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Sunday, June 1, 2014

Vitex Water Management Affects Blooms and Growth

Q. I have a Chaste tree that has been growing in my backyard for about seven years.  The branches have always been full of leaves and I would get an abundance of beautiful purple blooms. Last spring, I noticed there were not as many leaves and I would only get purple flowers here and there. This spring again the leaves are sparse and the branches are mostly bare. Should I be doing something extra to bring back the lushness of my Chaste tree?

A. Vitex, or chaste tree, is relatively pest free. It originates from the Mediterranean region where the summers are usually hot and dry and the winters cool to cold and wet.
Vitex in winter
            The only real problems the plant has are if the roots remain too wet or the plant doesn’t get enough water. So my reaction to your question was concern about your irrigation practices; either watering it too often or not giving it enough water when you do irrigate.
            Both could cause similar problems. If the roots stay too wet, root rots develop and you might see a thinning of the canopy and branches dying back. Watering too often results in poor growth or worse. If overwatering continues, you would probably see dieback in the tree and eventual death from root rots.
            If the plant does not receive enough water, the plant canopy will begin to thin out and along with that a reduction in blooms.  If you feel like this tree does not get much water then try flooding the area around the tree once a week in conjunction with your irrigations. If the problem is not enough water, you should see a reaction to additional applied water in 3 to 4 weeks.
Vitex in bloom
            It also will do best with irrigations similar to other most of your landscape or fruit trees. This means regular deep irrigations.
            Avoid daily irrigations. Water about twice a week during the hot summer months. In the spring and fall months, water deeply and thoroughly once in a week. As temperatures cool towards winter, you would probably irrigate deeply every 10 to 14 days.

14 comments:

  1. From the reader sent to me by email:
    Hi Robert,
    We emailed each other this late spring regarding my Chaste Tree. It was not blooming and there were very few leaves on it.
    Well, after hand watering it several times each week, like you suggested, it has finally come back and made many beautiful blooms these past weeks!
    Thank you for helping me resolve this problem!
    I look forward to more of your great blogs

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  2. Mine has a ton of leaves but are completely wilted like they are melting....not sure what to do..

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    1. Not sure what to tell you besides either not enough water or too much. Water during the summer no more than three times a week. My guess it is not enough water applied when you do water. That has been a common problem with homeowners with some plants during this heat. Try an experiment. Take your hose and apply about 15 to 20 gallons to the base of the plant slowly so it soaks in and see if the vitex perks up. If it does then you know you arent applying enough water and add more drip emitters if it is on drip. As trees get larger they require more water. That can only be done by adding more emitters. Adding more minutes to the station applies more water to EVERYTHING on that station which is not needed if this is the only plant not getting enough.

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    2. If doing the soil test around the base of the tree shows the soil 6 inches or deeper is moist but the leaves are wilted and some of the tips are dark brown and crispy, does that mean it's overwatered?

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    3. You are missing one piece of valuable information. Overwatering can come from water too often OR giving the plant too much water when you irrigate. Are you watering daily or are you watering less often? A vitex is considered a small tree. That means every time you water, you will make sure the water wets the roots 18 inches deep. That is the purpose of a long steel rod like rebar. Rebar is used to judge how deep water is going in the soil after an application. Once that is known, the time needed to water that tree is always the same. The next component to an irrigation is when. That is judged with a soil moisture meter pushed into the soil in three places under the tree to about 4 inches deep. When the meter reads midway, (a 5 on most meters) its time to water again. Once you find out how much to give a tree and how often the only thing that changes through the seasons is how often. Always give trees at least one day of no watering so they can "breathe". Thats what is meant when people say...water trees deep and infrequently.

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    4. Thanks for the information. I will buy a soil moisture monitor right from Amazon right away. I see one that measure Moisture, Light, and pH. The landscaper had the schedule set to daily at 15 minutes each time. I read about watering less frequently but deeper so I changed it to weekly to 2.5 Hours. After the first 2.5-hour watering, I noticed the leaves started wilting. The tree has not been watered for 4 days now. I poked some holes around the base to let the moisture in the soil evaporate faster. I hope I am doing the right thing. On the other hand, I have a Raywood Ash that was planted the exact same day and it's been receiving the same amount of water but it is looking great!

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    5. How deep to water depends on the size of the tree. The mature ash is a larger tree and should get watered about 24 inches deep. The mature vitex is smaller so it is watered only about 18 inches deep. What is important is WHEN they get water. They both are fine on the same valve (when to water). They can get water at the same time. what is different is the size of the emitters and/or the number of emitters under each tree. The size and number of emitters determines the amount the trees get. Getting water at the same time (same valve or station on the controller) determines WHEN the trees get water. If one tree is sizably larger (now) then it should get more water (more and/or larger emitters). Emitters should be distributed under the tree canopy AT LEAST half the area under it. watering all the area under the canopy is ideal but seldom done or is it very realistic unless small trees. Emitters should be 18 inches apart under the canopy and start about 12 to 18 inches from the tree trunk. I use drip tubing in a spiral around the trunk and gauge the number of emitters to the time allotted for irrigation. If you end the loop under the tree then you should flush this line periodically. So I loop it back into the line that provides the water in a continuous loop. Then there is no flushing needed.

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  3. Help! Just bought two Vitex
    . Love them! But a small sprinkler was accidentally left on overnight on one and it looks slightly wilted. What do I do?

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    1. Sorry for the late response. All you can do is wait for the soil to dry out and see what happens. It will dry out faster if you can punch some vertical holes a few inches in diameter under the canopy. The easiest way to do this is using a posthole digger down to about two to three feet. A more permanent solution is to then fill these holes with gravel to help keep them open. Basically French drains.

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  4. I've been researching about the difference of symptoms between overwatering and underwatering Vitex trees. Unfortunately, I've read that the symptoms are very similar so I am now more confused than when I started. I had one planted a few weeks ago. The first week the tree seemed to be OK. This week I noticed the leaves started drooping / wilting. There are also leaves that turn yellow and some turn yellow and the tip and sides are dark brown and crispy. I checked the surrounding soil by inserting a long screwdriver into the ground and it went through easily and the soil attached to the screwdriver was somewhat moist. Based on my research, this means it is being overwatered but I am not sure. I already changed the watering schedule so that it doesn't get watered for a week. Is this the right thing to do? Also, how often should I water this newly planted Vitex tree and how much? There are 3 emitters on it. It is only about 4-5 tall (small one). I live in AZ. Thank you!

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  5. My Chaste tree bloomed beautiful once in early spring. But nothing since, Now it just has what looks like seeds where the blooms were. Do I need to cut the spent spikes off...Thanks for your help in advance.

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  6. My Chaste tree bloomed beautiful once in early spring. But nothing since, Now it just has what looks like seeds where the blooms were. Do I need to cut the spent spikes off...Thanks for your help in advance.

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    1. Vitex will do that. The flowers turn to seed and some think it is unsightly. If you do, cut them off but not necessary. Vitex isn't a desert tree but mesic and grows very nicely in the heat of the desert if it gets watered. Make sure it gets lots of water the month prior to flowering and the flowers will be spectacular. The rest of the year just water it as you would any other plant in your landscape. Vitex has become a weed problem in wetter climates than the desert.

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  7. I have three Vitex trees one has long flowers about 5 -6 inches long the other two have flowers that look stunted only about 2 inches long. Why?

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