Planting Tomato Seedlings
In the previous post, I covered soil prep. Now it's time to plant.
Tomatoes: A Quick Fun Fact
Tomatoes are the most beloved vegetable (well, technically a fruit) in American gardens. If the seeds are inside the produce, it's botanically a fruit — and in 1893, the Supreme Court agreed... for tariff purposes, anyway, which officially classified it as a vegetable.
Eggplant, peppers, zucchini, summer and winter squash, butternut, and pumpkins are all technically fruit too.
How I Prep the Planting Hole
I start with a bed already filled with topsoil and composted manure, then add another layer before planting. For each hole:
Composted manure
Worm castings
Homemade compost
A few books of paper matches (a boost of sulfur)
A balanced NPK fertilizer with an extra touch of potassium
Water the hole well after adding amendments and watch how fast it drains. If it just sits, mix in more organic matter like peat moss — especially important if you have clay soil.
A note on fertilizer: Do not over-fertilize, especially with nitrogen. Too much nitrogen = lots of green leaves, few tomatoes.
Quick NPK Reference:
N (Nitrogen) — green leaves and stem development
P (Phosphorus) — root development
K (Potassium) — fruit development
Mostly green crop like lettuce? Add a pinch of N. Want strong roots? A little extra P. Want great tomatoes? Lean into K.
If you don't want to mix your own, a good organic 10-10-10 fertilizer works — buy one small bag of each so you can adjust as needed.
Before You Plant: Soak the Seedlings
Whether your seedling is in a 6" pot or a 6-pack, soak it in a bucket or tray of water until every inch of potting soil is saturated.
Two Ways to Plant Tomatoes
Remove the bottom branches before planting — tomatoes grow roots along the entire stem, so the more stem you bury, the stronger the plant.
Vertical planting: Place the seedling at the same depth as it was in the pot, or slightly deeper.
Horizontal planting: Remove the bottom leaves and lay the entire root system and stem in a shallow trench, giving the top a slight upward angle to encourage vertical growth.
I use tomato cages from Gardener's Supply (gardeners.com) — great cages, just keep an eye on them staying attached.
Determinate vs. Indeterminate: Know the Difference
Determinate tomatoes:
Ripen faster than large varieties
Almost all ripen at the same time — ideal for canning
Perfect for getting the first tomato of the season
The timing secret: Aim for seedlings that are 10 weeks old at transplant. Start in seed trays, then at 6 weeks move to milk cartons for another 4 weeks. Use The Harvest Helper Planting Wheel to find your frost date — plant 3 weeks before it (with frost protection) and you'll be harvesting up to 7 weeks ahead of gardeners who wait until after the last frost.
Indeterminate tomatoes:
Keep growing as long as they're in the ground or until frost kills them
Usually 70+ days to harvest
Grown the same way, you can enjoy one-pounders for almost 2 months longer than usual
I always grow both — determinates for the early win, indeterminates for the long season.
There's a lot more to tomatoes than one post can cover. Page 261 of The Harvest Helper goes deep — from starting seedlings to saving seeds. Grab your copy →