IN THE GARDEN: What causes variegation?

Q Our Asian jasmine ground cover has become variegated this summer. It has never happened before in the 12 years that we've lived in this house. Any ideas?

A Variegation may be the result of a naturally occurring mutation in the plant that is called a chimera, or it can be a result of carefully engineered breeding, or it can be a result of a virus. Sometimes gardeners buy a variegated plant, and then it reverts back to its green coloration. The plant looks like it is still thriving, so enjoy the variegated color. Keep an eye on it, and if you see any problems, take a sample to your local nursery or county office of the University of Arkansas Division of Agriculture Cooperative Extension Service.

Q I have a young Southern magnolia tree that is now about 14 feet tall. Beautiful tree, but no blooms as of yet. I seem to remember that in a past column you said something about how long it might take for a young magnolia to bloom. Could you repeat that information, please?

A There are many varieties of Southern magnolias. The newer dwarf, or more compact, varieties bloom at a much younger age than the traditional large Southern magnolia, which can take eight to 10 years to begin blooming, while they establish themselves. Once they start blooming, you should be guaranteed blooms every year.

Q Clipped this from a small tree nearby. Smells wonderful ... want to plant one. What's it called? Any caveats?

A The plant in question is a vitex, or chaste tree. It is a wonderful small tree or large bush -- it tends to grow wider than it grows tall. Give it full sun and prune as needed before growth begins in the spring. It will bloom for eight weeks or longer in the summer, and bees and butterflies adore it. Purple is the most common color, but there are white-flowering forms as well. Many people mistake it for a large butterfly bush (buddleia), but the leaves are very different.

Q This is a redbud tree we planted in our yard in Benton when we first came back here from Mississippi. It was given to me at a garden show in Little Rock as a twig. I read something this spring that indicated the blooms growing directly on the trunk of the tree indicate it is rare.

A Many redbud trees produce flowers directly from their trunks as well as on their limbs. Trees that produce blooms directly on the trunk are referred to as "cauliflory." There are not many species that produce flowers/fruits on the trunk, so cauliflory species are rare, but it is not unusual to see flowers directly on the trunks of redbuds.

Q I hope you can identify this white flower. It's come up in my garden for a number of years. It spreads rapidly!! I call it my duck plant because of its shape. Thanks for any help you can give me.

A The plant in question is gooseneck loosestrife (Lysimachia clethroides). It is a prolific spreader, especially in moist areas. It has a long season of bloom, but it spreads quickly by rhizomes (underground roots). Much as with mint, if you want to prevent it from spreading, plant it in a container.

Q I usually have some of the prettiest and colorful hydrangeas in the neighborhood. It was always exciting to see what color they would be. I have always cut back at the right time, which I learned from you. This year I didn't have one bloom. My question is should I cut back the new growth or leave it? The plants are very green and healthy. Should I leave them as-is and hope next year they will perform again?

A The early hard freeze we had last October/November did a number on quite a few hydrangeas. Some gardens had severe damage, while others had little to no damage. It all comes down to the location, how cold the plant got and the variety. In my yard, only one plant out of four has any damage. There are quite a few reblooming hydrangea varieties now that may still set some late blooms. If your plants are too large for the location, then prune them, but if not, let them grow and maybe you will see some late, smaller blooms. Hopefully, we won't have a repeat of early cold like last year.

Retired after 38 years with the University of Arkansas Cooperative Extension Service, Janet Carson ranks among Arkansas' best known horticulture experts. Her blog is at

arkansasonline.com/planitjanet. Write to her at P.O. Box 2221, Little Rock, AR 72203 or email

jcarson@arkansasonline.com

The different types of Southern magnolias have varying juvenile periods before their first bloom.  (Special to the Democrat-Gazette/Janet B. Carson)
The different types of Southern magnolias have varying juvenile periods before their first bloom. (Special to the Democrat-Gazette/Janet B. Carson)
Vitex, or chaste tree, is a small tree or large bush that grows wider than it grows tall.  (Special to the Democrat-Gazette)
Vitex, or chaste tree, is a small tree or large bush that grows wider than it grows tall. (Special to the Democrat-Gazette)
Redbud trees are unusual among all plants for their habit of cauliflory — flowering on trunks and stems.   (Special to the Democrat-Gazette)
Redbud trees are unusual among all plants for their habit of cauliflory — flowering on trunks and stems. (Special to the Democrat-Gazette)
Gooseneck loosestrife (Lysimachia clethroides) spreads prolifically by rhizomes and will overrun a garden if not contained.  (Special to the Democrat-Gazette)
Gooseneck loosestrife (Lysimachia clethroides) spreads prolifically by rhizomes and will overrun a garden if not contained. (Special to the Democrat-Gazette)

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