Starting Seeds Indoors

Why start seeds indoors? Starting seeds indoors is a less expensive way to jump-start the gardening season rather than buying plants from the garden shop.

Why not just plant the seeds in the ground? Starting seeds indoors extends the growing season for plants.

Why is this necessary? Because many of our food and ornamental flowering plants are actually tropical plants. Examples are tomatoes, peppers, eggplant and impatiens. Planting them from seeds in the northern growing zones does not give them time to produce much flower and fruit. 

The Basics of Starting Seeds Indoors--Containers

Almost anything can be utilized as containers for starting seeds indoors:

  • plastic trays from the garden store
  • egg cartons
  • paper drinking cups
  • empty cans
  • peat pots from the garden store
  • newspaper cups you build yourself

Be sure they are clean. Wash hard containers in soapy water. Poke holes in the bottoms of the containers.

--Soil-less Seed Starting Mixture

Do Not Use Garden Soil or mixtures containing soil. You can buy  soil-less mixture from you local garden store or online. Or you can make your own.

  1. In a large, clean container mix 2 gallons of peat moss and 2 gallons of perlite, anthracite, or sand. 
  2. Mix together 4 tablespoons ground limestone and a small amount of general-purpose, time-release fertilizer. 
  3. Mix into the peat mixture. Add enough water to moisten.
  4. Fill the planting containers with the mix. Tamp down to eliminate air pockets.
  5. Plant seeds to depth listed on the seed packet: 
  • small seeds--2 or 3 per container
  • large seeds--1 per container--plant the largest seed in the packet

      6.  Set little pots in a plastic or metal tray--a glass casserole dish would work.

      7.  Cover with plastic wrap or a clear plastic sheet. Poke holes in the cover with a toothpick.

--Provide Warmth 

Seedlings need 65-75 degrees F for several hours each day. Optimal warmth would be a heated pad under the tray. 

--And Light

When seedlings appear, remove the plastic cover and move into a bright light. Window light is not ideal. It is too weak and too directional. An intense overhead white light is optimal. After germination, leave it on 12-14 hours a day. Turn it off at night because photosynthesis needs a dark period to work properly.


Use a mister bottle to water newly planted seeds. After germination, keep the plants watered well. Water gently so as not to disturb the roots. A turkey baster is ideal for this, or pour gently from a small container.

When seedlings get the second pair of leaves, repot into individual containers and water well.

Moving Seeds Outdoors

Harden Off seedlings for 2 weeks before planting outdoors.

Start moving little plants outdoors for increasing periods each day. Put in the shade at first during the afternoon warmth. Protect from the wind. Bring in at night. Do this for longer and longer periods each day.

After 2 weeks leave in a sunny spot for a day or two. Plant into the ground on a cloudy day or later in the afternoon on a sunny day. If you are planting in compostable containers such as peat posts or newspaper pots, make some slits in the sides with a knife so the roots can spread easily. Also trim the top edges off.

Plants could be hardened off in a cold frame.

Perlite is volcanic glass that is mined and heated in big ovens until it pops into round, white material. Anthracite is hydrated magnesium aluminim silicate which resembles mica in appearance. These materials are used in seed starting and potting mixtures to lighten the soil, allowing more air around the roots of plants and to help retain moisture. Sand can serve the same purpose.

Ali, of Reno Nevada. planting zone 7, has started her seeds indoors. She writes: Planted some seeds that I saved from last year's harvest, indoors in a very bright windows room. Here I go beginning of my 2017 garden...

Notice that she used egg cartons for some, with 2 wells that she actually used egg shells. When she plants, all she has to do in use a toothpick to put some holes int the shells, then plant the whole thing.  In the back are two other plantings. She put the containers into plastic tubs for easy watering and moving. 

Check out Ali's 2016 garden.

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