Starting seeds is one of my favorite things to do as a farmer. I admit I'm a seed hoarder-- I can never say no to more seeds and often end up with way more than I can plant. Seed catalogs can entertain me for hours, and the packets get strewn about the living room (and any flat space) for extended periods of time.
Seeds fascinate me; each has its own incredible potential. Beautifully diverse and interesting, seeds contain a perfect package for starting new life as a baby plant. Although you can start seeds inside whenever you want, we start the majority of our seedlings in the spring because that is when the temperatures rise enough for seeds to germinate and the plants have enough time to complete their life cycle.
Here are some of my own methods and neat tricks that I have learned, both from wise friends and at the recent Oregon Small Farms Conference.
Seeds germinate when the right conditions are met, namely, temperature and humidity (with some exceptions such as light, scarification, or cold stratification described below). Thus, it is quite easy to sprout seeds in your house in small containers, as most will germinate when between 50-75 degrees. (Some plants like it really warm to germinate, such as tomatoes, peppers, and eggplants, in which you will need to use a heat mat or a particularly warm spot.) You can even germinate seeds without soil in jars (as this is often how people make edible sprouts) or in moist paper towels (or coffee filters). The pro's use a germination station, which is usually a large insulated box with many tray shelves and a heating and humidity monitoring system. I've seen farmers use an old freezer or fridge with a crock pot filled with water at the bottom. Just make sure that when the seeds have germinated, they get outside with enough light to grow!
Quick Germination Test
Sprouting on paper towels makes for a quick and easy germination test and will let you know your % germination if you are using older seeds. To do this, take 10 seeds and place them inside a folded paper towel or filter, add some water so that the paper and seeds are moist, and place them in a plastic Ziploc bag. Observe the seeds for several days, and most will sprout within a week. You can easily calculate the % of seeds germinating now and can use that number when doing more seeding. You can transfer the germinated seeds into a container of soil.
Special Germination Requirements
Although most vegetable and flower seeds will germinate if moist and at the right temperature, some seeds will do much better or may only germinate once very specific conditions are met. These details should be found on the seed packet.
-Light: Light exposure is important for some flower seeds and lettuce. This usually means you do not cover them with soil-- just press them lightly into the medium. Seeds that benefit from light include snapdragons, columbine, and poppies.
-Scarification: Some seed coats (the outer protective layer of the seed) are tougher than others and can use some help to access water. To do this, you can use sandpaper, nick them with a file, or just soak for 12-24 h prior to planting (I like this last method). Seeds that benefit from scarification include cilantro, nasturtiums, milkweed, and lupine.
-Cold stratification: Perennials often need to "experience winter" temperatures before they can become ready to germinate. This can be don by sowing in fall, leaving pots outside for the winter, or simply putting the seed packets in the fridge for several weeks (I prefer the latter). Seeds that benefit from cold stratification include milkweed, lavender, and sedum.
Seed Starting Soil Mix
If using soil, it is important to start with soil that seeds can easily germinate in. This usually means it needs good drainage, has a fine texture, and correct pH. Because seeds do not need any fertilization to germinate, extra nutrients are not necessary (although its good to have once they become sprouts.) You can buy seed starting mix or make your own. I bought the Black Gold mix, which is basically just peat moss and perlite. However, I noticed that my seedlings did a lot better when I made my own, which included compost and a small amount of natural fertilizer (fish, kelp, feathermeal, seedmeal, etc.). Here is my recipe, inspired from Eliott Coleman's recipe and one found on the website patchesofgreen.com. The numbers can be any units, as long as you keep the ratio the same.
Pots, Trays, and Blocks
I use whatever containers I have, although a few things make it a lot easier. Trays can come in various sizes, but allow you to plant a large amount of seedlings and keep them together easily. I start my regular seeds in trays or seed blocks, and if necessary, I pot them up to a bigger pot when they grow too large. Sometimes I will start many seeds from an older packet into one container, and then transfer each baby seedling into a tray or pot. Most seeds are safe to transplant after they have four true leaves. Make sure you water them before transplanting.
Seed blocks are fun and do not use plastic. I purchased mine (4 blocks of 2") on Amazon for about $30. Because they have no physical sides, the plants can't get root bound (twisted up inside the pot) and therefore transplant better. I use the seedling mix stated previously to make the blocks. It's a bit tricky to get the right moisture content, but once you figure it out you can make them quickly and efficiently.
Seeds can be easily kept viable at room temperature for many years. If you've purchased seeds, you can also store them in the refrigerator or freezer for longer term storage, although the seeds must be completely dry. Most seeds will last many years. In fact, most farmers buy seeds to last for three years (except for alliums, which don't last as long). Consider this before you throw out your old seeds and if you plan to plant some of the same things every year. Buying in bulk is usually a lot cheaper!
Happy seed sprouting and good luck! We will be selling some of our left over plants in the farm store, so stay tuned.