It’s Not Too Late to Start Seeds Indoors for Spring Planting

By Kathy Hansen, WSU Extension Master Gardener, Stevens County


Perhaps one of the reasons Pacific Northwesterners so value their gardens is that our growing season is so short; we want to make the most of our time in our gardens and get the best yield from them. One way gardeners here stretch the season is by starting seeds indoors while the ground is too cold for planting. It’s not too late to start seeds for 2021!


The first step is to determine when to start each type of seed inside so it can be transplanted after the danger of frost is over. Various calculators, such as this one at the Dave’s Garden site – – are available to let you know when the last frost is likely. For Loon Lake, May 16 is listed as the last-frost day. You can then consult the Annual Seeding Schedule for this area, prepared by the Spokane WSU Extension Master Gardener Program for the amount of time before that date that each plant needs for germination at


Next, gather your supplies. As garden writer Kate Bryant notes, almost anything that can hold about a three-fourth cup of soil can work as a container for planting seeds. In the accompanying photo by Master Gardener Mary Sety, containers are made of newspaper. Be sure to scrub and sanitize any pots or containers you’re reusing. You’ll also need dishes or trays under the containers to hold excess water, soil (more on this in a bit), and labels to help you distinguish seedlings that may all look similar early on. It’s also a good idea to note the planting date on labels.


Bryant describes artificial lighting as “valuable – but not completely essential.” Natural light from windows may be sufficient, though Bryant says grow lights are more reliable. Fluorescent shop lights like those Sety used in the accompanying photo also work well. Most seeds don’t need light on them until they germinate. Another non-essential, but nice-to-have, item is a heat mat for plants like eggplants, peppers, and tomatoes that like bottom heat. You’ll also, of course, need seeds.


Now, about that soil. Blogger Erica (no last name given) of Northwest Edible Life notes that while a sterile potting mix is important, the “obsession with seed-starting mixes specifically is a bit silly.” A joint Extension publication from Washington, Oregon, and Idaho, “Propagating Plants from Seed,” describes how to make your own “germination media,” by mixing two parts garden soil, one part peat or coir fiber, and one part medium to coarse sand.” To sanitize, the WSU Extension advises, “heat the mix in a shallow metal tray or wooden flat” for 30–40 minutes at 140°F–150°F.


Sow your seeds according to instructions on the seed packets. Erica suggests keeping light on seedlings, once germinated, for about 16 hours a day. Moisten the planting mix after sowing by placing containers in a pan, tray, or tub of about 1 inch of water, advise the authors of “Propagating Plants from Seed.” Once the soil surface is wet, set the container aside to drain for an hour or two. Monitor the moisture level as the seeds germinate and be careful not to over-water.



The joint Extension publication “Propagating Plants from Seed” is a comprehensive guide to seed-starting in the Pacific Northwest and can be found at
Annual Seeding Schedule, Spokane WSU Extension Master Gardener Program.
Seed Starting 101: A Step-By-Step Visual Guide to Growing Seedlings at Home, by Erica.
Indoor Seed-Starting, by Kate Bryant.


The WSU Extension Master Gardener Program trains volunteers to be effective community educators in gardening and environmental stewardship. Master Gardeners provide information generated from research at WSU and other university systems.


Kathy Hansen is an educator, writer, social-media junkie, career practitioner, and 5-star short-term rental superhost at Hansen Woodland Farm ( in Kettle Falls.