new seeds, it's possible you could use what you have, which will save money.
And if you have saved seeds from heirloom plants, that means you are also saving heritage, or you have been selecting for certain traits, and you want to be sure these seeds are going to work this year.
And, instead of taking the chance and possibly wasting space by planting seeds that might not come up, or would come up poorly, you can test your seeds to see if they are worth taking the chance.
In other words, you want to know how many of your seeds will actually sprout.
The germination rate has to do with the percentage of seeds that sprouted from the total number, within a certain period of time. You can use that final percentage to determine if your package of seeds is worth saving and planting. More on that in a bit.
Seed companies test seed for germination rates before packaging and selling them, and some print the % germination on the package. They also print a date for when the seed was tested, or when it was packaged, or when it was "packed for". If your packet is beyond the year noted, you may need to do your own, updated germination test.
And, that test is very easy to do!
How do you do seed germination tests?
The following is a series of photos showing the process I use. Sometimes I use the "paper towel method", and sometimes the "coffee filter method".
I normally will put 10 of a type of seed to the test, and this is because it's really easy to determine the germination rate with 10 seeds. If all 10 seeds germinate, it's 100%. If 5 seeds germinate, it's 50%. You get the idea. I will keep seeds to plant that test 90-100%, for sure. Sometimes I'll take a chance on seeds that test at 80%, if I just really want to get something out of them.
Sometimes I'll test only 5 seeds if I don't have very many seeds left (or if they are very large). The percentage is not as easy to figure out, but you can guesstimate pretty well. Ten is best, though, and more reliable.
I'm sure seed companies test with a much larger number of seeds, but the home gardener doesn't usually have that luxury.
Let's start with the "paper towel method". The first examples use Luffa seeds, which are very easy to see. These Luffa seeds were saved from Luffa gourds I grew two years previous.
Here, I have set out one sheet of paper towel and sprayed it with water so that it is pretty wet but not soaking.
A dish of Luffa seeds is ready, with packets nearby of other seeds I want to test.
With the "paper towel method", I test more than one kind of seed at a time. When possible, I try to use the same types of seeds (such as beans, or lettuces) on a section of towel, or certain sizes of seeds (tiny, medium, or large).
And, after saying that, here I have different sizes and types on one towel. :D
Notice that I have 10 of each kind of seed. Notice also that I've labeled each on a strip of paper. I can't emphasize enough that ... LABELING IS VERY IMPORTANT!! It's way too easy to lose track, and in seed testing that can be very frustrating. Not good labeling = not viable testing. On each of these labels I've put the type of plant (e.g. Cabbage), the variety (e.g. Kalibos), the source of the seed (either the seed company or what garden it was saved from) and then either the year of the seed packet or the year the seed was saved from the garden. This helps me make a definite match later to my store of seeds. So, I have: Luffa (no variety), saved from my home garden in 2018, and Kalibos Cabbage, a packet of seeds from Pinetree Seeds company in 2020.
Next, place another sheet of paper towel carefully over the sheet of seeds, and spray it with water so it's pretty wet but not soaking.
Then, carefully roll up the paper towel seed test. Label the whole roll! This way, you can tell at a glance what seeds are contained in the roll - this makes things much easier. Place the roll in a plastic bag (such as a gallon-size freezer bag). As you do more paper towel seed tests (if you need to do more), keep labeling the rolls and placing them in the bag.
Then, place the whole bag in a place that will stay warm! I put mine on top of the refrigerator, which is always giving off some warmth. Other good spots are on top of a freezer or hot water heater, in a sunny window spot, near a heating vent. They need to stay a little warm, but not hot!
BUT, WAIT!!!
Before you roll up those towels and put them in the bag, there's another VERY IMPORTANT thing you need to do ...
You need to keep good records! How you do this is up to you, but here's what I do.
I use a sheet of notebook paper and make columns (some people like to use computer spreadsheets, but a notebook works fine for me). At the top I put the year. Since I work with a number of different garden sites, I also note at the top which garden the seeds are for.
The first column is for the date the seed test was started. You might do all of yours on one day and just need to put that date at the top. I have so many to do for different gardens that I end up starting groups of them on different days, and it's very important to keep track of the day you started a seed test!
My second column is for the "type" of crop, such as pea, lettuce, summer squash, pole bean, flowers, etc. My third column is for the particular variety (such as "Kalibos").
The next column is for the seed origin - the seed company and year of the seed packet, or the garden saved from and what year the seed was harvested and saved.
The next columns are for keeping a record of germination rates. I check them at one and then two weeks, so I put down the date for each germination check. In those columns, for each crop, I note the percentage germination. It's simpler to just check them at two weeks, but be sure to write down the date.
The last column is for - keep or toss? This makes it easy for when the tests are all done and I go through all my seed, getting rid of those that didn't test well.
And, here's my next set of paper towel seed tests getting started (it helps to have a cup of tea handy). You can see that, on my record sheet, I've drawn a line between sets of tests. Another simple thing to make things easier later.
And here's another seed germination test being set up with paper towels, this one all for heirloom beans. You can see that I only used 5 beans for a couple of varieties because I just wouldn't have enough beans left for planting if I used 10 for testing.
Now it's time to show you the "coffee filter method".
This is even easier than the "paper towel method", and it may be easier to keep track of seeds. It's especially good if you don't have many kinds of seeds to test (if you have many, as I do, it would be too many coffee filters), since you only use one kind of seed per coffee filter. I also like to use this for large seeds, such as the larger bean seeds - it's less cumbersome for those than using the "paper towel method".
First, LABEL your coffee filter! Use the same information that I showed for the "paper towel method" labeling - type of crop, variety, source, and year of seed.
Then flip over the filter and spray it with water until it's very wet but not soaked.
Place your seeds in the center area (in case you are wondering, these are Purple Koronis Bush Beans, saved from my garden in 2017).
Then just fold the sides of the wet coffee filter over the seeds so you have a nice little packet with the label showing on top.
As with the paper towel tests, place them in a plastic bag and set in a consistently warm place.
Then, leave your seed germination tests in the warm place for two weeks. Most seeds will germinate in two weeks (there are a few kinds that take longer, like parsley - find out if they are typically long-germinating and leave them in another week). I like to check mine after a week because some seeds (like beans) germinate quickly, and I am impatient about finding out. :) But, I always leave the tests for two weeks.
Checking the tests
After two weeks (or one, if you are impatient and want to see what germinated early), start checking your tests - carefully opening the coffee filters or, even more carefully, unrolling the paper towels. Just take out one set of coffee filter or paper towel tests at a time so that you can keep track of them better.
One disadvantage to the "paper towel method" is that some seeds go really crazy germinating, their roots growing through the paper towels. This can make it more difficult to unroll the towels, and sometimes also to determine which seeds were which, if they get pulled out of place. Unroll the towels as slowly and carefully as possible.
In the above photo, you can see the plastic bag with both paper towel and coffee filter tests. It is also easy to see which beans have germinated. This was after just a week, so I will still roll this back up and leave it in the bag for the full two weeks to see what the beans did that had less germination after one week. If you are not impatient, you can just wait two weeks to begin with. :)
You can also see that my record sheet is at-the-ready, and you can also see how important all that labeling is.
It's not super clear in the photo, but the first beans (right), the Sieva Lima beans saved from the 2020 garden are only at about 50%. If this is after one week, I would roll them up and leave them in the bag for another week. If this is after two weeks, that means I will toss them - 50% germination is definitely not good enough.
You can see that germination was very good for all the other beans. They are all 100% (there may be one at 90% here - nine beans germinated, but not easy to see in the photo). The packets of these kinds of beans are ones I know I can plant with success.
As I go through them, I write the percentages in the correct columns on my record sheet.
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At the end of all testing, I check my record sheet with my packets and containers of seed and remove any that did not test well enough. With the remaining seed that tested well, I can now decide if there are any seeds I still need to purchase (or, get from a friend who has tested seed, or from a seed library - sharing is good!). I can also start making my garden plans!
One more note on choosing which seeds to test: there are some kinds of seed that have very low viability after even a year. Onion seed is one example. For these, don't bother keeping any seed beyond the year, unless it's seed that you saved from your most recent crop. Check the year on seed packets and don't keep these seeds beyond that year. There are charts you can use to determine this (see links below for two examples). This will help you determine what seed to keep, to take a chance on, and what is worth the effort of doing a germination test.
http://my.chicagobotanic.org/wp-content/uploads/Seed-Viability-Chart.pdf
https://www.highmowingseeds.com/blog/seed-viability-chart
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Now you are ready to do some simple seed germination testing!
In at nutshell:
Supplies needed:
Paper towels and/or coffee filters
Strips and paper and (non-bleeding) pen
Spray bottle of water
Record sheet (whatever form works for you)
One or more plastic bags (such as gallon freezer bags)
Seeds that you want to test!
Basic directions:
1. Set up your record sheet with labeled columns
2. Select what seeds you want to test
3. Select 10 seeds from the first kind you want to test (10 that look like they have a good chance of sprouting)
4. For "paper towel method": Wet one sheet of paper towel. Place 10 seeds in a row and be sure to include a strip of paper with the crop and variety name, the company (or garden saved from), the year on the seed packet (or year saved from a garden). Continue until the the sheet is full with different types of seed, or until you have done all the kinds of seeds that you want to test. Write all the information on your record sheet, including the starting date. Cover with another wet sheet of paper towel. Roll up carefully. Add a label with a list of general contents. Put in a plastic bag and set on a consistently warm place.
5. For the "coffee filter method": Write on the coffee filter the same information as above. Wet the coffee filter. Place 10 seeds in the middle (of just one type). Write the information on your record sheet, including the starting date. Fold up the coffee filter sides over the seeds to cover them, with the label showing on top. Put in a plastic bag and set on a consistently warm place.
6. After two weeks, carefully open up tests, one at a time, to check. Note how many seeds have germinated for each type, and figure the percentage germination. Write the percentage on your record sheet.
7. Now you can go to your store of seeds and toss out those that did not germinate well, know what seeds you may need to order, and can start planning your garden!
Terri
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