Seedling Production – Under Lights

Q.  I am very discouraged.  I tried to start some tomato plants on my
kitchen counter under a flourescent light and after getting big enough to have their second leaves, they all wilted and died.  Does anyone have a clue what I should have done?  I have a sunny window, do you think that would help?  I’m really not sure what I did wrong.  They didn’t get dry, as I could always feel some moisture in the seed starting potting soil.

A.  Starting seedlings in a protected environment is a great way to extend the growing season – if we do everything right.  Let’s review the steps to assure the highest chance for success, since it could mean you have tomatoes, peppers, etc. 6-8 weeks earlier!

1)  The planting medium must be “sterile”, meaning never used for growing things before.  A mixture using sawdust, peatmoss, perlite, vermiculite, and sand – in any combination you like, but with sand at 25% to 35% by volume.  All ingredients are not necessary – even straight sawdust can be used with sand, if necessary..

2)  For each flat 11″ X 20″ in size, add 3 level tablespoons of Pre-Plant and thoroughly mix with the planting medium.  For the Pre-Plant formula, look under Fertilizers in the Gardening Techniques section of the website, or in all of Dr. Mittleider’s books.

3)  Plant seeds – evenly spaced in shallow furrows in the flat or tray – no more than 600-800 per tray.  Cover with 1/8-1/4″ planting medium.

4)  Cover with light-weight burlap or cheesecloth and water with plain
water.

5)  Place in a dark location with temperatures of 70+ fahrenheit (soil
temperatures – not necessarily air temperatures).  A heating pad can be
helpful to achieve this in a cool basement or garage.

6)  Water with plain water (never use fertilizer on un-sprouted seed!) often enough to keep the soil moist, but not soaking wet.

7)  At the first signs of plants emerging from the soil, water with Constant Feed Solution, consisting of 1 ounce Weekly Feed dissolved in 3 gallons of water, then remove the covering, and place under maximum light.

8)  A twin-tube shop light, with one cool and one warm tube will give a
decent spectrum of light.  Keep the lights very close to the plants, to
maximize the light.  Never use a light that is hot.  Heat can very easily burn the tender new plants.  Light should be applied for at least 12-16 hours per day.

9)  Water with Constant Feed Solution daily or as needed to maintain soil moisture – but do not over-water.  Too much water can drown the plants, and can also lead to Damping-Off disease, which destroys the stem at the soil surface and kills the plant.  Use Constant Feed Solution until plants are placed in the garden.

10)  Change the plants’ positions occasionally, to assure even distribution of light to all plants.

11)  Maintain temperatures in the 60-75 range.  The warmer it is, the faster your plants will grow, so to slow them down, lower the temperatures.

12)  By the time plants have their second set of true leaves, transplanting into pots, 6-paks, or other flats should be done.  Always mark flats, to space plants evenly.  This assures even distribution of light, air, food, and water to all plants.

13)  Always water both plants and new destination planting medium before
transplanting.

14)  Use a “dibble” to loosen soil around plant roots, carefully remove
plant from the soil, holding by the leaf only, and place in a hole large and deep enough to accommodate the root ball and soil without crowding.  Plant down to the crown or growing tip, but never get soil on the growing tip, which will kill the plant.

15)  Using dibble, assure that soil is in contact with plant roots, but do not pack soil tightly around plant stem and roots, as this will damage the plant.  Water immediately, which will settle the soil around the roots.

16)  Maintain maximum light, and immediately prune overlapping leaves or
transplant into larger pots, to avoid plant stems “stretching” to seek
light.  This will produce week, spindly plants that will never be as strong and robust as those which are short and stocky.

17)  Before transplanting in the garden, place plants outside for 2-3 days to “harden-off”, or become accustomed to the outside climate.  Bring them inside at night if frost is threatened, and do not transplant in the garden until it is safe to do so, unless plants are protected with “mini-greenhouses” or other coverings.

As this is reviewed and critiqued, it may well be edited and revised.  Your feedback is welcomed, as always.