Sowing seeds right in the ground skips the whole container issue, but there are many perils too, and great potential for losses, particularly when you’re dealing with tiny seeds or small quantities of very special seeds. Containers give you much more control over the germination environment, but not all containers are equally desirable, depending on the circumstances. I prefer to use plastic pots (more information here) but have tried many other options over the years and figured I’d say a bit about them.
When I have more seeds than pots, I’ll use anything I have on hand. Below are some of the options I have tried with varying results. Most of these reused or repurposed containers can work in a pinch for common flowers and veggies, but don’t expect them to provide optimal results if you start trying to grow more unusual kinds with longer germination periods.
Cell packs and plug trays: These plastic containers have multiple linked cells. You may end up with some of these from buying small flower or vegetable transplants or collections of perennial seedlings from online nurseries. They can be ok for sowing fast-growing annuals, like lettuce and basil, which germinate quickly and are ready for transplanting soon after, but they take up a lot of growing space and usually don’t hold much growing medium so are hard to keep evenly moist, particularly for seeds that won’t germinate for many weeks or months.
I usually save these sorts of containers for potting-up seedlings, not seed sowing. If you do try to use them for starting annual seeds, don’t be tempted to plant different kinds of seeds in one pack or tray, unless maybe you plan to cut the cells apart later. (Individual cells are very prone to tipping over, though, so I don’t advise doing that.) The different kinds of seeds will likely germinate at different times, and some cells will end up ready for transplanting while others haven’t spouted yet or are still tiny, and it gets tricky to remove some without disturbing others.
Peat pellets: These are round disks of dried peat that swell up into little netted blobs when put in water. They may be convenient, but I have had too many problems with them to like using them. They are so hard to keep at the right moisture level and tend to develop fuzzy mold in very humid conditions, and it’s very difficult to separate seedlings if you sow multiple seeds in one pellet. Some people really like peat pellets, and I guess these are all right for easy-to-handle, fast-germinating seeds like tomatoes and zinnias, but I would not recommend them for very small seeds, or for those that are likely to take more than a few days to germinate. I cringe when customers tell me they plan to use these for seed-sowing, because I know I am likely to hear back from them that they are disappointed with their results.
Peat pots: These are small, round or square, single-use pots made of tightly compressed peat, which you then fill with another growing medium. (I’ve seen similar pots made from pressed wood fibers, or composted manure.) I have some of these but rarely use them. As with pellets, I find it’s difficult to keep them evenly moist, and if they dry out, they can be hard to re-wet. They can be ok for squash, cucumbers, gourds, and other large, fast-growing seedlings, but I personally wouldn’t recommend them for starting most of the seeds I sell.
Fiber packs: These are kind of like peat pots but are small rectangular trays instead of pots. You see these less often these days but may still acquire some when buying vegetable or annual transplants. Rather than throwing them away or composting them, I mostly save them for potting up seedlings but occasionally use them for sowing large, fast-growing seeds that won’t be in the pack very long, such as beans, peanuts, or nasturtiums. In my experience, fiber packs are too hard to keep evenly moist for small seeds, or for those that take more than a week or so to germinate.
Egg cartons: These are free and easy to acquire, but again, I don’t recommend them for most seeds. The individual compartments are too small to hold much growing medium, and the cardboard ones draw out the moisture quickly, so they need frequent watering. They may be all right for fast-germinating seeds, but the seedlings can’t stay in there long.
Paper pots: It’s easy to make free, short-term containers from strips of newspaper wrapped around anything from a small vitamin bottle to a soup or soda can and then fill them with growing medium. They can be very handy for fast-sprouting seeds, and you can pop the whole thing in the ground at transplanting time. But once you add the growing medium, the moist paper gets soft quickly, so the “pots” won’t last long. Again, paper pots can be fine for fast-growing annuals and veggies but not for seeds that may need longer than a week or so to germinate, or that need to grow for more than a week or two before transplanting.
Soil blocks: You can buy specialized molding tools that form moistened growing medium into blocks for seed-starting (like this one from Gardener’s Supply Company). I have not used them myself because they are kind of pricey to buy, and you have to purchase several to get a variety of sizes. I also doubt that the blocks would hold their integrity more than a couple of weeks, which would be problematic when you are waiting for seeds that take many weeks or months to sprout. On the other hand, they are cost-effective if you are raising a lot of fast-growing annual seedlings, because the block-makers last for ages and you aren’t having to deal with pots each year.
Here are a couple of options I have had really good luck with and use often, particularly for seeds that need a chilling period at some point during their germination process.
Paper towels: Fold a half-square of paper towel into a little “book,” spread the seeds inside, add water so the paper is moist but not dripping, close the and then slip it into a plastic sandwich bag. You could use one plastic bag for each and label the bag, but in an effort to minimize plastic use, I usually label each paper-towel pad, writing the name and sowing date with a fine-tipped permanent marker, and put several pads in one bag.
Using this approach ensures that the seeds stay evenly moist, and it is so easy to put the bags in whatever conditions the seeds need: under lights indoors for extra warmth, on a kitchen counter in a warm room, or in a refrigerator for chilling. You do need to check them regularly, particularly in warm conditions, to catch the seeds just as they sprout but before they send roots into the paper; otherwise, it’s challenging to separate and pot them up without damaging the roots. (If you do miss the ideal window, just tear the towel carefully; it’s ok if there is still a bit of paper towel on the roots when you pot up the germinated seeds.)
Paper-towel sowing doesn’t work well for very small seeds, which are particularly hard to handle once they start sprouting. But this approach is a huge space-saver for slow-germinating seeds (no need to have dozens of pots taking up space for weeks or months while needing careful watering), and for seeds that need alternating warm and cold periods. It’s also handy for giving larger seeds, like sweet peas and morning glories, a jump-start before sowing them in the garden. I recommend giving it a try even with easy seeds if you enjoy watching the germination process. It’s so exciting to open each pad and find them sprouting!
I wrote more about this technique in more detail in a Hayefield blog post: The Science of Seed Germination.
Plastic bags with vermiculite or perlite: When germinating large seeds that need a cold-moist or warm-moist period, such as pawpaw (Asimina triloba) and American filbert (Corylus americana), using paper towels can be difficult, so I instead mix them with moistened perlite or vermiculite in a labeled plastic bag (one kind per bag), add a twist-tie, and put them in the refrigerator or a warm place.
Write on the bag or a sticky label so you remember the name of the seeds, the date you put them in the bag, and the date you need to move them to different conditions. I try to check my bagged seeds once a week or so, taking out any seeds that have germinated and potting them up.
Milk jugs: Half-gallon or gallon-sized plastic jugs used for milk and other beverages can be repurposed into outstanding containers for outdoor seed-sowing. I have written about them in more detail in Sowing in Milk Jugs (aka Winter Sowing).