How to start seeds indoors for your spring garden
Q: What is the best way to start seeds indoors? How soon should I be starting seeds indoors for spring planting?
A: To determine when to plant indoors, I recommend counting backwards from the date you plan to plant the seedlings outdoors. Around the Redding area we usually get a killing frost sometime around mid-April, so it’s best to wait to plant until after April 15. Peppers, especially hot peppers, and eggplant are slow to germinate, and grow and can take 10 to 12 weeks to produce a good transplant. Tomatoes take around eight to 10 weeks while other plants such as lettuces, beans, squash and cucumbers grow faster and can be ready for transplanting in as little as three to four weeks.
Here are some tips to successfully start seed indoors.
Always start with sterile growing containers and soil. Seedlings can easily get a soil borne disease called “damping off” that causes the young seedling tissue to rot right at the soil level. This causes the seedling to topple over and die. If you plan to use old pony packs, flats or other recycled containers, clean with warm soapy water then sanitize them by giving them a 30-minute soak in a 10% bleach solution: Nine parts water to one part bleach.
Other containers such as milk cartons, disposable cups and egg cartons can be used, just make sure to punch holes in the bottom.
Other recycled material such as toilet paper, paper towels or gift wrap tubes can also be used for containers if cut in short lengths and placed on end in a flat or large clamshell. These types of containers can be planted directly into the garden bed, and work well for seedlings that do not like their roots disturbed such as squash, beans and melons.
Sterile potting soil is just as important to seedling success as sterile pots. Purchase a good quality potting soil or seed starting mix. Don’t get a soil that has a lot of fertilizer added, as this can cause the new seedling roots to burn.
To plant seeds, fill containers with moist soil and sow two seeds per cell by poking a hole and covering with soil mix. Don’t plant too deeply or tamp soil down. The rule of thumb is to plant seeds to a depth three times the diameter of the seed.
Water seed gently, making sure to wet the entire depth of the container without disturbing the seeds. Next, cover the soil surface with plastic film until the first seedling emerge from the soil. Then remove the plastic cover immediately and move to a spot where the seedlings will get maximum exposure to light.
Light can be provided by using full-spectrum lights, grow lights or LED grow lights. Lights should be kept four inches above seedlings and kept on 14 hours per day. If seedlings don’t get adequate light they will become spindly with soft leggy growth.
To get summer vegetable seeds to germinate you will need to keep the soil at 80 to 85 degrees Fahrenheit until seeds sprout. Many gardeners use heat mats to ensure the soil stays warm enough.
Once seeds germinate, seedlings should be grown at temperatures of 55 to 60 degrees at night, and 65 to 70 degrees during the day.
After seedlings develop a second set of leaves, thin them to one plant per cell or pot. Water only when soil starts to feel a damp sponge. Every couple of weeks apply enough liquid fertilizer so that some drips out of the drain holes in the bottom of the container.
As you near transplant time, get plants ready by hardening off. This is done by slowly introducing them to the wind, cooler temperatures and direct sunlight. Place them outside for lengthening intervals over two weeks. Start with an hour and work up to a full 24-hour cycle.
The Shasta Master Gardeners Program can be reached by phone at 242-2219 or email email@example.com. The gardener office is staffed by volunteers trained by the University of California to answer gardeners' questions using information based on scientific research.