10 Best Tips for Starting Seed Indoors

When to fertilize seedlings

Is seed starting somewhat of a mystery? Are there too many techniques to keep track of and to test? Because there are as many seed starting methods as there are seeds, we thought we would share exactly how we start seeds at Home Grown Fun. This is not a generic post. Not everyone will agree with our process. But we’ve found these tips and steps to be successful every season. We get healthy plants that can withstand the transplant and the inevitable rough handling from mother nature.

  1. Start Your Seed at Strategic Times: When seedlings are started too early in the season, they tend to get leggy and suffer when they are finally brought outside. Read the instructions on your seed packet and do the math. Plant spring seedlings weeks before the last frost and fall seedling weeks before the first frost. Plant your seeds to late and you run the risk that temps will be too hot or cold for the plant, or the season will not be long enough for it to reach maturity.
  2. Use Water With Less Chemicals: If your water is treated, for example city water, the night before you start your seed, grab a pail or a large basin and fill it with water and let it sit overnight. This will allow some of the chlorine to evaporate. Room temperature water is best for watering newly sown seeds and young seedlings.
  3. Make Your Own Starting Medium: Start with compost. Sterilize a quart of compost spread on a tray lined with parchment paper. Bake it at 150 degrees Fahrenheit for 30 minutes. This kills pathogens and weed seeds that could hamper growth. Let the compost cool and in a tub or pan with tall sides, mix the sanitized compost with a quart of perlite, a quart of vermiculite and ¼ cup worm castings. Mix the ingredients well and then moisten well with the water you set aside. Mix again. There should be no dry particles. The tub should not be pooling with water. When working with vermiculite, it is important not to breathe in the dust. NOTE ABOUT VERMICULITE: Vermiculite is a mined mineral that expands when heated. It absorbs water and has become a popular soil amendment because it helps to retain moisture while allowing drainage, thus reducing the chances of plant disease There are reports that vermiculite could contain asbestos and this worry started when it was discovered that vermiculite used in house insulation contained asbestos. The mine that extracted the vermiculite with asbestos was closed in 1990. The Agency for Toxic Substances says, “Not all vermiculite garden products contain asbestos, but an EPA study showed that some contain low levels of asbestos. Asbestos was found primarily in the unmixed vermiculite product sold separately as a soil amendment. However, some was found in premixed potting soils. Because the Libby mine closed in 1990, newer products are not expected to contain significant amounts of asbestos. It is possible, however, that some older products could still be on store shelves.”  The bottom line? Use your judgement and do not stick your nose in the vermiculite. If you do not want to use this material leave it out of your seed starting process and substitute with finely screened coconut coir. To read more about vermiculite and the asbestos scare check out this .gov link. Cover seeds with plastic
  4. Prepare Simple Planting Containers: Choose small ones to start. We use small disposable, opaque, plastic drinking cups with one hole melted through the bottom for drainage. To make the hole, we warm up a soldering iron and quickly melt several holes simultaneously. We are not fans of DIY newspaper pots because they tend to steal moisture from the soil and rot or mold. Because we water from below by adding liquid to the tray under the cups, newspaper pots would not hold up well using that technique. Eggshell planting cups are trendy and fine for tomato seed but realize you will need to transplant the seedlings sooner than if you were using the small plastic drinking cups. Fill the cups with soil to ¼ inch below the rim and gently tap the cup on the counter to settle the soil. Do not add more soil.
  5. Plant the Seeds: Place a seed on top of the soil in each cup. Label the cups as you sow. Use small writing so you can reuse the cups again. Cover the seed with vermiculite to the proper depth given in the seed instructions. Moisten the vermiculite by misting gently with a spray bottle.
  6. Cover the Newly Planted Seed: I cut plastic sandwich bags in half to create pointy topped hoods for my cups. Secure a hood over each cup using a rubber band and place the cups on a waterproof tray with shallow sides. You will water your seedlings by adding water to the tray.
  7. Utilize a Heat Mat Made for Seed Starting: If your seeds need warmth to germinate, for example tomato and squash seeds, utilize a heat mat made for seed starting. Place the tray of seed cups on the heat mat and keep it there until the temperatures in the home reach the level the seedling needs to thrive. Heating pads to relieve a sore back should not be used around water. I read an article on Mother Earth News that recommended an electric heating pad (for personal use) but I’m not convinced that is a safe option. Heat mats for seed starting are not that costly. They lay perfectly flat and are waterproof.
  8. Bottom Water: You will not mist the soil. Your seed starting medium should be thoroughly moist to start. Add water to the tray, not to the top of the cups. Watering from above can disturb the seed. It also is difficult to mist a cup of soil adequately so that it is evenly moist. By watering from below, the seed starting medium will soak up the moisture like a sponge, ensuring even distribution throughout the entire cup. Water should not sit in the tray for more than 2 days. Try not to over water. Add more water before the seedling dries out.
  9. Use a Strong Light Source: Once the seed sprouts, remove the plastic cover and position the fluorescent light fixture or special grow light about 2” above the young seedling. Keep the light on for 16 hours every day.
  10. Wait to Fertilize until the First TRUE Leaves Appear: Once the second set of leaves appear (these are true leaves), fertilize the seedlings. Do not use miracle products made from synthetic chemicals. These produce fast growth which can weaken your plant, making it more susceptible to damage, pests and disease. Make your own organic fertilizer for your seedlings. Use purified water at room temperature plus kelp and fish emulsion. For a quart of water, add a teaspoon of each ingredient, mix and gently pour the water in the tray. Do not dump the fertilizer on the seedlings. Worm castings also make a wonderful first time fertilizer. Mix 2 tablespoons of work castings in a quart of water and water your seedlings from below.

Check out our post on how to buy tomato plants to transplant.

Learn how to properly save tomato seed.

When to fertilize seedlings