The tried and true gardener keeps busy all year, but early spring ignites in us the desire to start sprouting. Just thinking about all the kale and lettuce I can have at my fingertips motivates me to get growing! Whether you are sprouting in a greenhouse or your kitchen windowsill, a steady light source is helpful, especially when used with a seedling heat mat. If you don’t have a seedling heat mat, don’t worry, they are readily available in garden centers and online. I’ve had questions from clients about substituting heating pads for heat mats or paper cups for seedling containers. Ideally, you would buy the proper components – a heat mat isn’t intended for seedlings and can be a fire hazard, not-to-mention dry out your seeds too quickly. Paper cups often have wax in them and otherwise disintegrate quickly. A seedling mat on Amazon starts around $20 (and lasts years) and the containers can be recycled and used year after year, so consider investing.
As always there are a few steps to prep before the actual process of sowing those seeds.
Here are a few tips to get started:
Are you using recycled pots or containers? It’s a great idea to wash them (a bleach-and-water solution works well to prevent the spread of disease). Additionally, it’s always a smart idea to have them all organized by size.
Take account of seeds on hand — often times last years seed will sprout. Want to test them out first? There’s a trick for that!
The size of your seeds can tell you how big a container to start them in. Small seeds like lettuce, tomatoes, basil, and the lavender shown above benefit from a start in a smaller container like a small celled 6 pack. You can also use a grower flat with good drainage that you can sow into and thin the starts out of. Larger seeds like sunflower or squash can easily sprout in a large cell 6 pack or 4 inch pot and larger.
It’s helpful to fill the containers 2/3 full with a potting soil that has good drainage like Lane Forest’s Lane Potting Mix; moisten the soil to be sure it settles. Next, sow seeds on to the moistened soil and top off with more soil and water. A delicate mist is best for seedlings, although a small size watering can is fine too. Once your plant is thriving, it’s time to take them off the baby food and graduate to nutrient-rich soil. (Note: some more delicate seedlings require sphagnum peat moss and are fussier than your average stout seed).
To heat or not to heat?
I’ve found that the size of the seed can also determine whether it would benefit from the bottom heat source or not. Starting seeds in mid – February temperatures, the extra heat is crucial for the survival of many small seeds. I start lettuce and kale seeds on a heat mat under 12 hours of lights. I tend to wait until March to start large seeds like squash and sunflowers so they are not too early for the garden party. These I do on my greenhouse shelves with no extra light or heat. The warmer days and stable nighttime temperatures are just fine to get these sprouting.
Even moisture is key in keeping seedlings alive. Greenhouses and heat mats cause them to dry out quickly, so it’s helpful to mist them 2-3 times a day. Upon planting, a high nitrogen fertilizer (like fish emulsion) or a dose of vitamin B-1 with seaweed can provide a food source for sprouting seeds. Following up once a week with a dose of liquid love is a good regimen to follow.
Written by Oregon landscaper and longtime Lane Forest Products customer: Heidi Branchesi of Heidi’s Timely Gardening Tips. Keep in touch with Heidi and all of her wonderful gardening advice in our Expert Advice section and on her Facebook page.