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Seed Starting: Why and How to Get Your Planting Started Indoors
Should You Even Bother??
It's not that easy to germinate a seed. We have to wait for the ground to dry up and the sun to start shining to really take full advantage of the garden here in the Pacific Northwest. But no matter the weather, starting seeds can accelerate the process of growing in any conditions.
Why Start Seeds at Home?
1. Season Extension: Starting seeds indoors extends your growing season. When you start seeds in advance of their sow dates, you gain a head start by planting before you can plant outdoors in garden beds (aka “direct sow”), and this extra time means you’ll be harvesting earlier.
2. Freedom: When buying seed, you can experiment with lesser-known varieties and harvest something new each year.
3. Economy: It's economical to buy seeds—one pack of lettuce will have you in salad for a year (a year!) and costs about the same as one 4-inch pot of starts. (This is how I started growing food, by the way, as a poor 20-something who wanted to eat local.)
Many beginners trust that a sunny windowsill will receive enough light to grow plants. This is not always true, most especially in winter. Most apartments and many houses don’t have perfect growing conditions and will need some supplies to mimic them.
• Light - Seeds can be started in ordinary indoor light, but once they push up out of the soil, the seedlings need up to 12 hours of daily light to grow vigorously. In the northern hemisphere, we don’t see that sort of natural light until well after the first day of spring. But with the aid of grow lights, you can provide enough supplemental indoor light to convince seeds and seedlings that they’re out in the sun.
Grow lights can be picked up at most local hardware stores and plant shops.
• Warmth and Moisture - Plastic seed trays are made from thin black plastic and have small cells to hold soil and seed. Be sure to also purchase the clear plastic cover that fits over each tray. It acts as insulation to keep seeds warm and moist, the perfect condition for germination. You will also need the plastic liner for your seedling tray to sit in. This liner will catch and retain any excess water that drains, sparing spillage and helping to keep seedlings moist. (Here, I’m using a styrofoam seed cell, which I prefer because I can start over 100 seeds at once.)
• Seed Mix - The trays should be filled with a sterile seed-starting mix—which technically is not a soil. These mixes allow for good drainage, air circulation, and absorption and retention of water. There are no nutrients added to sterile seed mixes—new plants don't need them to start, as each seed has a small amount of food supply for the plant’s early growth! You will eventually need to fertilize.
Seed Mix Recipe
If you’d like to make your own seed mix, follow this recipe comes compliments of Growing Vegetables West of the Cascades, by Steve Solomon and includes fertilizer:
1 part by volume garden soil
1/2 part by volume finely screened compost
1/2 part by volume sifted and premoistened sphagnum moss
Into each 5 gallons of seed mix, add 2 cups organic fertilizer & 1/2 cup agricultural lime
• Placement - I set up seed trays on my dining room table in front of my only window—one that faces due east. Any table will do; just be certain you can plug in a grow light nearby. Place trays as close to natural light as possible, and rotate them every few days so plants will not stretch for the light and grow too leggy.
Step by Step
Once you have your seeds, tray, grow light, seed-starting mix, and a dedicated space to grow in, it’s time to start planting.
• Cover your work surface with newspaper to catch any messes, and fill the seed tray about three quarters of the way full with the mix. (You will be adding a bit more later to cover the sown seeds.)
• Using a small bottle, gently water the entire seed tray, making sure the mix gets thoroughly dampened. It’s important to moisten the mix now so it will absorb the moisture and get weighed down. If you do this AFTER you’ve sown your seeds, the water will pool on the surface of the mix and seeds can easily spill up and over the sides of the plant cells.
• Sow 1 to 2 seeds in each cell of the tray, working in rows. I suggest planting only one variety of seed per row, even if you don’t fill the row. This will help keep things organized. Label your seeds as you go—you'll thank me later.
• Lightly cover the entire surface with another sprinkle of seed-starting mix, and water very lightly again. As the bottom layer of mix is already moist, the top layer needs only a trickle.
• Cover the tray with the clear plastic top and slightly prop up one corner with a bottle cap or similar item for a bit of ventilation.
• Set the tray directly under your grow light, and set it to shine for 12 hours. Typically, I time the grow light to run from 6 AM to 6 PM to make the most of natural daylight.
Now that your seeds are planted, always keep the top layer of the mix just moist (not wet), never letting it dry out. The clear plastic cover will collect moisture from condensing evaporation. If there is no condensation on the plastic cover, that is usually a good indicator that you need to mist the tray with more water.
When seedlings are tall enough to hit the sides of the plastic cover, remove it and harden them off before transplanting your seedlings into a garden bed or pot.