February 2020
Pickaway
Gardener
Accumulation
By Paul Hang
This is not a
weather forecast. It is not a weight loss add. It is neither about snow or
pounds but heat. Not weather or weight but about warmth and its accumulation in
Nature. We all accumulate days, until we don’t. Some of us accumulate wealth,
some lose it, and some don’t accumulate it at all. Trees accumulate girth, as
do some of us. However, trees don’t lose their girth as do some of us. What I want
to consider is the kind of accumulation that can’t be reversed. Most things can
accumulate heat but lose it. Just go out this month without a coat and feel.
A discovery
in the plant world has revealed that perennial plants, and insects, behave
according to accumulated heat. Using a formula (engineering types can, as my
Mom used to say, “look it up on the Google machine.”) that, beginning on
January 1st, counts the amount of the air temperature above 50
degrees each day and how long it stays there, you can calculate something
called a Degree Day (DD). Degree Day is
a measure of the amount of heat the earth, at any one location, absorbs and
accumulates when the temperature is over 50 degrees. Degree Day also measures
the growth and development of plants and insects and it is directly related to
the daily maximum and minimum temperature. The value of DD is cumulative. As
the days get warmer, the DD value increases. A cold spell will slow down or
even stop the increase in the DD value: but never reverse it. A hot spell will
speed up the accumulation of the DD value.
As an
example, Silver Maples first bloom at 34 degree days and full bloom at 42. As I
write this (mid-February) the DD value is 31 and the temperature is 46 degrees.
I predict that Silver Maples around me will begin to bloom today if the
temperature gets to 50 degrees for a few hours!
Scientists
have also correlated the hatching of insects with DD. Thus we know when
Bradford Callery pear first blooms (DD 142) the European Sawfly eggs hatch (DD
144). We also know that when those much rightfully maligned Bradford Pears
bloom it is time to put down pre-emergents because crabgrass won’t be far
behind.
The science
of this is called phenology, the correlation of natural events with one
another. (Phrenology is the discredited study of the bumps on our heads.) Here
in Ohio you can access the Phenology calendar at ww.oarwdc.ohio-state.edu/gdd. This site will ask for your Ohio zip
code. It will then tell you what the present value is of growing degree days
and the corresponding plant that is in bloom.
This
information is the result of research which was carried on across Ohio in the
past, a lot of it by Master Gardener Volunteers who recorded the dates when
certain plants bloomed in their area. Pickaway County has a Phenology Garden of
indicator plants in Five Points which is maintained by Master Gardener
Volunteers. You have now accumulated knowledge and a tool that will give you
power. Use it wisely.
Things to do in the garden:
Not much.
Check perennials for heaving up out of the ground. Press them down gently with
your foot. Send in your seed orders. Will our results ever match those of the
glossy color pictures? When you make out your seed and plant orders consider
planting more native and heirloom plants and vegetables. Native plants are
plants that evolved here and are adapted to our conditions, diseases and native
pests. While you’re at it try googling the name of a flower you’re thinking
about ordering. You will be able to see
pictures and planting information.
This is the
time to prune trees and shrubs (after you sharpen your tools). You can see
their structure now that they are dormant and the leaves are down. Cut out
crossing and rubbing branches and unwanted suckers. Pruning can be done to reduce the size of a
tree or shrub to bring it in to balance or to remove overhanging branches
blocking a view or path. Remember, spring flowering shrubs should be pruned
after flowering if you want to enjoy the blooms. Insects are less likely to be
attracted to cuts while trees are dormant.
On smaller
trees you may want to take care of problems yourself. On larger trees you
should call in an expert to inspect and perhaps correct any problems. Arborists
are in a slow time of year. The ground, if frozen, will not be damaged and
compacted as much from equipment and crews. The Arbor Day Foundation recommends
that you have Certified Arborists check any safety problems you may have
noticed. To find them go to www.isa-arbor.com click on “Verify Certification” and
then “Find an Arborist.”
If you dug up
bulbs for storage check on them. Spritz them with water to prevent drying out. Throw
away any rotting or shriveled ones. Water any dormant or overwintering plants
in your garage or basement.
Some seeds
can be started indoors this month for setting out in late March or early April,
depending on the weather: onions, cabbage, cauliflower, and other members of
the Cole family. The University of Minnesota has a good discussion; go to www.extension.umn.edu/garden /flowers/starting-seeds-indoors. Also
Google Winter Sowing. There you will read how to use old plastic milk bottles
to easily germinate some seeds especially onions. It is also a good way to
raise a lot of seedlings for planting “drifts,” those bands of like plants that
wander serpentine through our flower beds.
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