Why Germination Conditions Matter
Why Start Plants from Seed?
I’ve mentioned before that I’m interested in integrating as many permaculture principles into my lifestyle as possible. Agriculture based on permaculture principles should mimic the natural world as much as possible – and natural ecosystems typically include diversity of both species and genetics. Starting plants from seed is not only more economical than purchasing young plants, but it also allows for more genetic diversity (at least with open pollinated species). Knowing what factors could be an issue is the first step to troubleshooting difficult to germinate species.
This one seems obvious but there is more to it than you might think. Seedlings generally need to be kept moist but not wet. This water should also (ideally) be chlorine-free. Urban water supplies are heavily chlorinated, so I let my water stand on the counter for at least 24 hours before I use it to water my seedlings. Also, if seeds are allowed to dry out after they have initially been wet some species will enter a second dormancy that is much harder to break!
This often-neglected factor is actually very important! Most seeds will not germinate in saturated (waterlogged) soil. Seeds and the seedlings they produce need to breath just like we do, so drainage in seed trays is very important!
You might have expected me to say “soil” here, but seedlings actually don’t need soil per-say. Soil, by definition of the NRCS, is “The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants.” Soil is a limited resource, and it is not the only option.
Seedlings need a substrate to germinate in but that substrate can be partially-decomposed plant matter (such as peat moss or compost), minerals (such as vermiculite or perlite), a combination of these (found in many soilless growing mixes), or just about anything that gives seedlings the structure they need. Generally things to consider when choosing a germination substrate are:
- pH: Without going into too much chemistry, pH is a measure of the acidity or alkalinity of a substance. Soil is acidic at pH levels under 7 and alkaline at pH levels greater than 7. Soil pH also affects the availability of nutrients and minerals needed for plant growth. Most seedlings will grow in slightly acidic soil (pH around 6), but some species (blueberries, parsley, potatoes) prefer much more acidic conditions. A few species (asparagus, leeks, marjoram) prefer alkaline soils.
- Texture: The size of the substrate particles affects how uniformly moist the seeds are kept. Finer particle sizes will keep seeds evenly moist. A coarse substrate will not retain moisture well enough to be a good germination substrate for most seeds.
- Compaction: Substrates that are more compact will generally keep seeds more evenly moist. Soils that are overly compacted (such as soils that are frequently driven over by a tractor) will be too compact. Some pore space in the substrate is necessary to make sure the seeds do not become waterlogged and to make sure seedling roots can penetrate the substrate. However, too much pore space means that the substrate will dry out too quickly.