Q. We have several firebushes whose leaves never turn that spectacular red in the fall. They just remain green until they fall off. We have fed them spring and fall, and yet there are several other firebushes, treated the same, whose leaves do change color. Any suggestions? J.L., Terre Haute, Indiana
A. Fall color or lack thereof is affected by a number of factors, including genetics of the plant and environmental conditions such as temperature, soil moisture and sunlight. While nutrition certainly also contributes, it sounds like you have some plants that lack the genetic disposition for good fall color. This is not likely to improve over time.
Aronia (chokeberry) fall color and fruit.
Photos courtesy Purdue University Arboretum
Firebush, or burning bush, is considered an invasive plant in Indiana, so you might consider replacing these with one or more of the following alternative shrubs with attractive fall color. Look for cultivars that are noted for good fall color at your garden center. You can take a “tour” of these plants and more at the Purdue Arboretum Explorer website,http://mlp.arboretum.purdue.edu/.
Common Name Botanical Name
Bottlebrush Buckeye Aesculus
Chokeberry Aronia
Beautyberry Callicarpa
Redroot Ceanothus
Red- or yellow-twig dogwood Cornus
Leatherwood Dirca
Fothergilla fall color
Fothergilla Fothergilla
Witchhazel Hamamelis
Oakleaf Hydrangea Hydrangea quercifolia
Sweetspire Itea
Sumac Rhus
Viburnum Viburnum
Q. I have a small garden with nothing but tomato plants and cucumbers. I put pine bark mulch on it to control the weeds. I was wondering if I should till the pine in or rake it out. R.W., Terre Haute, Indiana
Oakleaf hydrangea fall color
A. Pine bark is relatively slow to decompose and may make tilling more difficult. So it may be best to rake the mulch off to the side before tilling. The bark mulch could then be reapplied after planting next season. Or you might consider using the pine bark in your landscape beds around trees, shrubs or perennial flowers or between beds, if you use raised beds. Finer-textured mulch, such as clean hay, straw, grass clippings, dry tree leaves (except black walnut) or pine needles, can be tilled under in the garden.