Seed Needs Checklist

by Isabel Vinton

For a gardener, who sows hope for the season and love for the earth with their seeds, nothing is more disheartening then waiting in vain to see sprouts poking through the soil, or watching your beloved seedlings fail to thrive. Just like you and me, seeds have some basic necessities, and by tending to those needs, you can give your garden the best chance to flourish.


Direct sowing on the farm.

At this point in the season, gardeners are growing seedlings in both of the two principal ways: indoor growing and direct seeding. Indoor growing--whether you have a fully equipped greenhouse or a single heat lamp on your kitchen counter--is necessary for many seeds that need a long growing season but can’t tolerate the harsh conditions of early spring. Direct sowing is great for those more cold-hardy crops, as well as those that don’t react well to transplanting. While many basics apply to both, it's important to know what makes each method of growing distinct. Follow this checklist for healthy seedlings.

Air: One of the most important and most often forgotten points. Sometimes you may feel like you just need some room to breathe--and so do your seeds! A lack of air circulation can encourage diseases to spread and lead to damping off, a fungus responsible for taking down seedlings shortly after they’ve sprouted.

  • Growing indoors? Damping off is probably the single most common ailment seen in seedlings grown indoors. It is a fungal affliction in which the young seedling's stem withers at soil level; the seedling topples over and usually dies. Don’t keep seedlings cooped up in small rooms, and if using cold frames or greenhouses, make sure they have ventilation or even fans.
  • Direct seeding? Make sure your plot has access to a natural flow of air.

Water: We all know how important water is for life, but the amount of water is just as important. Every kind of seed has its own unique water requirements. No seedling, however, likes to be overwatered. In addition to air circulation, overwatering is the main cause of damping off, as well as rot and other diseases. While it’s good to keep soil moist for freshly-sown seeds, you can ease off on the watering can as soon as they germinate, and if you do happen to overwater, let the soil dry out a bit before watering again. When watering, be sure the flow is light so as to keep seeds in place and seedlings undamaged. It can even be a good idea to moisten the soil before sowing and then water gently as needed.

  • Growing indoors? Some seed starting trays allow you to water from the bottom, ensuring the surface, stems, and leaves stay dry while the roots stay moist. You can also cover them (loosely!) to maintain moisture, and then remove the covering as soon as they germinate.
  • Direct seeding? It can be tempting to leave your garden’s fate up to the elements, but be careful! Don’t wait all week for that 60% chance of rain, and check the soil frequently on hot days.

Light: You’d be hard-pressed to find a child who didn’t learn all about photosynthesis in school. And while we may not remember all the steps of the cycle, we got the gist: plants need light! Despite how well-acquainted we are with this idea, you can still never emphasize enough how important it is; without light, your seedlings simply can’t thrive. If you see thin, stretched out, leggy seedlings, chances are they're not getting enough light.

  • Growing indoors? Make sure they have adequate exposure to light for 12-14 hours a day Unfortunately, even the sunniest of window sills can’t accommodate this need, so it may be time to invest in flurorescent bulbs. Keep the lamp 3-4 inches from the top of the seedlings as they grow, and rotate the trays so your plants don’t become distorted reaching towards the lamp or window.
  • Direct seeding? Alas, we can’t ask the sun to work overtime no matter how much we love our gardens. Check the seed pack for light preference. Some, like Ashworth Sweet Corn, require full sun. Our Shade Garden Mix, on the other hand, thrives in those back corners of your yard. Keep all this in mind when planning out your garden.

Heat: Just like most people would rather stay inside when its cold out, most seeds will stay dormant without enough warmth, and any sprouts that do emerge won’t be thrilled at their chilly surroundings. While the amount of heat needed differs for different plants (some, like Nozaki Chinese Cabbage and Mache thrive in colder conditions), it’s generally good to make sure your seedlings will have a warm welcome.

  • Growing indoors? These are more likely to be species originating from warmer climates--things like tomatoes and peppers--and keeping them indoors is all about keeping them out of the cold. Unless your thermostat is turned up to 80, purchasing a heating mat can be the best way to meet their needs.
  • Direct seeding? Luckily, lettuces, peas, root veggies, and many other crops will do just fine if planted in cold and even freezing conditions. However, it’s always good to check both the pack and the weather to make sure your seeds can tolerate the conditions they’ll be planted in.

Nutrients: Next time you’re hankering for a snack, remember that your seedlings get hungry, too! Neither the priciest of potting soil nor the most fertile of earth can give every seed what it needs. Be sure to supplement with compost and organic fertilizers--just be cautious not to clog up the drainage of the soil with rich additives.

  • Growing indoors? While some say sterile potting soil can prevent disease, it can also mean a lot of the good stuff is missing. Store-bought fertilizers and compost can help add some of it back. Yellowing leaves are usually a symptom of nitrogen deficiency, which is usually only a problem in a potting soil that is not fully amended with compost and organic amendments such as seedmeals. Be sure that if you are using a sterile soilless mix that it either comes with fertilizer included or you are providing some yourself--or, better yet, choose an organic, compost-based mix from the start.
  • Direct seeding? Use your gardening tools to loosen your soil to a depth of 8-12 inches. While the addition of any organic matter will do, it can be helpful to know what soil type you have in your backyard and how that affects the texture and makeup.

Do you have a specific seedling ailment? Check out these 5 common seedling issues and ways to prevent them.