Test your soil for acidity.
Testing your soil for acidity is another important step to take before purchasing seeds. The pH of the soil is a measure of how acidic or alkaline it is. Most plants prefer a mixture that falls in the neutral range (6-7 on the pH scale), but this can vary from plant to plant: azaleas, for example, are more happy in soils with lower pH (more acidic), while grasses and vegetables tend to grow best in slightly higher ones. For most home gardeners, you can figure out if your soil is within range with a simple pH tester, which you can purchase at any home improvement store or gardening supply shop.
If it turns out your soil isn’t within range, don’t worry! There are lots of ways to amend it and bring it back into balance. If your soil is too acidic, you can use lime to bring up the pH level; if it’s too alkaline, sulfur will help lower that scale down again.
Buy a seed-starting mix.
Instead of making your own seed-starting mix, you can save time and buy a pre-made, sterile seedling mix. (Note: Sterile means it’s free of weed seeds, pathogens, and other contaminants that could harm the young plants.) Look for a mix labeled as “seed starter” or “seed starting.”
You can also make your own mixture from ingredients at home. One option is to fill up the cups with an equal amount of vermiculite for drainage and perlite for warmth and aeration. Both are inexpensive, readily available in garden supply stores, and will not compact when mixed with soil. Consider adding fertilizer to your soil (either homemade or store-bought) to ensure the seedlings have adequate nutrients during the first few weeks of their lives.
If you use garden soil, make sure it’s sterile.
You can use garden soil for seed starting; it will be fine, but know that you’re taking a chance. Garden soil is not sterile, and therefore could contain disease pathogens and weed seeds. If you choose to use it, bake it in the oven at 180 degrees Fahrenheit (80 degrees Celsius) for 30 minutes to kill off any infectious agents. Make sure your oven reaches 180 degrees F (80 degrees C); you don’t want to accidentally kill off the nutrients while trying to sterilize the soil! If your oven doesn’t go up that high, buy a thermometer so you can monitor its temperature. When in doubt, heat the soil longer than 30 minutes; pathogen spores are tough little buggers!
If you’re not sure about the quality of the soil, add some fertilizer to help your seeds get started.
If in doubt, add fertilizer. Even soil that looks good on the surface may be deficient in nutrients or have other problems. A small amount of a slow-release fertilizer is often all you need to help your seeds get started. Look for a product that says “slow” or “gradual release” on the label.
Slow-release fertilizers provide nutrients over an extended period of time. They’re usually applied once at the beginning of the growing season, and then they work their magic as needed throughout the season. For example, some types release nutrients as they break down in response to soil moisture or temperature change; others release nutrients if plants need more nourishment (as indicated by leaf color).
Some slow-release fertilizers are organic, such as blood meal, bone meal and feather meal (all made from animal waste), and others are synthetic, such as sulfur-coated urea and polymer coated urea (sometimes called controlled-release nitrogen)
You can grow seeds in a number of different things, depending on your needs and environment.
When you save seeds from plants, it’s helpful to have a good growing medium. A well-drained compost or soil mix will let your seeds grow. And this is where a little bit of science comes in.
Here’s the trick: Soil needs to be porous, which means there are air pockets in it that can give your seedlings water and nutrients as they grow. But if the soil is too wet, those air pockets will collapse, and your seedlings won’t be able to get enough water or nutrients for full growth. Soil also needs enough oxygen content so plants don’t suffocate from lack of oxygen. If you’re planning on planting large quantities of seeds into one container (like a community garden), you might want to consider using a more densely packed mix (like potting soil). However, if you’re just starting out with smaller batches of seeds into one plant container (like an apartment balcony), then using a looser mix is fine and may result in bigger plants once they sprout up some roots and begin spreading their leaves.