Tomato Fertilizer Schedule
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GardenSays
The tomato feeding schedule: feed before planting, hold, then sidedress when the first fruits reach about 1 inch (golf-ball size), repeating every 21-28 days.
- Fertilizer
- 10-10-10
- Amount
- ≈ 0.5 lb
- Next feeding
- At first fruit
The whole season has just three feeding moments: (1) now, before planting; (2) nothing while the plant grows and flowers; (3) sidedress when the first fruits reach about 1 inch (golf-ball size), repeating every 21-28 days while fruit keeps coming. Everything else is noise.
- 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.
Do this this week
- 1.Spread ≈ 0.5 lb of balanced fertilizer (e.g. 10-10-10) evenly over the 32 sq ft bed
- 2.Work it into the top 6 inches a few days before planting
- 3.Then hold — nothing more until when the first fruits reach about 1 inch (golf-ball size)
Typical estimate · 2 verified sources · Checked 2026-07-15 · How we decide
Why
For a 32 sq ft bed, that's roughly 0.5 lb (8 oz) of fertilizer, spread evenly and worked into the top 6 inches a few days before planting. 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.
- 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)GardenSays 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
- 3. Your bed≈ 0.5 lb (8 oz)Calculated result
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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People also ask
How often do you fertilize tomatoes?
The tomato feeding schedule: feed before planting, hold, then sidedress when the first fruits reach about 1 inch (golf-ball size), repeating every 21-28 days. Calculate yours →
When to fertilize tomatoes after planting?
Usually nothing now — wait until when the first fruits reach about 1 inch (golf-ball size) (one catch-up feeding is fine if you never fed at planting). Calculate yours →
Can you over-fertilize tomatoes?
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