Tomato Fertilizer Schedule

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GardenSays

Work about 0.5 lb of balanced garden fertilizer (e.g., 10-10-10) into your 32 sq ft bed before planting.

Fertilizer: 10-10-10
Amount: ≈ 0.5 lb
Next feeding: At first fruit

For a 32 sq ft bed, that's roughly 0.5 lb (8 oz) of balanced fertilizer, spread evenly and worked into the top 6 inches a few days before transplanting. A soil test beats any rule of thumb — if you have one, follow it instead.

Then hold off: no more fertilizer until when the first fruits reach about 1 inch (golf-ball size). Feeding again too early is the classic way to get a huge green plant with no fruit.

⚠ Blossom end rot is a calcium/uneven-watering problem — more fertilizer won't fix it and extra nitrogen makes it worse.
⚠ Skip high-nitrogen lawn fertilizers: they push leaves at the expense of fruit.

Why

✓One balanced pre-plant application plus a fruit-set sidedress matches how demand actually rises.
✓Moderate nitrogen, ample phosphorus — excess N before fruit set gives lush vines and few tomatoes.

When this doesn't apply

→Soil test results override this: high-P soils need nitrogen-only products.
→Beds heavily amended with compost each year may need only half this rate.

How this was calculated

1. Feeding profile
Tomato: Moderate nitrogen, ample phosphorus — excess N before fruit set gives lush vines and few tomatoes.
2. Pre-plant rate1.5 lb/100 sq ft (our estimate)
balanced garden fertilizer (e.g., 10-10-10): 1.5 lb per 100 sq ft (midpoint of published extension rates), worked into the top 6 inches
Our estimate, derived from the cited guidance.
3. Your bed≈ 0.5 lb (8 oz)
1.5 lb/100 sq ft × 32 sq ft

Data sources

University of Minnesota Extension — Growing tomatoes in home gardens — Use a starter fertilizer at transplant; sidedress nitrogen when fruits are about 1 inch in diameter and again 3-4 weeks later; avoid excess nitrogen. (checked 2026-07-15)
Ohio State University Extension — Growing Tomatoes in the Home Garden — Apply a balanced garden fertilizer before planting (published rates typically 1-3 lb per 100 sq ft); sidedress after first fruit set. (checked 2026-07-15)

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