Alchemy Factory Fertilizer Guide: Tiers & Ratios

The ladder

Fertiliser recipes were rebuilt just before Early Access: “Clay and Sand no longer serve as fertilizer. Added specific Fertilizer and related recipes.” Since then the tiers guides describe are:

1. Basic fertiliser in the opening tiers.
2. Advanced fertiliser at tier 5. Table saws split rotten logs into gloom fungus and planks; the planks are a byproduct you must dispose of or the fungus stops flowing. One guide sends them into Jupiter relics, another into the trash; both warn against tying them to coke powder production because then fertiliser depends on fuel being burned.
3. Growth potion, the first “dense” fertiliser. Once it unlocks, “no product in the game needs advanced fertilizer,” so the tier 5 build is a stepping stone.
4. Fertile catalyst, which is also an Advanced Athanor catalyst (doubles product output) and an ingredient for obsidian and panacea potions.
5. Panacea potion, the end of both ladders: fuel and fertiliser in one belt. Late-game floors run a single panacea line for furnaces and nurseries together.

The skill that matters

Fertilization Efficiency raises fertiliser efficacy by 10% per point. The March 2026 skill guide puts the first points into it at tier 5, when advanced fertiliser arrives and flax, sage and red currant demand jumps, and later raises it to 10 to 15 points for growth potion, fertile catalyst and panacea builds. The reasoning is that cauldron-heavy factories are nursery-heavy factories, and fertiliser is the input they all share.

Why nurseries break cauldrons

Nurseries are not affected by the Factory Efficiency skill. Machines and cauldrons speed up with it; plants do not. The cauldron guide’s worked case: two points of Factory Efficiency raise a clay cauldron from 16.7 to 25 per minute and its heat from 4.6 to 6.9 P/s, but the nursery stack behind it still makes 60 per minute, so a three-cauldron stack that needed 50.1 now needs 75 and starves. The fix is to raise Logistics Efficiency alongside, or leave both where they were when the ratios were balanced.

Numbers from the comparison builds

From the February 2026 extractor comparison, at default rates with no upgrades:

• Two red currant plants feeding twelve standard extractors used 24 advanced fertiliser per minute; the thermal route with one plant used 8.
• Scaling to 5,400 fruit wine a minute needed 36 advanced fertiliser per minute on thermal extractors and about 108 on standard ones, “so your constraint is really on fuel, not on fertilizer” in the thermal case and the reverse in the standard case.

The guide’s conclusion applies to the whole fertiliser question: once resources are effectively infinite, choose by footprint and by which belt you would rather run, not by raw cost.

Practical rules

• Every floor carries a fertiliser line (with money and fuel), or the nurseries on it stop.
• Device buffers only hold twice the slot count of fertiliser since March 2026, so a stalled belt shows up fast.
• Gelatinous Gridlocks can lock two of a nursery’s three fertiliser slots so a small stack primes it.
• Lavender oil, linseed oil and the other liquid inputs to catalyst recipes come from alembics and extractors; the thermal extractor guide covers the height bonus.

Sources: Demo-to-EA notes (11 December 2025); Uglarvisk, “Mastering the Alchemy Factory Skill Tree” (17 March 2026), “Mastering the Cauldron Guide” (12 March 2026), “The BEST Coke Powder Recipe” (8 April 2026) and “Comparing Thermal Extractors with Standard Extractors” (24 February 2026), all transcripts; v0.4.3.4131 buffer change (6 March 2026).