I will spray mine with the fish/seaweed mix from Neptune's Harvest. That is about all mine will get till I plant. Except for the ones I experiment with in the MG organic mix. Jay

When i replant them out of the trays into the little 6-8oz cups i use a mix of potting soil, coconut coir, perlite, and worm castings from my worms and then I mix in a little worm composite tea with tap water when I water them. Nothing excessive, just little shots for the little guys.

Yes, I feed my seedlings prior to transplant.

Whenever the seedling foliage indicates nutrient deficiencies, I apply soluable fertilizer diluted at about 25% of the recommended solution for post-transplant applications.

Example: Bad purple underleaf with leaf curl, thin tissued foliage, yellow withering cotyledons, pale spindly translucent stems ... time for 1/2 - 1 tsp. 15-30-15 per gallon water bottom-feed followed by 24 hours of florescent lighting (if real sunlight is unavailable), and some good air circulation. Interveinal chlorosis with crinkly looking leaves ... time to pot-up into a fresh mix dampened with the 15-30-15 solution plus a light micronutrient booster shot of Ironite and good air circulation.

No reason to stunt them early through neglect.

When you say "bad purple underleaf with leaf curl", does that include just purple leaf? Mine are not curled but has a case of deep purple underleaf. Anything I should do?

Diakon,

First of all, I should say that I don't apply fertilizer until the seedlings start looking like real live little tomato plants ... that is well after the second set of true leaves have spread out and the 3rd set is well emerged. But the original question was "do you feed your seedlings prior to planting out" and I assume this question is in response to many persons advising against or saying they don't fertilizing seedlings prior to planting them into the garden. This has been a long-standing argument at this forum.

Secondly, my tomato seedlings always have a bit of purple underleaf. And I attribute that to insufficient light and phosphorus (plants need both) for effective photosynthesis.

The florescent lights I use to produce seedlings indoors will keep plants growing, but it's just not the same as sunlight. And sterile starter media commonly used to start seedlings do not contain sufficient phosphorus needed for the conversion of light energy to chemical energy during photosynthesis. So, when I see a purple tinge to the underside of the seedling leaves, I don't get all worked up. It'll eventually go away when the seedlings are hardened off and set in the garden.

However, if the underside of the leaves want to roll over or curl under from the tips, I think the plant is cryin' out for nutrients and more light. This seems to occur as the second leaves become distinctly formed and the third leaves are partially or halfway emerged and the seedlings are four to six five inches tall.

If, in conjunction with the purple underleaf, the cotyledons (seed petals = sole source of initial nutrients for sprouts in a sterile medium) are beginning to yellow, I know for sure it's a nutrient thing since that's a sign of nitrogen deficiency (the plant is pulling nitrogen from the cotyledons up to the growing tip). Nitrogen deficiency at this stage can cause stunting ... and I think continuity of growth makes for better adult plants.

Also, I've noticed that when these obvious symptons of nutrient deficiency appear in tomato seedlings, a light dose of liquid fertilizer and an increase in the light level always spurs an overnight improvement in appearance and condition of the seedlings.

Now, interveinal chlorosis (lacey looking yellow and grey-green leaf tops) seems to accompany cramped, soggy plug cells when the seedlings are obviously too far along to remain in the intial seed cells. Seedlings will take on this appearance in plug cells when other seedlings of the same type and age transferred to 3 or 4-inch pots will look vigorous and healthy ... and when everything else is equal with regard to temperature, light, etc. While fertilizer will supply the micronutrients and nitrogen the seedlings are calling for, bottom watering applications just compound the saturated condition of the rootball. So, the best thing at that point, in my opinion, is to pot up and water in the new medium with a low dose of 15-30-15 plus a small amound of Ironite (or similar).

Now ... that's just what works for me. Others have different approaches and swear by different products. I'm sure there are home-brews and organic products that work as well for folks who prefer them as synthetic fertilizers work for me. I'm just answering the question the best way I know from experience. If I come across organic type nutrient suppliments that work as well, I'd gladly use them too.

I use fertilizer-enhanced potting soil to germinate all my tomato seeds, they sprout and grow just fine.

If you do fertilize your seedlings before transplant you need to use less than a half-amount of very slow release formula (like that in the enhanced potting soil) or dilute whatever liquid feed you use so that it's below 25% strength.

I like 10-10-10 or anything that has a lower first number (nitrogen) because with seedlings need roots and vigor more than top-growth which a high N formula will foster.

Thanks. Great tips