How often do actual forests need watering by humans?
The same goes for your food forest.
You see, the magic is in the mulch. Wood chips will keep the soil moist even in the heat of summer when it hasn’t rained for a while. Start digging down and you’ll feel the soil start to get moist after a few inches.
This is essentially “watering from the bottom,” rather than from the top. The great thing about this is that it allows oxygen to reach the roots. If you were manually watering your plants all the time or using an irrigation system, then you’d reduce the amount of air pockets in the upper layer of soil.
There’s also common fungal diseases such as “damping off,” which typically affects seedlings that are watered too much. In a self-propagating food forest, the absolute last thing you want is to kill your newly sprouted seedlings for the sake of watering your mature crops.
The bottom line is: manual watering and irrigation systems are not needed at all, and can even cause damage to your crops.
With at least 3-4 inches of wood chips as ground cover throughout your food forest, you’ll be able to emulate the moisture-retaining action of an actual forest floor, which not only negates the need for manual watering, but also builds and enriches your soil over time.
Just make sure you’re using the right kind of wood chips. You’re looking for more of an 80% green, organic matter content to 20% brown, woody content. You can get this stuff for free by asking a local tree service. The smaller branches they trim are far more “green” than chipped up heartwood is, so it ends up about right.
However, having said all this, you’ll need to water seedlings and trees when you transplant them. It really helps settle them into their new home.
Also, in the first couple of years before your soil is built up with organic matter, you’ll need to water your food forest whenever there’s an drought, like when there’s over a month of no rain. The moisture-preserving qualities of your wood chip mulch layer is going to be what keeps your plants alive during very dry periods like that.
Avoid bare soil. Exposed soil dries out so quickly, which is why watering and irrigation systems are so common in traditional farms. Mulch eliminates the need for watering in anywhere other than the most arid of climates.
Hot, Arid Climates
If you’re living in an arid climate, then the best thing to do would be to take inspiration from the greener areas in your local climate.
While it might be too dry for full forests to form, you’ll notice that where the soil is most protected, plants of different heights are able to thrive pretty close together.
Invest heavily in your ground cover, and avoid plants which can’t handle the heat. While an arid climate might seem to be a curse, it’s actually a blessing once your food forest is established.
With all this in place, you’ll minimize the amount of irrigation that you’ll need. You’ll still need an irrigation system, but your food forest will retain that water you feed it really well.
Besides, in an arid climate,.you get to enjoy tomatoes being perennial where you live. A lot of growers are jealous of that.