Seedlings Not Developing? Here Are Potential Causes
Sometimes seeds will sprout and the seedlings will chug along for a while and then seem to stop growing. Here are possible reasons why, and what to do:
Seedlings not developing because conditions are too cold. Seedlings of heat-loving plants (such as coleus, zinnias and peppers) may stall if the air temperature is not warm enough. Boost the heat or move your seedling setup to a warmer room. Or bide your time and they will likely accelerate as the days lengthen and temperatures rise.
Seedlings not developing because of too much competition. If you have several seedlings to a pot or cell, they may be growing slowly (or not at all) because there’s not enough resources to go around. Cull the seedlings to one per growing unit by snipping the extras off at the soil line. Alternatively, transplant each seedling to its own larger container.
Seedlings not developing because of lack of nutrients. Seed-starting mixes are usually not fertile enough to support continued seedling growth. Transplant your seedlings into a nutrient-rich potting mix.
Seedlings not developing because they’ve outgrown their container. Even if your seedlings are in a rich growing medium and they each have their own pot, they may stall if they’ve grown too big for that container. Gently tip them out to inspect the roots; if there’s a crowded mass of roots (possibly taking on the shape of the container) it’s time to move to a bigger pot. Seed-starting mixes are usually not fertile enough to support continued seedling growth. Transplant your seedlings into a nutrient-rich potting mix.
Reuse Coffee Pods as Seed-starting Pots
Single-serve coffee brewers are convenient, but the used plastic brew cups seem so wasteful. We’ve heard of gardeners giving these pods a second use: seed-starting containers.
We haven’t tried it ourselves, but a single-serve coffee pod is a good size for starting a single seed (or sowing several seeds and culling the seedlings down to one). The pod already has a drainage hole, thanks to the brewing machine. All that’s left to do is remove the foil top of the pod, clean it out, fill it with seed-starting mix and proceed as you would with any seed-starting vessel. (That said, one gardener even reports sowing seeds into the used coffee grounds or tea leaves, rather than replacing them with seed-starting mix first.)