Seed Starting

Getting Started

Browse seed catalogs for varieties not readily available at your local garden center. Consult fellow gardeners about seeds you can share – there are usually more than 30 seeds in one package (sometimes hundreds), except for the rare, new species, which may have only five or 10 carefully-counted seeds.

Make a list of what you’d like to plant. Don’t plant too much; every seedling will need to be planted in a larger container before spring, and eventually planted in the garden. Sketch your garden’s dimensions on quad ruled paper, where 1/4” = 1’. (If your garden is small, you can sketch it out to 1/2” = 1’.) Draw circles to represent the mature size of your selected plants and to help determine how much space you have to work with. From there, you can prioritize your planting list. Remember, tomato seedlings grow into large tomato plants and if you overcrowd them, they will become thin and spindly, producing little fruit.

Timing Is Everything

Plan your planting timetable. If you live in a climate with four seasons, check your area’s frost-free date. Consult seed packets, a seed catalog or the Internet to determine how many weeks it will take for the seeds to grow into viable seedlings ready for transplanting in the garden. Subtract this amount of time from the frost-free date by counting backwards.

Hardening off entails setting the plants outside in a protected area before planting to acclimatize the indoor-grown seedlings to the harsher outdoor conditions. They should be placed in a shaded, protected area and gradually left out for longer periods each day. Allow about two weeks for the hardening off process.

Sow your seeds with the assumption that weather conditions will be favorable by the frost-free date and, if necessary, alter your planting schedule. For example, the frost-free date where I live is May 19. If by that time the weather is unstable and there’s still some frost, I’ll likely wait an extra week or two before transplanting. Seedlings planted in cold soil may not thrive; wait a few weeks and plant them in warmer soil.

Remember, some cool-weather spring annual seeds such as pansies and snapdragons can be started early and transplanted two to four weeks before the frost-free date (provided they have been hardened off properly).

Containers

You will need clean, sterilized pots or seeding trays, washed in soap and hot water and rinsed in a weak bleach solution to eradicate last season’s bugs and diseases. You can also use pots made of peat moss, fiber or coir (a biodegradable alternative made from coconut husk fibers), and plant them right into your garden soil in the spring. If using pots, they should be placed on a tray. You’ll need clear tray covers, which you can buy or make using plastic wrap.

Planting Medium

It’s important to use sterile seeding medium, as you don’t want any weed seeds competing with your selected seeds. You can purchase soilless seeding mix containing peat moss, perlite and vermiculite or you can make your own using sterilized, bagged planting soil mixed with equal parts perlite, vermiculite and sterilized coarse sand. Add warm water until the mix is moist enough to squeeze into a ball that easily breaks apart.

Place the medium into the clean containers and tap the containers on a hard surface to settle the mix slightly. The medium should be somewhat loose so the new roots can extend through it easily. Cover the seeds with vermiculite, which is light, doesn’t compact and retains moisture well.

Seed Preparation

Left: Basil seeds out of the packet. Right: The same seeds after soaking have developed a gelatinous coating.

Follow the seed packet directions carefully. Before sowing, some seeds need to be cooled in the refrigerator, some do better after being presoaked in water for 24 hours, some need to be covered and kept in the dark and some need exposure to light. If your packet doesn’t offer much information, you can always check a reputable Internet source.

I presoak all my seeds, even the tiniest ones, such as basil and parsley. I find the presoaked seeds germinate faster and more reliably. However, never let the seeds sit in water for longer than 24 hours; they sometimes start to ferment and smell (especially snow or snap peas).

Seed Sowing

Carefully place the prepared seeds on the growing medium in the containers. You can use seed planter sticks that have tiny cups at each end large enough to hold one seed. I prefer using an old, dull, pointed knife to pick up each wet seed and drop it onto the planting medium. When I use seeding trays with sections approximately 2” square, I usually plant no more than four small seeds (basil, parsley or tomato) or one large seed (snow pea). Evenly space the seeds. This can be tedious, but I prefer careful planting to thinning out dozens of seedlings that have grown together.

Cover with fine vermiculite and dampen the growing medium using a spray mister to ensure the seeds don’t move around during watering. Cover the tray with plastic to keep the soil moist – if the seeds dry out, they won’t germinate. I place toothpicks at the corners of the pots and stretch plastic wrap, which is inexpensive and effective, over the whole tray.

Place the seed tray in a warm spot, such as on top of the refrigerator. Remove the plastic for a short time each day – you don't want mold and mildew to develop in the pots. When more than 50% of the seeds are showing green growth, remove the plastic and move the tray to the light.

Watering and Lighting

Use tepid water poured into the bottom of the tray. Watering from the bottom ensures that your seeds stay where you placed them in the pot and encourages the seedling roots to grow down to the bottom of the containers, resulting in stronger plants that won’t dry out as quickly.

Full-spectrum grow lighting will help the seedlings grow short, strong stems instead of long, thin, spindly stems striving to reach the light. Grow lights with double rows of fluorescent bulbs emit the best light for new seedlings; they should be kept on for approximately 12 hours each day. A lighting timer is convenient if you’re forgetful.

Keep the temperature lower while seedlings are under the grow lights, to help prevent the plants from growing too tall and spindly. Once the seedlings have their true leaves (second set of leaves), they should be transplanted into individual containers.

So, if you’re still daydreaming about spring and your hands are still nice and clean, better get growing!

Gabriele Davies

Landscape Designer and Horticulturalist