Fertilizer

Accurate as of the Power Line Update (Q3 2026).

Description

Fertilizer makes plants grow faster and produce more. It can be made in the Portable Composter or Advanced Composter.

Composition

Each fertilizer is made from 3 ingredients, which can be any combination of biomass, decayed food or food (raw or cooked). When more than 3 ingredients have been added to a composter, the fertilizer will be based on the weighted average of the inputs. Each type of ingredient has its own effect on the end result:

Cycles = 2 + 5*Biomass Ratio
Yield Boost = 1 + 1.5*Food Ratio
Growth Speed Multiplier = 1x + 0.25x*Decayed Food Ratio 

Hay harvested from Switchgrass is counted as biomass instead of food.

Merging two stacks of different fertilizers will cause the resulting fertilizer's stats to be a non-weighted average of both fertilizer stack stats.

Application

1 Cycle of fertilizer is consumed from a tray when a new plant is planted or perennial plant is harvested, applying the fertilizer's effect to the plant for its growth cycle. If the number of cycles remaining in the fertilizer after this is less than 1, the fertilizer is destroyed and needs to be re-added before a new planting or perennial harvest in order to apply effects to future plants/perennial growth cycles.

Adding fertilizer to a tray with an existing plant doesn't apply fertilizer to it and doesn't consume a fertilizer cycle.

When fertilizer is applied to a plant, the yield boost stat is rounded, with 0.5 rounding to the nearest even number (banker's rounding), and the number of plants created during transition to the harvest stage is increased by the rounded amount. As an example, with a rounded yield boost of 2, Switchgrass's yield changes from 15 to 17 hay, but Watermelon yield changes from 1 to 3 watermelons. The original plant yield boost stat is retained if the fertilizer is removed from a tray(by disassembling it).

Optimization

Because of the yield boost rounding mechanics, there are only two optimal ratios for food in a composter: 0% (increasing yield by 1) and 1/3(increasing yield by 2).

Because of the cycles mechanic, there are 6 optimal ratios for biomass: 0% (2 cycles), 20%(3 cycles), 40% (4 cycles), 60%(5 cycles), 80% (6 cycles) and 100%(7 cycles).

The remaining ratio after yield/cycles ratio choices should be filled with decayed food.

Wheat is the best plant for fertilizer food production. Switchgrass is the best plant for biomass and decayed food production due to its higher yield/time.

Producing decayed food

The following conditions gave the shortest decay times.

• Gas: Pollutant
• Pressure: <0.2 kPa
• Temperature: >200 °C
• Cooked food decays slightly faster than raw

A Fridge Small can be used instead of building a room with this type of atmosphere. Gas at very low pressures can't be heated by a Pipe Heater, the gas should be heated before reducing its pressure.

An alternative is passing decayable food through a SDB Silo, which turns it into decayed food on exit.

Base growth times for plants

Plant	Planting -> Mature (s)	Mature -> Seeding (s)	Harvest -> Mature (s)
Switchgrass	4130	666	1332
Strawberry	15000	3000	3000
Tomato	11700	2700	2700
Blueberry	15600	3000	3000
Watermelon	15600	3000	3000
Potato	3000	1000	N/A
Corn	5400	1800	N/A
Darga Fern	3600	1200	N/A
Fern	2400	800	N/A
Cocoa	15000	2100	6300
Sugarcane	3330	666	N/A
Wheat	2700	900	N/A
Soybean	3600	1200	N/A
Rice	3600	1200	N/A
Pumpkin	14400	2400	7200
Mushroom	3600	4800	N/A
Winterspawn Alpha	2160	720	N/A
Winterspawn Beta	3600	1200	N/A
Hades Flower (Both)	2160	720	N/A