transplanting crape myrtles redux

terratoma(7a)June 17, 2013

I have two crape myrtles that require transplanting for a sunnier exposure. (I've searched various forums in GW and read widely different opinions. Am interested in the current thinking on the subject.) : )
I bought the two in containers and planted last fall. Both are doing well: 'Tonto' has grown to 4' with a 3' width (canopy); 'Catawba' is 6' x 4'.
1. When is the best time to transplant? (I'm not concerned with any additional watering needs or loss of flowers if I transplant now. My only interest lies in the health of the plants: I don't want to stress them.)
2. How far should I expect the roots to have extended?
3. How much of these roots do I need to retain when I transplant? IOW, how large of a root ball should I expect to have to dig when moving them? (How far out from the trunk and how deep?)
4. I've read suggestions about root pruning the trees in preparation for transplanting. Is this advisable? If so, I'd be most appreciative if some of you would walk me through the specific steps of this procedure.
Truth be told, I'd be equally appreciative for any help about any facet of transplanting crape myrtles.

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ken_adrian Adrian MI cold Z5

root pruning is very old school ...

current thought is not to stress the heck out of them now.. and do it again at transplant ... when the time comes.. just do it ...

we are only a few weeks from the high heat of summer... in my z5 MI ... i am basically stopping all transplanting.. and holding stock over until fall ...

you would dig about 6 inches out.. from what you planted ...

if you tell us where you are.. someone might be more specific on dates ...

if you have to move them.. just do it ... but my suggestions is for the best time to move them ...


    Bookmark   June 17, 2013 at 2:10PM
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Thanks for the suggestions. I'm just outside Roanoke, VA. Despite the mild weather thus far, history tells me we're in for some blistering hot days through July and August. (And September hasn't been exactly comfortable as of late.)
I usually do dividing and transplanting of perennials (hostas, for instance) in late September to mid-October.
The crape myrtle's planting containers were about 12" in diameter; the planting hole I dug was 24" wide and as deep as the container. (Actually, not quite as deep since I planted them just a bit 'high'.) Please bear with me: I want to make sure that I understand. You suggest digging 6" out from what was planted. If I go out 6" from the base of the trunk, I'll have a root ball the same size as it was in the original container. If I go out 6" from the original root ball (as it was in the container), I'll have a root ball about 24" in diameter. Of course, If I go out 6" beyond the planting hole I dug, I'm looking at a diameter of 36". Big hole! : ) I'm a bit slow sometimes; would appreciate if you'd clarify which of my interpretations is correct.

    Bookmark   June 17, 2013 at 3:13PM
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Ken, can you explain why root pruning is old school? Everything I've read from extension services has said that it improves survival rate after transplantation, especially when you can't provide adequate watering.

    Bookmark   June 17, 2013 at 4:59PM
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brandon7 TN_zone(7)

1. I believe this link will answer your first question: Planting a Tree or Shrub

2. & 3. Crape myrtles are tough and need very little babying. You can add trunk diameters (if multiple trunks) and get a rough idea of the rootball size from the table found here: Generic Rootball Size Guide

4. Root pruning is not necessary for crape myrtles. It might be beneficial for some much more finicky types of trees/shrubs, if you could do it far enough in advance. I see no benefit in the case of crape myrtles.

    Bookmark   June 17, 2013 at 10:02PM
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Dave in NoVA • 7a • Northern VA

I would have transplanted the crapes in March or April prior to their coming out of dormancy for the best outcome.

But, since yours have not been in the ground all that long (and probably are not really established yet), you could probably get away with moving them now PROVIDED you trimmed back some of the new growth (maybe 2/3 of the NEW growth?) and water, water, water them all summer, deeply at least once a week.

    Bookmark   June 18, 2013 at 10:05AM
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Thanks everyone.
I've calculated the rootball diameter and depth for transplanting, using the guide provided by brandon7 earlier in this thread and will be listing the results.
But first .....
yesterday,a neighbor heard about my plans and said that I don't need to transplant. According to him, the crape myrtles are getting 'all the sun they need'. Being new to crape myrtles, I have no basis to disagree with him. I'd like to get your take on the situation.

'Tonto', the smaller of the two, gets full sun until about 2PM, daylight savings time(so actually 1PM based on the sun). By 3PM (true 2PM), it's receiving no direct sun. Is this, as my neighbor claims, sufficient sun for the crape myrtle to thrive and bloom? I was under the impression that they were sun lovers and needed all day or near all day sun.

    Bookmark   June 19, 2013 at 3:21PM
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brandon7 TN_zone(7)

I believe they would probably do better and be healthier and more full if given more sun. Whether or not they will have "enough" sun exposure in their current location, it's hard to say. My guess is that they would survive with the light they have now, but not not reach their full potential.

Do NOT "(trim) back some of the new growth" if you do move them!

    Bookmark   June 19, 2013 at 10:21PM
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After all the responses, I am leaning toward transplanting (for more sun) in the fall. I understand transplanting now is a possibility but am concerned about the stress the plant may experience during the summer.

brandon7: I used the rootball guide you kindly provided and calculated the diameter and depth of the rootball I will need to dig when transplanting. I'd appreciate it if you would look over my figures to see if my interpretation is correct.
(Both crape myrtles have three trunks coming out of the ground close together. I calculated the diameter with C = d x pi)
1. 'Tonto': The diameter of the three trunks are .68", .6" and .52", respectively. These add to a 'total trunk diameter' (that's what I'll call it for these purposes) of 1.8". Based on the guide, I'll need to dig a rootball whose diameter is 25" and depth is about 12".
2. 'Catawba': Trunk diameters are .83", .83" and .64", respectively, resulting in a 'total trunk diameter' of 2.3". According to the guide, I should dig a rootball with a 32" diameter and a depth of approximately 14".
Are these figures in the ballpark?

    Bookmark   June 20, 2013 at 7:58PM
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brandon7 TN_zone(7)

Yes, you did the calculations correctly. These are just rough estimates (and may not be ideal for all species), but should work great for your crape myrtles.

    Bookmark   June 20, 2013 at 8:56PM
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I would wait till they go dormant in the winter. They are pretty tough, but I'd still wait till dormant. Much less stress...

    Bookmark   June 24, 2013 at 2:53PM
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Back again. I decided, after reading the suggestions_ and no offense to anyone_ to wait until late September to transplant.
I'd appreciate any suggestions regarding pruning that should be done before transplanting. (I'd like to train the plants into a 'tree', rather than a 'shrub', form.)

    Bookmark   August 16, 2013 at 12:21PM
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ken_adrian Adrian MI cold Z5

why would you want to cut off all the branches.. before you cut off all the roots...

one stress this fall.. move it...

once re-established.. then start cutting off its food making machines.. the leaves ....


    Bookmark   August 16, 2013 at 5:10PM
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