Starting plants from seed can be an economical way to grow a garden and is a very rewarding experience. There are several advantages to growing plants from seed:
- Access to a wide selection of varieties
- Stronger plants that have not had the shock of transplanting
- The ability to use seed that was collected and stored from previous years, passed from neighbor to neighbor, or shipped from other regions
In early spring, many gardeners have small seed trays lining their windowsills, kitchen counters, and/or tabletops. Indoor seed starting requires bright light, adequate moisture, high humidity, and a watchful eye. Placing a clear plastic dome cover over your seedlings will help hold in moisture and humidity. Bottom heat from a seedling heat mat can speed up the germination process (when the seed cracks open and begins to grow), but is not necessary for success. Be sure to remove the plastic dome and heat mat as soon as seeds have germinated.
If indoor gardening is not for you, it is easy to grow from seed outdoors by sowing directly into the garden soil, but it is important to consider the soil temperature and how it may affect germination. A soil thermometer is a simple tool used to take the earth’s temperature; it can greatly improve your seeding and transplanting results by planting at the safe and proper soil temperature.
As soon as soil temperatures are in the 40s in my garden, I can sow pea seeds and plant potatoes; I will continue to monitor the soil warmth and plant my crops as things heat up. There are many crops that can be planted when the soil has reached at least 40 degrees such as beets, broccoli, cabbage, carrots, cauliflower, celery, chard, endive, lettuce, onion, parsley, parsnip, peas, radish, and spinach, to name a few.
Check seed packet for details; may say “plant indoors 6–8 weeks before last frost.” Average last frost date for Portland metro area is April 15th.
Bright light is essential; a sunny east or south-facing window (supplement with fluorescent full-spectrum or LED light bulb); check out our new Jump Start grow light system for seedlings.
It’s best to use sterile seed-starting mix, jiffy pots of dehydrated coir, or coir bricks (if using seed-starting mix, I like to pre-moisten soil before planting); ideal to use biodegradable pots that can be directly planted in the ground such as peat pots, newspaper pots, or even egg shells.
Keep seed bed thoroughly wet, water gently and consistently; solid bottom trays and humidity domes help to maintain moisture (be sure to remove humidity dome after seeds have germinated); a spray bottle is handy too.
Check seed packet details; can take several days or several weeks depending on type of seed planted; adding a heat mat under your seedling trays can greatly speed up germination, but heat should be removed after seeds have sprouted.
- Most seed is good for at least 3 years (larger seeds such as corn may not last as long); if using old seed, it is wise to do a germination test before mass planting
- Choose items with multiple harvest potential: leafy greens, lettuce, salad mixes, leafy herbs like basil, cilantro, or parsley
- Remember to mark your seeds with labels; plant 2-3 seeds per pot
- Recognize first set of leaves versus “true” set of leaves: the first ‘leaves’ to appear are called the cotyledon and are the embryonic first leaves of a seedling; after the cotyledon the seedling produces its first set of “true” leaves that more closely resemble the adult plant
- Planting depth depends on seed type (check packet info); good rule of thumb is 3 times as deep as the seed is wide; better to plant too shallowly than to be too deep
- Some seeds (especially large, hard-shelled ones) benefit from soaking in water overnight or for up to 24 hours before planting (e.g. garden peas)
G&B Organics All Purpose liquid fertilizer (3-2-3) diluted to ½ or ¼ strength is best to feed seedlings weekly or every 10 days once seeds have germinated and grown their first set of ‘true’ leaves.
Transplanting & Hardening Off
- Best to wait for second or third set of ‘true’ leaves before transplanting
- Check plant info/seed packet for best time to plant outside (check soil temperature with a soil thermometer; pay attention to nighttime temperature lows)
Seeds at Dennis’ 7 Dees
Stop in and visit one of our garden centers to see what seeds we have in stock, as well as our great selection of supplies necessary to get you growing! We carry 2 great seed companies::
Territorial Seed Company
Territorial Seed Company is a family-owned business since 1979 from Cottage Grove, Oregon. They carry certified organic, biodynamic, and heirloom seed varieties. They have 44 acres of trial grounds at London Springs, south of Cottage Grove Lake. Each year, Territorial’s research garden staff grows and evaluates thousands of varieties for best taste, Northwest hardiness, and good germination.
Since 1995, Botanical Interests has been supplying gardeners with the highest quality seed in beautiful and informative seed packets. Their desire to provide more information led them to create a unique seed packet that includes art, garden history, landscape ideas, organic gardening know-how, recipes, fun facts, and high-quality seed.