Seed Coatings and Storage?

[Greatgardens]

Has anyone read about (or tried!) any experiments with seed coatings (either organic or inorganic in the chemical sense)? I have read that most seeds "dying" is from dehydration over time. If that is correct, then it seems like some type of coating similar to the food wax used commercially on fruits could be used to prolong seed life. Particularly if the coating also had some antibacterial properties.

My second question is more mundane. When you see "dark seeds," are they typically defective? I find normally on a ripe tomato that saving seeds will produce maybe 1-2% "dark seeds." Sometimes they look otherwise perfectly normal. I always cull them, but I also do find them frequently in commercial seed packets.

-GG

[ddsack]

I don't know about the coatings, I generally get adequate germination from tomato seeds up to 10 years old and don't store them in any special conditions.

I was curious about the dark seeds a couple of years ago, so saved out the dark seeds from various drying seed batches and germinated them. I found that between 10-20% will germinate normally. I didn't keep any records the first time I did this, but the second time I saved seed from 12 varieties for a total of 171 dark seeds. Only 25 germinated, which is close to 14-15%. I didn't separate out the all dark seeds from the partially dark pinto seeds, so that could make a difference in which germinate. So my conclusion is that if you have a lot of seed for a variety you might as well discard them, but if it's few seeds for a rare variety doesn't hurt to give them a try.

[Nan_PA_6b]

I tried germinating the "pinto" ones- light seeds with a black spot or two. Those germinated at a pretty good rate.

As for a waterproof seed coating, I suppose it would keep out the water when you planted the seeds, and thus inhibit the germination? Instead, how about something like those pelletized coatings they sometimes use? It would be water-permeable, but still be an extra layer of "insulation" to keep the seed from drying out.

How about packing them in something like sawdust or sand? If the medium had the same percent H2O as the seeds, would it keep the seeds at proper moisture longer? No %water differential between the two.

Or what if you vacuum-sealed the seeds, like Seal-A-Meal, so there is nowhere for the seed moisture to go?

[slugworth]

A tomato seed packet from botanical interests had the seeds in a foil pouch.
It is the 1st time I have ever seen tomato seeds like that,normally only pepper
seeds.
The seeds germinated better than fresh seed recently bought.
The seeds were 3 years old.

For dark seeds, I think it depends on why they're dark.

I had no trouble at all sprouting tomatoes I received in a trade once where every seed of the variety (which was coincidentally named Black) was dark. When I saved seeds from my Black tomato fruits, the seeds weren't dark; so, I'm guessing it was stains from the fermentation or something. From my own saved seeds (and I save a *lot*), I've only had a batch of seeds be dark like that once that I recall, and that was with an overripe Black from Tula fruit (every seed was dark; they were dark without fermenting them; I haven't tried sprouting them, but I suppose they will sprout). My guess is they just experienced some weird fermentation or staining in the fruit or something. As long as they're not rotten, they're probably fine. Taking the seed coat off may reveal things. I'd take precautions against disease anyway, though (just in case; I zap my seeds with a Z4EX; some people might soak with a little bleach or hydrogen peroxide; some people might re-ferment them).

When seeds rot, it usually starts with a spot on them, rather than the whole seed being dark, in my experience (it sounds like even some of those with spots might sprout, though!). If the whole seed is another color, they may be fine. Some tomato seeds are other colors besides dark and the regular tomato seed color. Most seeds are normal under a UV flashlight, but I've noticed that a certain percentage of them seem to get the same look that a milk jug gets under UV light (but it's just the color; the seeds can sprout). I wonder if those seeds block UV rays and are capable of staying viable longer in the sun.

Anyway, as my experience with dark seeds is limited, take it with a grain of salt.

The dark seeds might even be a genetic trait that just doesn't show up all the time, but I think it's likely just stains.

Some seeds come coated in stuff. I think that's just to make them visually easier to distinguish between other seeds made other colors in the same packet, but I could be wrong. It might extend the life of the seed.

One seed store I shopped at once vaccuum packed its seeds for extended shelf-life.

The ancients (or people hundreds and/or thousands of years ago) sometimes put seeds in clay balls in caves. People discovered some of those and found they were still viable after a super long time. Maybe perfect the art of making clay balls! It's probably very doable. Having your own cave might be a little harder, but we don't know if the cave is necessary. Maybe use a root cellar, or just put them wherever. I imagine the clay insulates well.

They put other things in clay balls besides seeds, though (e.g. some valuables; perhaps jewelry).

[Greatgardens]

Usually, the coating on seeds (not "pelleted" coatings) is some form of fungicide. It can help germination under poor "soil" conditions. For some direct-planted crops like peas or super-sweet corn, it works great, especially in colder soil; for tomatoes, probably doesn't do much one way or the other.

In my own experience, I believe that my seeds now last longer, because I have stored seeds in little plastic bags and keep all the packets in a zip-lock bag with a silica gel packet inside. It is pretty easy to still get 50-60% germination off tomato seeds that are 10 or 11 years old. But it does take extra time -- usually two weeks. I had this experience with "Vilma" this past January with two batches of seeds -- 9 and 10 years old. Also, older seeds in unopened Park's "Paks-O-Gold" that the former owners used always seemed to provide better than expected germination.

Once, when talking to Tomato Growers Supply, they explained that some (new-old stock) Burpee Orange Pixie hybrid seeds that I wanted were going to be taken out of an unopened can, and ultimately, they germinated great for me. Now admittedly, for most of us, that is totally unnecessary, especially if growing OP varieties. For hybrids, it might be more useful, if you get one that you really like. You never know when it may no longer be available.