The Farmingskill is part of a system added to Project Zomboid in RC2.9. The player has the option of sowing seeds with a trowel to create a sustainable way to gather food. Farming is also influenced by the seasons system, meaning crops will yield more in summer than winter.
Increasing the farming skill provides more information about the crop status when the crop info is viewed (right-click -> Info).
At skill level 0, the player cannot discern much useful information about the crop they just planted, and rookie farmers have to rely on visual cues about the plant status. At a higher skill level more info is shown, including but not limited to: hydration level, growth phase, time left to reach the next growth phase, potential diseases types and plant infection levels for the diseases.
Increasing Farming Skill
You only gain farming skill XP when the player successfully harvests a crop they planted. No other actions (watering, checking, digging, or planting) give any farming XP.
The crop growth stages of Tomato plants
No matter how good you are at scavenging, eventually all of the food on the map will be exhausted. Once the power fails, a significant portion of the usable food will rot and become inedible. You cannot continue to survive without finding new, sustainable sources of food. Currently in Project Zomboid, you have four options: 1) Farming, 2) Fishing, 3) Foraging, and, 4) Trapping. Of these, farming requires the most work, but also appears to gives the most rewards. Combining your harvested crops with fish or trapped animals can make significant meals that will replenish hunger, thirst, and unhappiness simultaneously.
Step 1: Character Creation
This step can often be skipped, however choosing the right occupation and traits can rapidly increase the rate in which it takes to level up the farming skill. There is only one of each occupation and trait that will help with farming. The farmer occupation will give the player 3 farming skill levels, but it will also give an experience boost to that skill. This bonus cannot be gained after the character is created. This is the same for every major skill.
Starting Skill Level and Experience Boost
Level 0 - 25% (Default for all skills)
Level 1 - 75%
Level 2 - 100%
Level 3+ - 125%
Therefore, the farmer occupation will give a major advantage if the player wishes to live their life on a farm.
Zombies can trample your crops. This will damage or kill them.
You must plant in a place where zombies can't get to them while still allowing sunlight in.
One option is to build walls around the area you will plant in.
Another option is to plant on top of a second story where zombies cannot access easily.
To move dirt to your chosen location you need to have a shovel and sacks.
Equip the shovel in both hands
Put the sacks in your main inventory.
Right click on an area with dirt (grass is a safe bet, but there is only one layer of usable dirt per tile)
Click "Take some dirt -> Sack." Each sack can hold four (4) tiles of dirt.
Right click on the tile you want to drop the dirt on.
Click "Spill dirt -> Dirt bag."
Repeat until you have enough tiles for the amount of crops you want to plant.
Note: You may want to put space between your farming plots to prevent the spread of disease. See more about disease below. Alternatively you can treat diseases before they spread, without the need for spacing.
Remember to keep your crops in the "Well Watered" state. You will need to check them at least once per day unless it is raining. A watering can will speed up this process significantly.
If you're low on water, you will have to hope that it rains often enough to keep your crops watered. Placing Rain Collector Barrels around your garden to collect rain will be necessary to make sure you don't lose a harvest of crops and starve. Place them near your garden so you don't have to walk far to fill up your watering can. If you haven't got a high enough carpentry skill, a variety of water storage containers have a rain factor, which allows them to be filled when placed in the rain.
NOTE: Carrots and Radishes for the first phase need more water to start out. About 75 or 80 percent and then use the guide above for the rest of the phases.
Fertilizing your crops will help them grow more quickly. If you use NPK Fertilizer, it will remove 20 hours off of the current growth cycle of the plant. If there are less than 20 hours remaining on that growth cycle, it will immediately proceed to the next level and the extra hours will be lost. Generally, fertilizer is hard to come by for the large farms needed to sustain yourself, so it should only be used in an emergency to speed plant growth when food is getting scarce. Using too much fertilizer on a plant will kill it (4 or 5 uses).
Threats to Crops
Your immediate problem is the constant threat of zombies. Zombies can trample your crops and force your hard work (and water) into waste. Keep zombies away from your crops.
Zombies may go inside some of your nearly-grown crops and may try to ambush you.
Try to plant in a secure location and always check for zombies in your crops before turning your back to the crops.
Crawlers (the zombies that crawl on the ground rather than walk around) may go unseen in almost-fully grown crops.
Growing crops on patches with zombie blood causes the seedlings to become instantly "sickly".
There are currently three diseases in Project Zomboid: 1) Mildew, 2) Insects, and 3) Devil's Water Fungi (DWF)
These diseases will slow the growth of your plants, possibly kill them, and/or cause them to produce a smaller harvest than normal.
You can combat mildew and insects with a spray.
Devil's Water Fungi cannot be eliminated with a spray. Any tiles with DWF must be dug up and replanted to remove the disease.
Plants can be afflicted by the diseases listed above, and diseases can jump from plant to plant in close proximity. Strawberries have been reported to be particularly susceptible to disease. The best solutions to keeping disease to a minimum are to treat all infestations as soon as they appear, and to either grow strawberries in an area that is totally separate from your other plants (preferably enclosed within walls and a door), or not to grow strawberries at all.
Plant Disease Problems
Mildew causes your plants to mature more slowly than they would normally.
Insects cause a growing plant to consume more water. Affected plants will need considerably more water and attention than healthy plants.
Devil's Water Fungi (DWF) is arguably the biggest danger to your garden since it causes plants that are harvested to give smaller yields than healthy plants, and there is no countermeasure to fight it with, so it can quickly get out of control. DWF regularly occurs on plants that have been infected with either Mildew or Pest Flies for some time, so keep those two diseases under control and it should keep DWF to a minimum. Unless a plant is very close to harvesting, it is usually worth removing plants affected with DWF as soon as possible since the biggest threat is that of DWF spreading to your other plants.
Making Plant Disease Cures
As of Build 32, you either need the gardening trait or the farmer profession or you have to read The Farming Magazine to craft these items.
Note: Even rotten milk can be used to make Mildew Spray.
When you sow seeds to grow crops, a plant's starting health is determined by your Farming skill. The higher your skill, the higher the starting health. The health, as denoted as a percentage, increases slowly over time, unless affected by disease or inappropriate water levels. Currently, radishes and carrots have a maximum water level and thus can be overwatered, causing them to lose health. Thus, it is recommended to grow these crops in an indoors/roofed farm area, so that rain doesn't cause them to lose health from overwatering.
The health of a plant determines the size of the yield upon harvest. Seeds are given to the character when a plant is harvested during its seed-bearing phase; this is the last phase of a plant's life, and appears after the plant is able to be harvested solely for food.