How to Find and Grow Kelp in Minecraft

Guide Java Bedrock

Quick answer: Find kelp in oceans (not warm, frozen or deep frozen ones), break it by hand, then plant it underwater on a block with a full top face. It has a 14% chance to grow on each random tick, and bone meal grows it by 1 block per use. Naturally it stops at age 25, so it reaches at most 26 blocks.

What you need

Kelp
Bone meal (optional)
Shears (optional)

Step by step

Find kelp in any ocean biome except warm, frozen and deep frozen oceans. It generates near and around seagrass.
Break it with any tool or your fist. It breaks instantly, and each block drops a kelp item. Breaking one block destroys all kelp blocks above it.
Plant it underwater. It goes only in water source blocks or downward-flowing water, never horizontally flowing water, on top of a block with a full top face. It cannot be placed on a magma block.
Let it grow. Each random tick has a 14% chance to grow it. At the default random tick speed of 3, a plant grows on average every 487.6 seconds. It needs no light.
Use bone meal to speed it up: each use grows it by 1 block.
Stop it growing by using shears on the top block, which sets its age to 25.
To farm it, break the top block each time it reaches age 25. The block below gets a random age from 0 to 24 and keeps growing, so the plant can go beyond 26 blocks.

Java vs Bedrock

The F3 age readout is Java Edition only. In Bedrock Edition, a killed wandering trader showing kelp as an offer has a 25% chance (+1% per Looting level) to drop 1 kelp if you hold an emerald.

Versions: Kelp stopped generating on magma blocks in Java Edition 1.17 (20w46a).

Frequently asked questions

How tall does kelp grow?

A planted kelp starts at a random age from 0 to 24 and stops at age 25, so naturally up to 26 blocks tall.

Does kelp need light?

No. It grows without any light level and without sky access.

Where can I plant kelp?

Only in water source blocks or downward-flowing water, on a block with a full top face. Not on magma blocks.

What can I make with kelp?

Smelt it with any fuel for dried kelp, which can be crafted into dried kelp blocks. It also has a 30% chance to raise a composter level.