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Some Like It
Hot!!
"Hot enough for you?" |
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“Hot enough for you?” seems to
be the question of the week. For most humans in
Wyobraska this past week the answer seems to be an
emphatic, “Sure is!” But there’s a rather
surprising phenomenon going on in Wyobraska
landscapes in recent weeks—as the human occupants of
those landscapes wilt in the heat and escape indoors
to air conditioning, many plants seem to actually be
relishing the heat.
We hear a lot about the plants that are struggling
and declining as a result of what appears to be
consistently warmer summertime temperatures, and I
will admit to having been more on the lookout for
plants that are suffering from the heat in recent
weeks. |
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The “continuous growth” trees likewise appear to be
ahead of schedule in terms of the length of new
growth, and surprisingly, the size and density of
leaves on that new growth. When a tree is
experiencing heat stress, its first response is to
reduce its foliage density by cutting off some of
its less productive leaves—usually leaves closest to
the trunk on the “inside” of the tree. But there
appears to be very little of this kind of heat
stress occurring in shade trees around the region
this summer. And the continuously growing trees,
like honeylocust and cottonwood continue to add
shoot length and new leaves, as if to say, “ain’t
this heat great.” (They’re trees, not English
majors.)
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Previous Articles
Fractions March 15
Yardner March 8
Urban
Legends of Trees March 22
Que
Serra, Serra March 29
Grocery Store or Garbage Dumpster Plants April 5
Planning Your Landscape Project April 12
Planting
Cool Trees April 19
Keeping
Trees Alive April 26
Thrillers, Chillers, Spillers May 03
Will
You Still Love Them May 10
Ornamental Grasses May 17
In
Memory of Cedar Trees May 24
Gardening is not Childs Play
Versatile
Viburnums June 6
Yardner Plants
June 13
2007
Garden Walk and
Blue Spruce Decline
The Birds
& Bees of Butterfly Gardening June 28
Summer
Landscaping July 5
Cutting Your Lawn Down to Size July 12
2006 Articles |
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.A few weeks ago in this
column I wrote about significant problems with
Colorado spruce and white birch apparently related
to the region’s prolonged drought and higher than
normal summer heat. But over the past couple of
weeks it has become almost impossible to overlook
the fact that a lot of landscape plants,
particularly trees, are looking healthier than
ever. And I have come to the simple conclusion
that “some like it hot.”
Shade trees seem to be
particularly pleased with the new, warmer, Wyobraska
summers. Autumn purple ash, a popular shade tree
because of it’s orange-purple fall foliage, seems to
have extra luxuriant foliage this summer. But what
is even more striking is that the foliage is
flourishing in the heat, not faltering, as one might
expect.
Some trees, like cottonwoods, honeylocust, and
maples, grow continuously through the summer growing
season, but oaks grow in spurts. Bur oak, a widely
planted shade tree grows in two spurts—one which
occurs in spring as the tree leafs out, and the
second in mid-summer. Historically bur oaks in
growing in western Nebraska have put on their second
growth spurt in late July. But this year I noticed
several bur oak trees shooting that second spurt of
growth before the 4th of July.
Presumably, it will be a significant advantage to
these trees to have that extra layer of leaves
functioning for a longer period of time through the
growing season—the equivalent to the tree of raise
in its paycheck.
New Growth on Burr Oak |
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To be sure, the trees that are thriving are all
growing in well-irrigated settings. Water is
essential for growth, not only because the movement
of water and fluids through the tree drives its
circulatory system, but also because water is a
plants only source of hydrogen atoms. That’s
important because plant tissues are made up of
molecules that have four main ingredients—carbon and
oxygen (which plants get mostly from the air),
nitrogen (which plants get mostly from the soil, and
which is why fertilizing with nitrogen can stimulate
plant growth) and hydrogen (which plants gets from
water). By the way, normal lawn watering of 1.5 to
2 inches per week is adequate to meet the needs of
most Wyobraska shade trees.
Warm season turf and ornamental
grasses are also thriving. Look for more of the
miscanthus cultivars, like zebra grass, flame grass,
and silver feather grass to form seed heads this
year in Wyobraska landscapes simply because the
extra heat will speed up their seasonal growth
cycle. Likewise, the popular hardy pampas grass
will likely be earlier to form its seed heads this
year, and most clumps will likely be even taller
than in past years. By the way, a little extra
water will definitely push both miscanthus and hardy
pampas grass to grow a little faster and bigger.
Likewise, warm season turf
grasses like buffalo grass and blue grama also are
liking the heat. They particularly like the longer
warm growing season or recent years, and the warmer
nighttime temperatures. Their “green season” now
extends from early May through September. It’s
still not the April to November green lawn of
bluegrass, but the drought tolerance of these warm
season turfgrass has more and more Wyobraska
homeowners considering them as options for lawn
grasses.
“Hot enough for you?” Here’s a
suggestion. Beat the heat for the next few weeks by
sitting under one of those faster growing shade
trees in your yard and sipping the beverage of your
choice.
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