Thursday, April 23, 2020

Accumulation


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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