There is no set formula. My garden may require 2 hours a day every other day while yours in your zone may only need 1 hour a week.

It will be determined by several factors - your weather (temps, wind, rainfall, etc.), your soil and how well it drains or retains water, if your garden is mulched or not and how heavily, raised beds or in-ground, the length of hose you are using (it waters more at the hose connection end but much less toward the soaker hose end so shorter lengths work better), the diameter of the hose you are using, the water pressure you have, etc.

You'll have to do some experiments in your own garden to determine its needs. You can measure delivery rates by inserting several tuna or cat food cans into the soil so that the rim sits at soil level and run the hose over them. Time how long it takes to deliver 1" of water.

And the best way to check for the need to water is to check the soil moisture level several inches down at the root level. Stick your finger deep into the soil, don't go by the surface soil appearance as that cause most to waaayyy over-water their plants causing root rot and stunted growth.

Heavy mulching reduces water needs substantially and helps maintain consistent soil moisture levels - and that is the goal - so once the soil warms, naked soil should never be allowed in a garden. ;)

Dave

I use soaker hose for irrigation. It only rains in the winter here, and very little. Whether it rains or not, how often and long you water depends on the temperature. For cool weather no rain I water every other day (most vegetables) from 15 to 25 minutes. I water between 4 am and 6 am. I adjust the time and frequency by simply watching the plants and the soil they are in. I mulch heavily to save water and discourage weeds. In the dead of winter (now) I reduce the time a bit and if it rains I water just once a week unless it rains more often than once a week (yes, fat chance here...). In the heat of summer I have to set the system to water every day for about 25 minutes or so. I hope this gives you some guidelines to get you started, but as Dave said you will have to adjust by watching your garden and touching the dirt to see if it is too damp or too dry. You can also adjust the flow by using the ring they provide (makes a narrower opening). This works if you are using one irrigation line but different soaker hoses for plants that require different amounts of water.

Ditto the very good advice above. Let me add that sometimes you will see instructions such as "2 inches of water per week." The following might help:

Most vegetables and herbs demand soil that is moist to thriveÂnot too wet, not too dry. Most vegetables need 1½ to 3 inches of water each week to thrive. How much water is that? HereÂs a guide:

One gallon of water equals 231 cubic inches. One square foot in your garden is 144 square inches. Divide 231 by 144 = 0.62 gallons. A plant growing in about 1 square foot of soil needs a bit more than half a gallon of water a week to receive 1 inch of water.

A 4 foot x 8 foot planting bed = 32 square feet. Multiply 32 by 0.62 gallons = 20 gallons of water a week to water the bed to a depth of 1 inch.

How long does that mean you must water? That depends on the rate of water flow. Drip irrigation heads are pre-set to deliver varying gallons of water per minute. That is one way to measure the water your irrigation system delivers. Another is to place the hose or soaker hose in a gallon or 5 gallon bucket at the rate of flow you plan to use and simply time how long it takes to fill the gallon with water (divide by 5 if you use a 5-gallon bucket).

If all of this is too complicated, water your garden the old-fashioned way: keep an eye out for wilting on warm days and stick your finger in the soil. If you plunge your finger in the soil and it comes out wet and glistening, the soil is too wet. If your finger comes out dry, the soil is too dry. If your finger comes out damp but not glistening, the soil is probably just right, moist but not too wet.

When you water, be sure to keep the water off of the plants. Fungus and other diseases are easily spread one plant to the next on wet foliage. The best method for watering plants also involves the least work and the least use of water: drip irrigation. Drip irrigation which can include a system as simple as an inexpensive soaker hose may require some up front costs and labor but will carry you through several seasons with the least effort.

Here is a link that might be useful: HarvestToTable.com

I personally don't like soaker hoses. I found it hard to get enough water and to direct the water where I wanted it to go. For instance, a big tomato plant or squash plant where the roots go out quite a distance from the plant.

I prefer drip irrigation. I like the adjustable spray things. I set 2 or 3 around a big plant and can really soak the entire root system when I water. They are adjustable and easy to move around the garden as I rotate my crops and things change. I like the flexibility of the system.

Pretty easy to install too.

Julieann (or anybody else) - Do you have a layout for the drip irrigation you are using? List of materials, etc. My garden space this year is 2400 sq ft so I really need to watch my cost for set up.

Also, Mr. Drip sells commercial grade bulk soaker hose (500 foot rolls)and all the fittings as well as lots of drip stuff. Prices are reasonable. I have some of their hoses that are 7 years old and still work like a champ. (I do pick them up and store them in my barn in winter and I flush them good before using in the spring.) www.mrdrip.com