We are installing drip irrigation for our large raised bed garden. The garden has perennials like berries, grapes, asparagus, and artichokes as well as the usual annuals like tomatoes, beets, squash, etc. so we have a variety of irrigation needs. We're trying to figure out things like appropriate water pressure, how long to run the system, how deep the water goes and how quickly. Those sorts of things. We're running 1/4" drip hose that drips every 6" off a 1/2" black hose. Most of the beds are 4'x8' and 2' tall. There are 3' wide beds running around the perimeter of the garden, each side being about 40' long. I'm wondering how wide the water will spread underground and how deep it goes before it begins spreading? How close does the line need to be to a plant and how far apart do the lines need to be? Will I need to water seeds planted straight into the ground by hand until the roots are deep enough to reach the moisture? How big will the seedlings need to be before they can reach the water? Is there a good book or resource we can read that will explain all these things? It's easy enough to set up a drip system, but a lot harder to understand what happens once the water hits the ground and how to make sure the plants are being watered correctly. Watering the perennials is easier as they're big and don't go anywhere. The annuals are much smaller and get moved around every year so we can't really have an emitter at every little plant. I also use succession planting and cover crops throughout the growing season so seeds are being planted all summer and into the fall.
Lane County Oregon
Parts of this question are out of my area of expertise I suggest that you contact a supplier of irrigation systems for the mechanics of installation..As to the movement of water, a lot depends on the texture of the soil. The general pattern is dependent on that. The line should be close to the plants and will generally not exceed a width of 12". The rate at which it penetrates the soil is totally dependent on the soil. In raised beds of good tilth and uniformity it is fairly quick.. Trial is the best way to determine this factor. Run the system for 1/2 hour, let set for 1/2 hour and dig down to determine your pattern of moisture. It is probably best to hand water seedlings until they are well-established. Your method of gardening is very good. Look into the different types of systems such as ooze drip lines, fan drip lines and individual emitters. Thank you for your patience.