How did we ever grow vegetables, or any other transplants, without plastic pots? Clay pots have of course been around for a long time. But these are heavy, breakable, expensive, and are not made with all the refinements plastic pots offer for encouraging a good root system.
If you really want to ditch plastic pots, you can just grow your seedlings out in the garden, smack in the soil; but there are several tactics to making sure your green efforts are a success.
In almost all cases, seedlings like to have light, warmth, and protection from wind. Ideally your whole garden would be a sunny, protected spot, but selecting the most happy, cozy little niche in your yard for your seedling nursery is imperative. These are babies you know.
Fertile, friable soil.
Just remember this point as the two F’s. In this case, the F’s are not for failure, they are for success.
The natural strata of soil keeps the fertile, nutrient rich organic matter on top of the soil, with poorer soil lower in organic matter lower down. Seeds usually sprout on the soil surface, so it makes sense that seedlings are wired to use lots of nutrients as they sprout.
Planting seedlings in poor soil without organic matter is the exact opposite, and usually gives poor results.
Friable soil is crumbly soil. Rich soil high in organic matter is very friable. Sand is another friable soil type.
You want your soil to crumble easily, because you intend to transplant these tender little seedlings. If your seedlings are stuck in rock hard clods, you’re likely going to break a lot of them in transplant, and stress them far more than if the soil just falls off their roots.
Best situation would be to mix sand with a soil high in organic matter, or to have sand a foot deep, with a few inches of organic matter rich soil on top.
If you’re growing out tree seedlings especially, you will want that foot or so of sand. This will accommodate the deeper roots.
In general, sprinkling the seeds around randomly takes up a lot of space, and often gives a chance for weeds to show up in the un-used space between sprouts. Not good.
It’s often better to space out seedlings in time rather than space. In this case, start out seedlings close, in rows or patches, so they take up the minimum amount of soil for their size, and transplant to larger spacing as they grow.
Some seedlings you will only want to sprout before transplanting to their final positions. Other plants, such as young trees especially, you will want to grow out in the nursery until a descent root system has formed. This may take months, and probably two sequential transplantings -one from the sprouting bed, and one to more spaced patches or rows -before transplanting to their final position.
The secret to success here is getting to seedlings transplanted on time. Seedlings right next to each other will shade each other’s stems. This will induce the production of hormones called auxins. These elongate the cells, making the seedlings long, spindly, and weak. The way to avoid this is to keep an eye out for sprouts, and never let them grow too close for too long. For some plants, sprouting happens over several weeks. In these cases, just dig out the little seedlings as they come.
A major problem with seedlings can be damping off. This is when a portion of the stem looks like it is pinched, and shrivels up, or that seedlings don’t sprout at all because they have rotted below the soil.
Conventional methods dictate attacking the problem directly with antibacterials and fungicides mixed into the soil, or sprayed on the seedlings. Some organic methods spray the seedlings with infusions of thyme or other organic antibacterial herbs. A better method is to just provide a situation that doesn’t support the disease through proper design.
Damping off usually occurs in low temperatures, or excessive moisture. A warm position with well-draining soil already gets you ahead in keeping away from damping off; but there are some tactics to improve the situation even more.
For instance, raising up soil the seedlings are in, such as in raised beds, will bring the soil closer to the temperature of the air. This may be a bad or good thing if the space is outdoors, as cold snaps may mean the soil is warmer than the air. In most cases, and especially if the position is protected, the opposite is usually the case.
You can also increase the temperature of the soil by increasing its solar exposure. One way to do this is, again, to raise the soil. The solar exposure is further improved by forming the soil in curved, S-shaped ridges.
This works because sunlight interacts much more with soil when its surface is near perpendicular to the slant of the sun. Raising ridges like this also increases the overall surface area sunlight can hit. The more surface area sunlight hits, and the more direct the hit of sun, the more warmth your given sunlight will warm the soil.
Poor air circulation also encourages damping off. Don’t take this to mean your area should be exposed to wind. We already discussed how young seedlings don’t like that. A better way to minimize poor air circulation is to not let seedlings stand together too close for too long. Again, pay attention to timing.
Following these directions, you have the best chances of growing healthy seedlings without plastic pots. I’ve learned a lot of these tactics from watching experienced gardeners put them to use. I am always interested in learning about new tactics that can be added to this practice. If you know any, I’d love to hear about them.