Bottletree New Growth Dying in Phoenix

Q. The new growth on my bottletree I bought in 2018 is dying (crusty), starting a month or so ago. After talking to the local nursery, I increased the watering and soaked it for about an hour and it now looks worse. I’m watering 6 days a week and each time the tree is getting 22 gallons.

Branch in bottletree dying back.

A. Not sure why you thought the tree looked worse after you watered it. This trees roots are sensitive to watering often and keeping the soil wet. It’s a “deserty” kind of tree, but not truly “deserty”. As a young tree, it needs about 20 – 30 gallons each time it is watered. You are watering the right amount, but the soil shouldn’t be continuously wet six days a week. That’s a mistake. Read what someone else says about this tree in the Phoenix area.

Roots Must Breathe

The roots need a chance to “breathe” after the tree is watered. Knowledgeable people from the Phoenix area suggest watering this tree only twice a month during the summer. Remember, Phoenix is a bit wetter than we are because of their summer monsoons and they get more cloud cover.

My advice is not as dramatic, but I think not giving the soil a chance to dry out between irrigations is a mistake with this tree. Starting this October, try watering less often, maybe twice a week. Apply water to the soil starting 12 to 18 inches from the trunk. This water should wet the soil all the way to the ends of its branches (canopy). This tree likes to have other smaller “deserty” plants getting water near it. Other plants help cool things down.

Apply Water Less Often but Deeper

Apply enough water so the soil is wet to a depth of about 24 inches. This takes somewhere between one and 2 inches of water so that will take about an hour or so. Then hold off on your next water application until the top four or five inches of soil starts to dry out. Then water again. This might result in watering once, twice or three times a week depending on the time of year. Watering fills the soil again with water and then wait long enough for the tree use it. The upper surface of the soil will begin to dry. This drying of the soil encourages deeper rooting of the tree and helps avoid root diseases due to frequent watering. That’s normal.

Inexpensive soil moisture sensor you can buy at any box store

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            Use an inexpensive soil moisture sensor (like the kind sold for houseplants) and gently push it to into the soil about 4 to 5 inches deep, soon after an irrigation and in several other spots. When the soil moisture averages about “5” on its meter, water again and fill up the soil.

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