Questions RE: SeedStarting

Blomma and Heathrjoy and others,

Freezing artificially can hurt seeds primarily in two ways. The first is through desiccation particularly with self defrosting freezers. The second way is as heathrjoy mentioned through membrane rupture by the formation of ice crystals. Both of these types of injury depend on a lot of factors including species, time, moisture content of the seed, and rate of temperature decrease.

The interaction of seeds with temperature and moisture is a very complex chemical/physiological process that is much too complicated to go into depth in this forum, but in general, imbibed (and dry) seeds survive cold through supercooling (lowering the temperature of a liquid with out it crystallizing into a solid) and/or through the tolerance of desiccation. These processes occur just fine in nature, but when we start germination according to our schedules (and methods) we can disrupt these and cause seed death.

In nature, plants (seeds) have evolved physical and chemical properties which prevent freezing temperatures from killing them. Many seeds survive cold temperatures with hard seed coats that inhibit imbibing until that coat has been worn down by time and temperature fluctuations. We can easily overcome this adaptation by nicking or scratching the seed coat (scarification) and thus allowing us to germinate these seeds when we want, not when nature dictates. Other plants (seeds) survive through a chemical process that prevents germination until some cycle of temperature variation occurs (in the presence of moisture) called stratification. Again, this is highly species dependent and in some, repeated cycles of cold/warm is needed for germination to occur. Germination inhibition broken through stratification is a chemical/enzymatic reaction that occurs above/below temperature thresholds for a given length of time. Interestingly, this type of dormancy can also be artificially manipulated through the use of GA3 and other plant hormones (sometimes with very bad side effects). Another plant homone abscisic acid (ABA) can increase freezing tolerance compared to water imbibed seeds.

Bottom line, nature can take care of itself, but if we want seeds to germinate on our schedule, don't store seeds in the freezer, nick and soak when necessary, and if stratification is needed do it with moisture in the refrigerator or WS.

Hope this helps.

I wondered if the seed orders being shipped in the middle of winter and left in the mail box until I got home after work would be a problem for the seeds. These packages arrive frozen. I do not think it affected the seeds, otherwise the seed companies would not ship them.

Joannabanana, it all comes down to moisture levels. Seeds in storage have very low moisture levels and when frozen, do not form ice crystals and thus are not hurt by periods of sub freezing temperatures.

When seeds are frozen for long periods of time (months), species can vary widely in their survival. I've had numerous packs of seeds that have been left in the garden shed over winter, some of these seeds have been fine, and in others germination drops to almost zero.

Hey. I'm looking for some feedback from some experienced seed germinators. I'm working on a project as a student that involves a flat packaged polyethylene container that is designed to function first as a greenhouse and second as a planter, which eventually leads to hardening and transplanting. My blog is http://theopenlair.blogspot.com/

I would appreciate any feedback. Please check it out. My containers for the germination that also change into the pot are designed to be flat packed so that you can easily store them away without all the bulk and clutter.

Excellent idea candace for an adhesive gorrila glue will hod anything just brush on a little water(very little) and a thin bit of GG and it will hod anything. I wish you luck because I think its a brilliant consept.......rucky

Thank you for your feedback. I got some GG around here somewhere.

This my first time starting plants indoors. My husband bought me shelving with plant lights. I wanted to grow spinach to eat during the winter. My spinach only sprouted 2 out of the 50 peat pellets I planted. I have them covered, not in sunlight. They are moist, not soaked. They are in my diningroom which is between 65 and 70 degrees. Do they need to be warmer? If so, can I just use a regular heating pad or do I need to invest in a heat mat especially for germination? Thanks for all your help!

sunny, spinach will germinate between 40 and 75 degrees F. Obviously, the warmer they are the faster they will germinate, but the percentage germination drops off rapidly when they get too warm. Do not use a regular heating pad for germinating seeds. They aren't rated for that kind of use.

If I was going to try to grow spinach inside, I would use a window planter box (approx 6" x 18-24") filled with a good potting soil and scatter a healthy amount of seed randomly in the box about 1/2 inch deep. Spinach does not like to be transplanted, so I would use this method rather than trying to seed in individual peat pots.

Spinach likes a pH of around 6 and the low pH of the peat pellets could be inhibiting germination. A good potting mix should have a higher pH than peat pellets and you should see higher germination rates.

Try to germinate the spinach in this way:
Put your spinach seeds inside a glass jar and cover them with sand (just enough so you will not see the seeds).
Add a few drops of water, close the jar with the lid and put it on the refrigerator.
When the seeds will start to sprout, you can plant them outside.
Spinach really like the cold weather.

drthor ~ Have you germinated spinach in a jar then put them outside in January?

yes, I germinate in this way lots of cole crops that need cold to germinate.
Try it ... you will be surprised.
Actually last week I planted some spinach seeds I left in the fridge for one week, no sand or jar. I just want to give them the cold snap ... I will see what happen.

Oh, the possibilites are endless. Last year the cool-season crops did better than the warm season ones due to late cold weather during spring, as we had snow on May 16th, rain a few days later, and then the next week in hail. usually May is the nicest month and it is usually all the spring we get, though off and on, any year has variations.

OK, I will try more broccoli, as we eat that and lettuce the most. So, broccoli, cabbage, lettuce, onions, cauliflower, and peas. I already have 12 broccoli and 6 cabbage and 6 Chinese cabbage growing now. These take up quite a bit of room as they are in square foot gardens. (4' X 4' X 1') I suppose I could start the carrots early as well. My parsley is growing since last season, so I guess I'll save the seeds come summertime.

I'm facilitating a workshop on seed starting 101 and if you would like to see a copy of the slide presentation, please d-mail me and I will let you know how to access it. I'm not sure how to upload a pdf file on DG


This message was edited Jan 8, 2011 3:47 PM

I like this source for info about what kind of pre-treatment each type of plant prefers to maximize its germination rate.

Virtual Seeds Seed Germination Database
http://www.virtualseeds.com/Germination.html

You can copy the "database" part as a plain text file and then search it. Or, import it into an XLS sheet.

The following seed germination guide is property of Thompson & Morgan.
This guide is out of print and not property of Virtual Seeds.
This guide is provided for personal information only.


Corey

Diane's Flower Seeds, one of the Top 30 companies at the Garden Watchdog, has awesome "Articles" where she describes several "special treatments" that can improve germination. Check out her extensive shop for some rare, heirloom seed varieties too. Hope this is helpful! Happy Gardening everyone!
Love,
Ella