Seed Starting Basics

Seed Starting Basics the Natureworks Way Grow Organic!

Click here for a printable version of this handout

What to start indoors:

  • Tomatoes, peppers, eggplants must be started indoors, 6-8 weeks before last frost
  • Many other vegetables can be started 6-8 weeks before setting out Refer to our handout Vegetable Crop Timing for specific crops

Choosing seed:

  • Read the packet, check for taste, vigor, production, disease resistance, season length
  • Buy untreated seed that is not genetically engineered. Seek out organic seed. Natureworks proudly offers a diverse and hand-picked selection of the best seed from many seed suppliers

Use an organic, high quality seed starting mix

  • We recommend Organic Mechanics Seed Starting Blend Potting Soil
  • A sterile mix is imperative to prevent diseases
  • This mix holds moisture, yet drains well for healthy root growth
  • Contains: coconut coir, pine bark, rice hulls, and worm castings


  • Some seeds need light, others should be covered. Refer to each seed packet
  • Heat mats (sold at Natureworks) are very useful, especially for warm season crops such as tomatoes and peppers
  • Cover seed trays with a plastic dome (sold at Natureworks) or plastic wrap as the seeds are germinating


  • Light is needed after germination. A southern window in the winter does not offer enough sunlight to grow healthy seedlings. It is very helpful to supplement with artificial lights
  • Use florescent or LED shop lights or 300 watt grow lights (sold at Natureworks)
  • Keep shop lights 1-3” from seedling tips. Adjust as the seedlings grow Dust light tubes often
  • Keep lights on 14-16 hours per day
  • Air temp should be around 60 degrees
  • Keep a fan on low circulating air around your seedlings to prevent disease in the soil and strengthen your seedlings


  • Use room temperature water
  • City water is chlorinated; chlorine evaporates after 24 hours in an open watering can
  • It is best to water from the bottom
  • Mist if humidity is low or place a humidifier in the room where you are growing seedlings


  • Once seeds have germinated and have grown a couple of sets of leaves, start fertilizing
  • Feed your seedlings at half the strength recommended on the fertilizer label. We use Neptune’s Harvest Fish Emulsion and Liquid Seaweed or Sustane Flourish.
  • Feed your seedlings weekly


  • When your seedlings outgrow their cells or small starter pots, transplant into 4-inch pots, using Organic Mechanics Seed Starting Blend Potting Soil
  • Liquid seaweed or compost tea makes a wonderful root drench when first transplanting seedlings. We sell liquid seaweed (dried kelp) and Sustane Compost Tea Bags. Both are very helpful in getting the hard working, tiny feeder roots to grow, thus helping your new plants establish with less stress

Hardening off:

  • Seedlings are not accustomed to direct sun even if they have been grown in a sunny window indoors
  • Seedlings are unable to tolerate strong winds when first brought outside
  • Hardening off is the term used for gradually getting your seedlings used to sun and wind and outdoor conditions. You must acclimate your seedlings as they move from indoors to outdoors. Protect from direct sun and wind in a sheltered spot outdoors
  • Begin the hardening off process a minimum 10 days before planting out
  • At first, set your seedlings outside in dappled shade for 1 hour on a day with no wind or rain
  • Gradually increase the time outside and gradually move them into stronger light

Soil Temperature

  • Every vegetable seedling has an ideal soil temperature that is needs to thrive when first set out in the garden. We always use a soil thermometer (sold at Natureworks) and the accompanying chart to determine when it is safe to plant seedlings as well as direct sow seeds in the ground


  • Expect a frost in the spring in our area of CT up until May 15-30th . Frost will kill or damage warm season plants. Refer to our handout Vegetable Crop Timing for specific crop needs
  • Always keep your eye on the weather when you are hardening off and planting seedlings in the ground. If a frost is threatened, cover your plants with metal hoops and floating row covers (sold at Natureworks). You may also use cotton sheets or fabric. Do not let plastic touch your plants as it will transmit the cold

In an effort to provide horticultural information, these educational documents are the property of Natureworks Horticultural Services, LLC. You are granted permission to print/photocopy this educational information free of charge as long as you clearly show that these are Natureworks documents.