Stardew Valley Speed-Gro Guide (2026): When Is Fertilizer Worth the Cost?

Revised November 11, 2026

Speed-Gro fertilizer is often used on every crop or ignored entirely. The correct question is whether the days you save are worth more than the fertilizer costs. This guide gives you the formula and the scenarios where each tier pays back.

Calculate Crop Profits Speed-Gro vs Deluxe

Fertilizer Comparison

Fertilizer	Speed	Cost	Source
Speed-Gro	10%	100g at Pierre	Farming 3 recipe / Pierre from Spring 15 Year 1
Deluxe Speed-Gro	25%	150g Pierre / 80g Oasis	Farming 8 recipe / Pierre Year 2+ / Oasis Thursdays
Hyper Speed-Gro	33%	Recipe costs 30 Qi Gems	Craft from Radioactive Ore, Bone Fragments and Solar Essence

Crafting costs depend on the value of your materials. Deluxe Speed-Gro uses 1 Oak Resin and 5 Bone Fragments to make 5 fertilizer. Its 40g sell price is separate from its acquisition cost. Hyper Speed-Gro uses 1 Radioactive Ore, 3 Bone Fragments and 1 Solar Essence per craft.

The ROI Formula

Build two harvest calendars for the same planting date and deadline. The game removes whole days from growth stages, so a percentage multiplication alone cannot give the exact saved days.

Added margin = extra harvest revenue − extra seed costs − fertilizer cost

A positive added margin improves this scenario.

Example: Starfruit + Deluxe Speed-Gro

Assume normal-quality raw sales, no profession, Summer Day 1 planting, immediate replanting, 400g seeds and 750g fruit.
Unboosted harvests on Days 14 and 27 give 2 × (750 − 400) = 700g per tile.
Deluxe Speed-Gro harvests on Days 10, 19 and 28 give 3 × (750 − 400) = 1,050g before fertilizer.
Buying one 150g fertilizer gives 900g margin, an improvement of 200g. At the Oasis Thursday price of 80g, margin is 970g, an improvement of 270g.

Check the full cost and deadline

This example excludes crop quality, machine processing, material costs and the time value of cash. Maintain watering and keep replacement seeds available.
For a bundle or quest crop, an earlier delivery can be valuable even when extra sale revenue is small. State that objective separately.

Best Scenarios for Speed-Gro

Season-end replanting

Check the specific crop's boosted harvest date before buying seeds. A generic late-season planting date does not fit every crop.

Starfruit third harvest

Summer Day 1 Starfruit with Deluxe Speed-Gro can fit harvests on Days 10, 19 and 28 when replanted immediately.

Ancient Fruit first harvest

An earlier first harvest shifts the weekly harvest schedule. Count the extra harvests inside your actual planning horizon.

Bundle and quest deadlines

An earlier crop may unlock a reward in time. Include that goal when sale-price profit is not your only objective.

When to Skip Fertilizer

Established regrow crops retain their regrowth interval after the first harvest.
Same harvest count may leave too little extra sale value to cover a purchased fertilizer.
Delayed application can lose reductions for growth stages the crop has already passed.
Limited seed cash means comparing fertilizer spending with the crop tiles you could plant using that gold.

Stacking with Agriculturist Profession

Agriculturist (Farming Lv10) adds +10% growth speed and stacks with fertilizer:

Deluxe Speed-Gro alone gives 25% growth acceleration.
Agriculturist adds 10 percentage points.
The combined bonus is 35%. Crop growth-stage rounding determines the harvest dates.

Compare the value of Agriculturist's actual extra harvests with Artisan's 40% sale-price bonus on eligible goods. Your crop calendar and processing throughput determine the outcome.

Artisan vs Agriculturist: Full ROI Comparison

Calculate If Speed-Gro Is Worth It

Set your season, days left, fertilizer and its per-tile cost to compare modeled crop margins.

Open Profit Calculator Greenhouse Guide

Frequently Asked Questions

Is Speed-Gro worth buying in Stardew Valley?

Compare the harvest calendar with and without fertilizer, then subtract fertilizer and additional seed costs from the value of extra harvests. Fertilizer can pay back when it fits an additional harvest inside your planning window. Crop price alone cannot establish the return.

Which crops benefit most from Speed-Gro?

Look for a crop whose earlier first harvest adds a harvest before the season or your deadline ends. Summer Day 1 Starfruit gives a clear example, with two unboosted harvests or three using Deluxe Speed-Gro when replanted immediately.

Does Speed-Gro stack with the Agriculturist profession?

Yes. The bonuses add. Speed-Gro plus Agriculturist gives 20%, Deluxe gives 35%, and Hyper gives 43% total growth acceleration. Actual harvest dates follow the game's crop growth-stage rounding.

When should I use Deluxe Speed-Gro?

Use it when an earlier harvest changes your result enough to cover its acquisition cost. Starfruit planted on Summer Day 1 can be harvested on Days 10, 19 and 28 with Deluxe Speed-Gro, compared with Days 14 and 27 without a growth boost.

Does Speed-Gro help with Ancient Fruit?

It advances Ancient Fruit's first harvest from its unboosted 28-day growth period. The seven-day regrowth interval stays the same, so count the actual extra harvests available by your chosen deadline.

Does fertilizer affect regrow crops after the first harvest?

No. Speed-Gro only affects the initial growth period. Once a regrow crop has produced its first harvest, the regrow timer is fixed and fertilizer has no effect.

Sources and calendar checks

The Wiki records fertilizer recipes, shops, additive profession bonuses and crop-specific growth tables. Check your platform version and mods before applying the dates.