Converting Peach Tree Irrigation from Twice a Day to Normal

Q. I have a well-established, prolific peach tree. About this time every year it loses some of it's immature fruit and I know that is normal. However, this year it's losing an abundance of fruit. I'm literally picking up 50-100 peaches a day. I have checked the irrigation and it seem to be fine with drippers at 15 minutes per day, twice a day.

A. This will be a challenge. Get ready for an irrigation overhaul! The usual reason for fruit drop is because the fruit was damaged in some way, either from a lack of water to the tree or cold temperatures that hurt the fruit. I don't think there were cold temperatures this late in the year, so I go back to the water issue.

Irrigation Twice a Day

I don’t like that you are applying water every day; twice a day in fact! Is there any way that can be changed to less often? That irrigation frequency sounds like watering a lawn or vegetable garden when its really hot and windy out! I don’t know about the amount you are applying, but you are applying water way too often.

Peach Tree Irrigation and Woodchips 

Fruit trees should have water applied to them twice a week right now and growing in most soils. The applied water should be enough so that the roots of the tree get wet to a depth of about 18 inches. For fruit trees growing in the desert, I like to see a layer of woodchips on the soil surface 3 to 4 inches deep. These woodchips provide a layer that protects the roots from getting too hot, conserves water, prevents most weeds from growing and helps keep the soil dark and rich.

This is an irrigation basin around a peach tree filling with water.

You are watering so often, unless you have very sandy soil, I imagine the tree roots  are growing about 2 inches deep. They should be growing 18 inches deep. Roots growing shallow like this are cycling back and forth between too dry, too hot or too wet. Roots can’t grow deeper because they are drowning (if you are watering a lot) or getting too hot and dry (if you aren’t watering enough).

Thirty minutes of water is meaningless to me. I need to know how many gallons you are applying and where it’s being applied.

What to do? 

This is tricky because the tree roots need encouragement to grow deeper and hot weather is already here. Root growth would be better starting in October when temperatures are cooler. Do not apply any more water using the current irrigation schedule of twice a day.

Free woodchips from local arborists who wanted a place to dump clean mulch.

Cover all the soil under the tree’s canopy with 3 to 4 inches of woodchips. Apply water to the soil 12 inches from the tree trunk all the way to the edge of the canopy. This can be done by constructing a donut around the tree trunk 6 to 8 feet in diameter.

Basin beneath grapes that didn't hold the water. It was repaired but easy to see!

The inside of this donut must be flat with a circular wall that is 3 to 4 inches tall. Fill the inside of this donut with a 1-inch layer of compost with woodchips on top. Fill the inside of this donut with water once a day. At the end of August, begin watering every other day. At the end of September water every third day. By December you should be watering once a week.

Rectangular basins with flat insides to hold water but let people and equipment through.

I generally figure that most peach trees that produce an abundance of fruit should only be allowed to keep about 1% or less of all the fruit produced by a tree. I'm assuming you are removing fruit that are closer than three or 4 inches apart all through the tree.

When peaches are pruned in the wintertime about half of all their branches are removed from the limbs. The removal of these branches are so that the remaining branches produces fewer fruit and there is less thinning to do. Otherwise there's a lot of limb breakage because of the weight of the peach fruit.