Project List: Seed Starting
Growing your own ornamentals or vegetables from seed can be immensely rewarding. This
handout will mostly pertain to growing vegetables by seed. First, when to plant and whichseed? And, indoors or outdoors? These factors will depend on the time of year, as you’ll be choosing your seeds for either the warm or cool season. Refer to our Vegetable Planting Dates for North Texas handout for help with edible gardening. If you’re starting indoor seeds, you’ll also need the right supplies. Consult a Garden Advisor for help.
Seed Starting Guide
1. Choose your container
Whether peat pots, popup pellets, plastic pots or homemade options, make sure your
containers are clean and have drainage. If you are reusing containers, be sure to disinfect
them before planting to avoid the transmission of diseases.
2. Choose your soil
You can use a pre-packaged seed starter or coconut coir mixed with a 50/50 ratio of
vermiculite or perlite. After your mixture is ready, thoroughly moisten it. A sprinkling of
worm castings is a great addition to inhibit fungal diseases and contribute to overall seedling
Refer to the seed packet for proper planting depths, and plant with 1- 3 seeds to a cell, pot,
or pellet. Seeds planted too shallowly will dry out too soon, and those too deeply will not
4. Store unused seeds
Always keep your seeds in a cool and dry environment. Glass containers, plastic or paper bags
can work well, as long as the seeds are perfectly dry. Try using a refrigerator for longer term
storage, up to a year or two.
5. Control temperature
Warm-season veggies such as tomatoes require warmth in order to germinate. Use specially
designed seed heat mats to regulate temperatures for these crops. Cool-season crops such as
lettuces do not need such warmth, therefore for them, supplemental heat is not required.
6. Provide light
Good light is required for vigorous growth. 12-16 hours is best. Make sure your light is adjustable
to allow for growth: 2-3 inches above your seedlings is optimal to begin with. This produces
stronger, stouter plants that will survive transplantation better.
Initially, your seedlings must not dry out. Your growing medium should stay moist like a damp
sponge, but not dripping wet. To water, rather than doing it from above, mist with a fine
spray. Or, you can water the entire seed tray by immersing it in a larger pan, and allow the
pellets or pots to wick up the moisture from beneath.
Thin out your seedlings after approximately 4-6 weeks. The strongest get to survive. Pick away
or carefully use scissors to remove smaller, less vigorous sprouts leaving only one sprout per
cell or pot.
Go easy- ‘feed’ using a solution of only liquid seaweed or fish emulsion diluted to 1/4 the recommended rate once the first set of ‘true’ leaves– the second set—emerges. Any heavier
feeding is not good for young seedlings.
10. Harden off
Tough love, but the young plants must slowly get used to their new surroundings. ‘Harden off’
seedlings a week prior to planting in ground. Set them outside in a shaded, sheltered spot
during the day. Bring them in before dark, or before periods of rain or heavy winds.
Plant your new transplants into the garden, or into your choice of a larger container.
There can be several factors that can cause your seeds not to germinate. Poor quality or old
seeds (2-3 years), planting too deeply or not deeply enough, or under- and over-watering. If
your seedlings are ‘leggy’ or spindly, adjust the height of your grow light, as they are reaching
for a light source. Consider using a fan for air, and proper watering and drainage techniques
to minimize the chances of disease.
Garden Help in North Texas
Seed starting can be quite complicated, especially growing in indoor situations. Speak to one
of our Garden Advisors for help in growing your own from seed!