Seed Starting

It’s time to break out your seeds and coax them into the land of the living!

Ger·mi·nate: To develop into a plant or individual, as a seed, spore, or bulb. To come into existence; begin.

The best way to give your seeds a jumpstart in the upcoming growing season is to sow them indoors. In such a protected and climate-controlled environment, seeds have the opportunity to develop their root systems before heading outside to play with the big boys. After a bit of intention and groundwork in the indoor sowing process, you’ll observe an earlier blooming of annuals, and perennials that are confident and established in their new spaces. If you live in an area where there isn’t an especially long summer, indoor sowing can help your garden have a stronger and more vibrant summer in its sun-limited conditions. Read your seed packets to check how much time is needed indoors for your seeds; they could require anywhere between 6-12 weeks. 

Gather the materials! You’ll need a germinating mix, a mix created specifically for new seeds to begin; not just potting soil. Select one with finely milled sphagnum peat, vermiculite, or perlite that has no weeds or pathogens. Go with organic mix if you’re growing anything edible. We love Espoma Organic Seed Starter. Mix in a bit of water until it’s the consistency of a wet sponge, and let it absorb for a couple hours (check out this video for seed starter mix expertise!). Assemble containers for your seeds. They’ll need space to grow their roots, absorb air and water, and a drainage hole or two. We love cardboard egg cartons because they will compost in your garden. Eggshells are also compostable and are calcium rich. Stack two broken eggshells together and voila; that’s your container. Try a newspaper wrapped around a can or jar, creating a little cup. Take the can away and you’re left with a compostable cup (here’s how!). If you need a warmer environment for your seeds, try a clean, plastic milk carton with the top cut off. It’s not compostable, but it’s reusable. Last, you’ll need a source of bright light. Try a couple of cool fluorescent bulbs hovering about 16-36 inches above your seeds. You can raise the lights higher as the plants grow taller.

  1. Fill up your containers with seed starting mix, leaving half an inch of space at the top of the container. Rather than packing it in tightly, pour it in and then tap the container to get the mixture to settle.
  2. Your seeds need about four seed-widths between them. If they’re quite small, you can put 4-6 seeds together in one cell of an egg carton. Seeds that are medium-to-large-sized can be put together in groups of 2-3. 
  3. To figure out whether seeds should be covered with soil or exposed to light, look on your packet. If it says “surface sow,” they need light. Gently press them into the mix and sprinkle with a fine dusting of vermiculite. Other seeds, like delphiniums, require darkness and should be covered with the mix and a sheet of black construction paper. 
  4. Water your babies. Gently spray 1-2 times per day so that the seed starting mix is moist, but not dripping. Cover the containers with a clear lid that doesn’t touch the potting mixture; this will create a humid environment. All types of seeds must be kept damp!
  5. Monitor the temperature of the room; keep it between 65-75 degrees Fahrenheit. If the room is cold, utilize a heat mat to raise the temperature. 

A Couple of Pro Tips

Bear in mind that some seeds require cold stratification. This is a period of time where the seed requires cold and moisture in order to break embryonic dormancy. If your seed packet suggests a cool temperature, sow these seeds either indoors in moistened flats with covers, or place the seeds between damp paper towels in sealed plastic bags and put them in the fridge. Make sure they don’t dry out or freeze. Alternatively, if you’d like to sow these seeds outdoors, do it in early spring or fall so they will naturally experience that cold, wet process. 

Sweet peas and other seeds with hard coats benefit from being nicked (fingernail clippers applied to the edge, or lightly scrubbing with sandpaper) and/or soaked in water for 8-12 hours in the germination process. 

After several weeks of regular watering and temperature monitoring, you’ll observe sprouts where you once buried seeds. Success! Your seeds have germinated, and it’s time to change up the routine. Take off the lid, lower the temp of the room by about ten degrees, and bring the light source 2-4 inches away from sprouts. Prepare to monitor moisture levels even more closely; your seedlings’ root systems are very fragile. In your watering routine, switch to watering seedlings from the bottom. Watering about once per day should be sufficient. If your soil is damp and cool to the touch, it is healthy, but if it is dry, it needs more water. If using permeable containers, dunk them in a tray of water until you see the potting mix darken slightly. Take them out and place them on top of a cooling rack or some kind of tray that allows aeration. This will bring a balance of moisture, with the cardboard holding just enough water in its strata. If not using permeable containers, water from the top as you did during germination.

To determine whether it’s time to transfer your plants outside, check the growing zone for your area and count backwards from any estimated last frost dates. It’s essential to ease into the transition because the cellular walls of the seedlings are still gaining strength. Stay tuned for our next blog post on hardening off.

Seed you later!
My Thyme Gardens

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