IC2 Crops Guide

This page contains a guide to progress through IC2 crops and take advantage of the many kinds of renewable resources they provide. For a list of crops, see IC2 Crops List, and to read about crop mechanics in more detail, see IC2 Crops.

Crop breeding can be started in the Steam age, but it becomes much faster and easier with the Portable Scanner, which requires HV circuits.

TL:DR

Begin by crafting IC2 Cropsticks and searching for Sugar Canes in the world. When you have some, right-click wet, tilled soil with the sticks to put them down (wet soil makes the crops grow faster).
Right-click the cropsticks with the canes to plant them. This creates Reeds, the name of the plant that ended up in the cropstick.
Wait for the crop to grow fully and right-click it to get some more Sugar Canes.
Place down some more Cropsticks. Put two of them on the same dirt block to make double cropsticks, surround it with Reeds and put more double cropsticks on the corners to make a 3x3 field. The double cropsticks allow for the crossbreeding of the Reeds, originating more of themselves or a different kind of plant at random.
Watch out for weeds! They can show up in cropsticks without a crop inside (double cropsticks too), and if they are allowed to grow, they take over adjacent cropsticks and replace the plants inside. Destroy the cropstick if a weed appears, right click with a Spade or use Weed-Ex to prevent the weeds from appearing for a good while.
Make more of these 3x3 fields, or expand the first one, alternating between Reed and double cropstick. Keep doing this until you get Stickreed. Be careful that Stickreed is different from Reed, but looks the same in the first three growth stages! Use a Plant Lens to see what crop it is, or a Portable Scanner if you have it.
Keep crossbreeding until you have a lot of Stickreeds, and replace the Reeds you had with those. The objective now is to crossbreed them to get better crop stats.
To see crop stats, the early option is an LV scanner, but it needs harvested seeds to scan, which needs the crop to be fully harvested as well. To avoid this, make a Portable Scanner and right click planted crops to see their stats right away.
Crop stats start at 1/1/1 for Growth/Gain/Resistance and change slightly from the existing crops to the new one, at random. Since Stickreeds grow very fast and are Tier 4, unlike most of the other fast-growing crops at Tier 1, keep crossbreeding and replanting the new crops that have better stats than the ones you have. The objective is to get 21/31/0 for Stickreeds used to spread high stats to other crops, and 23/31/0 for crops meant to be harvested in an automated farm.
While crossbreeding for stats, pick all the different crops that show up over time and store their seeds. To reach most of the useful high-tier crops, start with the ore crops obtained from crossbreeding Stickreeds and cross those, aiming for higher and higher tier crops until you reach Platina. These need Platinum Blocks to grow fully, which might be unavailable, but they can still crossbreed without the block at growth stage 3.
When both steps are done, crossbreed the max-statted Stickreeds with other crops to transfer over the high stats. To obtain other kinds of crops that haven't showed up yet, the NEI tab on the seeds is useful and a good path to follow.

Automating

All IC2 crops can be automatically harvested for their resources when they reach their final growth stage, and return to an earlier stage without needing to be replanted. Instead of doing it all by hand, it is possible to use a singleblock (Crop Harvester) at LV, or a multiblock (Multifarm) at HV to harvest crops for you.

The Crop Harvester is often paired with another singleblock, the Crop-Matron, which automatically uses water, Fertilizer and Weed-Ex on all crops within a 9x9 square centered on it. The Harvester has a slightly bigger range, 11x11, and only does the harvesting. They each use 1 LV amp to run continuously, and together they need 2 amps to keep all crops growing fast and harvested automatically, but they're cheaper to craft than the alternative if you only need a small farm to automate a handful of crops, and available at earlier tiers than the Multifarm is.

The Multifarm is the multiblock option that does all of watering, fertilizing and harvesting at the same time, but has no slot for Weed-Ex. It is a multi of variable size, from 3x3x4 to 5x5x4 (LxWxH), and the available area for the farm depends on the its size, with the largest one being recommended to extend the farm as far as it can go, given it is a cheap build at HV, the stage where you normally unlock the ability to craft the Uranium Electron Tubes that change the Multifarm mode to IC2 Crops.

The size of the farm for a max-size multiblock is organized as such, being able to cover 1149 potential crops, or 1136 with the water holes:

Diagram of the Multifarm size. The dark green squares in the center are where the multiblock is, the green squares are the size of the multifarm in other modes, and the light green squares show the full size in IC2 crop mode.
Screenshot of a built Multifarm at its max size, with the best layout for water blocks to hydrate the dirt.

It's worth it to note that space for crops has to be sacrificed to add water blocks, but the growth boost that high-statted crops receive from the hydration far outweighs the lost tiles.