What Doesn’t Work For Germination And Sprouting
1. First, you can accidentally kill your seeds with a strong enough application of cold, heat, moisture, or a combination of these three. This can happen at home if you leave the seeds outdoors overnight, leave them on a sunny windowsill or in the sun anywhere (where the seeds can get up to 140 degrees on a really sunny day!), or let the seed packets get damp or wet (they will mold then!). So, keep seeds dry and warm indoors until you need to use them, then get them back to a protected spot as soon as you’re done. It’s really difficult to get dead seeds to germinate!
2. Don’t use peat or store-bought “potting mixes” instead of the coco coir/vermiculite mix we recommend (we’ll call it CV from now on for simplicity). First, these types of potting mixes hold far more moisture than the CV mix does, and are less “airy”, allowing less oxygen to the developing plant’s roots, if used in a flood and drain sprouting table. As a result, the plant roots often simply rot off, or “damp off”, and die at some point in the sprouting table.
In addition, these types of potting mixes often bring pythium or fusarium molds along with them, even though they say they’re “sterilized”. Both of these molds can become epidemic in your aquaponic system given the right conditions, and can also be difficult to get rid of. Don’t take the chance, there’s no cheese at the end of this tunnel!
3. Don’t use dirt instead of the CV potting mix! Plant roots develop differently in dirt than they do in the CV potting mix, and appear to simply rot off, or “damp off”, and die when they’re put into the rafts where their roots are wet all the time.
4. There’s no need to use larger, more expensive pots (that occupy more aquaponic “real estate”): we grew a 7-pound taro and a 2.87 pound turnip (root vegetables) as well as bulbing onions, in 2-inch pots. They simply grow on top of the raft. We never use 3-inch pots now, because everything grows just fine in 2 inch pots, and we get far more of them into every square foot of raft space, which equals more production from the same-sized system.
What follows from this (of course!) is that there’s also never any need to “repot”; that is, take a plant out of a small pot and put it into a bigger pot. This is a good way to either kill a young plant or retard its growth so that it never achieves full size.
5. Don’t “recycle” your CV potting mix. We found when we re-used our potting mix that our “germination rate” dropped to 50% (this means only half of our seeds sprouted). We don’t know why, but we do know enough to stop doing things that don’t work.
6. We tried using red and black volcanic cinder for potting mix. The black cinder worked great! The plants grew better, faster, and had excellent germination rates. Except that after two or three planting cycles, the pots started shredding and we had to throw them away.
We found that when the plant’s roots grew, they forced the cinder out through the sides of the pot, breaking them. We’d gone from throwing away CV planting mix that cost us $0.001 (one-tenth of a cent) each planting cycle to throwing away pots that cost us $0.03 (three cents) after two or three uses (and we didn’t actually “throw away” the used CV mix; it went into the compost, and was of further benefit to our farm there). Our potting expense went up by a factor of ten as a result of this, and we were throwing away a “non-recyclable” plastic pot instead of recyclable potting mix.
This is hugely important for a commercial operation. Even at the small scale we operated at, this added a penny to each month’s cycle of 25,000 pots, or $250 per month and $3,000 per year. Every little bit counts when you’re running a commercial operation!
7. We also tried “rock wool cubes” with less than inspiring results; we used the “Oasis cubes”, plus other brands. Our results included poor germination, much higher costs, and more labor when compared to using the CV potting mix we recommend.
8. There’s also no need to use expensive potting media such as Hydroton or other expanded media. The CV mix we recommend is economical and widely available.
9. If you are tempted to use Perlite (because we haven’t said anything bad about it yet), take a handful of Perlite and throw it into a bucket of water. You’ll notice that some of it sinks, some of it floats, and some of it is almost perfectly suspended in the middle of the bucket. Now take another handfull of Perlite and grind it together between your hands; notice the abrasive, sandpaper-like dust that results?
We shudder at the thought of Perlite loose in our systems, floating through at all levels from the water surface to the bottom of the tanks, abrading our pump shafts, impellers, and seals with each pass through the pump. We shudder even more about the possibility of it going through our fish’s gills until the fish died suffering from the abrasions on its breathing surfaces. You can try it, we’ll pass.
10. After the starts reach their optimum maturity in the sprouting table (which is when the little plants are about 1-1/2-2 inches tall, and their roots just barely start coming out of the net pots into the plastic trays) they get moved into the rafts in the Aquaponics system. You may be tempted to “let them get a little bigger and stronger” before the transfer. Don’t wait longer!
If you wait too long to take the sprouted pots out of the trays, the roots will be tangled with the hole or the mesh at the bottom of the tray, and will rip off, “shocking” the little plant. This shock can be so severe that the plant doesn’t recover much, or at all, and will never grow well. So be sure to take your babies out of the sprouting table and put them into the system rafts at the appropriate stage of growth.
11. Conventional university sprouting methods involve putting the seeds into potting media in net pots in some kind of a plastic tray that holds a bunch of them for easy handling, then they go on a nursery table (which is a wire-topped table that drains excess water out the bottom of the wire onto the ground). You water them with an overhead spray or by hand-watering using tapwater until they sprout and you put them into the rafts in the aquaponics system. Sprouting this way involves a lot of hand labor in the watering, and since it does not use any kind of nutrient solution for watering, the sprouted plants grow more slowly than is possible with other methods. It’s a waste of your time.
12. We tried putting the net pots directly into the system rafts, and they sprouted and grew just fine. There were two problems, though: it used up a lot of aquaponics “real estate” that could have had more mature plants in it making money for the farm; and about 30% of the plants sprouted in this fashion simply rotted off at the roots and fell over, requiring replacement. It’s a waste of your time and your system real estate.
13. We tried vacuum seeders, because the university recommended them. These hook up to a vacuum cleaner and hold your seeds in place. When you turn the vacuum seeder upside down over a tray of pots, then turn off the vacuum, all the seeds drop conveniently into the centers of the pots. Fortunately Tim knows how to make stuff like this, so we made two excellent vacuum seeders (of slightly different designs) rather than purchase two (for up to $675 each). Although both these seeders worked as well as the commercially available ones, what we found is that even the commercially available ones don’t work that well. Even after we got fast on the vacuum seeders, we found that the same person could actually seed 50% more in the same time by hand seeding.
14. If you let the sprouts in the sprouting table go “too long” between waterings, you can “shock” them, which can make them grow poorly or not at all during the rest of their life. We had some plants that just didn’t do well at all, and when we analyzed the situation, we found out an employee had neglected to water them for two to three days at a stretch. This wasn’t enough to kill them, but was enough to shock them so that they wouldn’t grow. If you can identify a “shocked” batch of seedlings like this, throw them away and start over! They will never grow! And water your sprouting tables once a day after this, like clockwork!