Crop farming basics, then an auto farm in Minecraft

Till Dirt within 4 blocks of water, plant two crops in alternating rows and they grow twice as fast as a field of one crop. Once you have enough seeds, a farmer villager can harvest and replant the whole field for you. All numbers come from the Java Edition 26.3 code; Bedrock Edition grows crops with different odds.

• Break Short Grass: each one has a 12.5% chance to drop Wheat Seeds.
• Villages grow Wheat, Carrots, Potatoes and Beetroots. Take only the fully grown crops and replant the rest.
• Zombies killed by a player rarely drop a Carrot or a Potato.

Carrots and Potatoes are their own seeds: you plant the item itself.

Use a hoe on Dirt, a Grass Block or a Dirt Path to turn it into Farmland. Farmland stays wet when water is within 4 blocks horizontally, on the same level or one block higher. Rain also wets it.

1. Mark a 9 by 9 square and dig out the center block.
2. Pour a Water Bucket into it. That single water source hydrates all 80 blocks around it.
3. Till the 80 blocks. Wet farmland turns darker within a minute or two.

Dry farmland with nothing planted on it turns back into Dirt after a while, so plant right away.

Every random tick, a crop grows one stage with a chance that depends on the farmland under and around it. A crop that has the same crop on both sides and diagonally gets that chance halved. Rows of two different crops avoid the penalty:

Plant a row of Wheat, then a row of Carrots, then Wheat again, and so on. Wheat, Carrots and Potatoes have 8 stages; Beetroots have 4 but skip one random tick in three. Crops only grow while you are close enough for the chunk to be loaded.

• Crops grow at light level 9 or more; below 8 you cannot even plant them. Under the open sky, daylight counts even at night. Indoors or underground, place a Torch within 5 blocks of every crop.
• Do not jump on farmland: a normal jump turns it back into Dirt about 3 times in 4. Walking on it is safe.
• Fence the field. Animals and mobs trample it too, unless they are as small as a chicken.

Break a crop at its last stage. Before that, it only gives back 1 seed or 1 item.

A tool with Fortune adds one more try per level: with Fortune III, Carrots and Potatoes give up to 7. Replant each block right after you harvest it.

Bone Meal on a crop adds 2 to 5 stages at once, so 2 or 3 uses grow Wheat, Carrots or Potatoes from scratch. On Beetroots it adds one stage 3 times in 4.

Turn your spare seeds into Bone Meal with a Composter (7 Wooden Slabs). The first item in an empty composter always adds a layer; after that, seeds add one with a 30% chance, crops 65%, Bread and Hay Bales 85%. After 7 layers, the composter gives 1 Bone Meal. That is about 21 seeds or 10 Carrots per Bone Meal.

A farmer villager harvests fully grown crops within reach and replants them with the seeds it carries. It also composts its spare seeds and bakes Bread from Wheat.

1. Put a Fence around the 9 by 9 field, on the ring of blocks just outside it: 40 fences.
2. Replace one corner farmland block with a Composter.
3. Plant the field with Carrots and Potatoes in alternating rows: they are both seed and food for villagers.
4. Bring an unemployed villager inside (see how to breed villagers). It takes the Composter and becomes a Farmer. A Nitwit never will.

Villagers only harvest when the mob_griefing gamerule is on, which is the default. In a world with cheats, this turns it back on:

/gamerule mob_griefing true

When the farmer carries more than 24 food points (Bread counts 4, a Carrot or a Potato 1), it throws half a stack, 24 items at most, to a villager standing within about 2 blocks. Thrown items cannot be picked up for half a second; a hopper grabs them first.

1. Right outside the fence, in the middle of one side, dig a hole 2 blocks deep.
2. Put a Chest at the bottom, then sneak and place a Hopper on top of it. The top of the hopper is now level with the farmland.
3. Put a second villager on the hopper and close the three other sides of the cell with solid blocks, 2 high. The fence stops it from walking out but not from seeing the farmer.

Keep beds away from the farm, or the two villagers will breed. On Bedrock Edition farmers also harvest and replant, but test the collection on a small scale first. For iron, the same villagers can run an iron farm.