Seed Starting & the Benefits
Question: How does one start seeds? What are the benefits of doing so?
Learning about seed starting beforehand will make it easier and more successful! The proper time for starting seeds depends whether you start seeds outdoors or indoors, as described below.
One of the many benefits of growing plants from seeds is getting a jump on the gardening season in regions with shorter growing seasons, or in warm regions before the summer heat starts to stifle growth. Another benefit is the cost. If you want to grow a lot of plants, buying packs of seeds is usually cheaper than buying individual transplants from the nursery. As well, the selection of plants at local nurseries can be limited, so planting from seed affords a much wider choice of plant varieties.
With the right light and some simple equipment, it’s easy to grow plants from seed to harvest. Below you will find what you should know about starting seeds, including when to do it, which seeds to start indoors (or outdoors), and how to do it correctly. For even more info, read the VCE publication “Plant Propagation from Seed.”
1. Choosing seeds
Quality plants start with good seed from a reliable source (e.g., local nursery, dealer or seed exchange). Choose varieties adapted to your area which will reach maturity before an early frost. Many new vegetable and flower varieties are hybrids, which cost a little more than open pollinated types. However, hybrid plants usually have more vigor, more uniformity, and better production than non-hybrids and sometimes have specific disease resistance or other unique cultural characteristics.
2. When to start
The goal with seed starting indoors is to have your seedlings ready to go outside when the weather is favorable. The seed packet should tell you when to start seeds inside. Usually, it will say something like, “Plant inside six to eight weeks before last frost.” The timing varies from 4 to 12 weeks before transplanting, depending on the speed of germination, rate of growth, and the care of the seeds as they grow. Some types of vegetable seeds, such as beans and squash, are best started outdoors when all danger of frost has passed, and the soil has warmed. These seeds are usually marked “direct sow”. There is little benefit to growing these indoors because they germinate and grow quickly.
3. Equipment needs (container, potting soil, fertilizer, labels)
- Containers – You can start seeds in almost any type of container, as long as it’s at least 2-3″ deep and has some drainage holes. Seeding trays made especially for seed starting are convenient and easier to carry but if you are the DIY type, you might want to grow seedlings in yogurt cups, milk cartons or paper cups, etc.
- Planting medium – Choose a planting medium that’s made for growing seedlings. Do not use soil from your garden or re-use potting soil from your houseplants because it could contain fungal spores or other diseases. Start with a fresh, sterile mix that will ensure healthy, disease-free seedlings. Before filling your containers, use a bucket or tub to moisten the planting mix about as wet as a wrung out sponge. Fill the containers and pack the soil to eliminate air gaps but not too firm as to compact it.
- Labels – There’s nothing more frustrating than forgetting what you planted and when you planted it. Always write the plant name and date of when you planted the seedlings.
When choosing which seeds to plant, choose the largest seeds in the packet for the best chance at germination. Plant the seeds in the moistened potting mix at the depth listed on the seed packet. Planting two seeds per cell (or pot) gives you a better chance for germination. If both seeds germinate, snip one and let the other grow. Moisten the newly planted seeds being careful not to dislodge them. To speed up germination, cover the pots with plastic wrap or a plastic dome that fits over the seed-starting tray. This helps keep the seeds moist before they germinate. If using plastic wrap, poke a few holes in the plastic with a toothpick for ventilation and to prevent mold. When seedlings start to appear, remove the covering and move containers to a bright window or under grow lights.
To start seeds indoors, it is important to have enough light. If you do not have a sunny room or back porch with a south-facing exposure, you will probably need supplemental lights. A simple, fluorescent shop light with one warm-white and one cool-white bulb (or grow lights) will suffice. If you’re growing under lights, adjust them so they’re just a few inches above the tops of the seedlings and set the lights on a timer for 15 hours a day and remember to raise it a few inches above the tallest seedling every couple of days. Keep in mind that seedlings need darkness, too, so they can rest. If seedlings are kept next to a window, rotate the containers to keep the seedlings growing evenly.
6. Water, feed, repeat
Water newly started seeds carefully. A blast of water can dislodge the seeds or young seedlings’ fragile roots. A mist sprayer is gentle but can take a long time. Using a meat-basting syringe (aka “turkey baster”) will dispense the water effectively without causing too much soil disruption. Remember to feed the seedlings regularly with liquid fertilizer, mixed at the rate recommended on the package.
7. Hardening off and planting
Seedlings need a gradual transition to the outdoors. This process is called “hardening off”. About a week before you plan to plant the seedlings in the garden, place them in a protected spot outdoors (partly shaded, out of the wind) for a few hours each day, bringing them in at night, and gradually expose them to more and more sunshine and wind. Keep the soil moist at all times during this period. Dry air and spring breezes can result in rapid transpiration.
8. Transplanting to the garden
After the hardening-off period, your seedlings are ready for transplanting. It is best to transplant on overcast days or in the early morning, when the sun won’t be too harsh. Set transplants into loose, well-aerated soil. Soak the soil around new seedlings immediately after transplanting. Spread a light layer of mulch to reduce soil moisture loss and to control weeds. To ensure the availability of phosphorus in the root zone of new transplants (phosphorus promotes strong root development), mix 2 tablespoons of a 15-30-15 starter fertilizer into a gallon of water (1 tablespoon for vining crops such as melons and cucumbers), and give each seedling a cup of the solution after transplanting.
9. Troubleshooting Problems With Seedlings
- Some or all seeds are not germinating – There are a number of factors that affect seed germination. First, check the seed packet to determine the days to germination (some seeds take weeks to germinate while others take only a few days), and whether the requirements for temperature and light were met. If the seeds are old, they may no longer be viable. If the seeds have rotted from the soil being too wet, they will be swollen and soft. If the soil was too dry, the seeds may have dried up before their roots could take hold.
- Seedlings are spindly – Plants grow tall and leggy when they do not receive enough light. They need about 15 hours of bright light each day plus a rest period. A convenient solution is to use grow lights with a timer. Warm temperatures can also stimulate leggy growth, so try lowering the room temperature. Too much fertilizer can lead to sudden plant growth so reducing the amount of fertilizer you apply can help.
- Mold growing on the soil surface – Mold is an indication that the soil is too wet. Gently scrape the mold off the soil and withhold water for a few days. Increase air circulation by using a small fan. If it continues to be a problem, try carefully transplanting the seedlings into fresh soil.
“Gardening While Isolated: Starting Your Garden from Seeds,” Chris Curry & Kathleen Delate, Iowa State University, Extension and Outreach, April 23, 2020.
“Plant Propagation from Seed,” Elizabeth Ball & Diane Relf, Virginia Cooperative Extension, Publication 426-001, 2019.
“Seed For The Garden,” Alan McDaniel & Diane Relf, Revised by John Freeborn, Virginia Cooperative Extension, Publication 426-316, 2015.