I received a forwarded picture of a Bradford pear tree in full bloom last week in the yard of a former Vicksburger now out in the Dallas area. The question, of course, was “how come?” The tree owner stating that this tree always suffers worse than others nearby during prolonged dry spells makes the answer pretty easy. So why would a spring-bloomer like a Bradford pear bloom in late fall?
Because of rule no. 1 of all plants. The only mission any plant has is to reproduce itself for the survival of the species. No plant gives a hoot about you and me. Plants don’t care whether we see pretty blooms, eat fruit or vegetables, or have any plywood, cotton or turpentine. Again, plants merely want to make seeds; that’s it.
So what is a Bradford or any other tree to do if it “thinks” it might not live till spring? Hurry up and make seeds. The fall bloom in this case is due to stress from very dry soil, i.e. not enough water. Facing possible death the tree initiated seed production. And blooming is a step in that direction. Of course there is not enough time to make and mature seed before cold weather shuts things down, but a life-threatened tree is at least going to try.
Now, gardeners know a perennial early spring-blooming woody plant is supposed to get a certain amount of cold weather before it can bloom, right? Right. The process of cold-in-order-to-bloom is known as “vernalization.” For fruit trees we speak of minimum “chill hours” each variety needs in order to bloom come spring. So the second question that comes to mind is “How did the tree erroneously bloom in October before it got any chill hours?” Well, rule no. 1 of plants overruled the vernalization rule. Cold or no cold, the tree chose to try to go to seed before it croaks.
The odds are the tree in question is going to survive as it has after dry spells in the past. But based on the picture I saw, it won’t have much of a bloom in the spring. The bloom buds were developed during the summer, just as they are for all early spring bloomers. Any buds that opened in the fall are history and will not produce blooms again.
Sometimes we see a tree or shrub with a few scattered fall blooms and don’t even notice any bloom shortage in the spring. But when a fall bloom crop is as full as the one on the Texas Bradford, there will be very few if any blooms next spring. Each summer-made bud can only make one bloom and when it’s gone it’s gone.
I know it is amateurish to say a plant “thinks.” I’m sure there is a proper understanding of plants reacting to stress that includes biochemistry and DNA and so forth. But I didn’t major in botany in school. I studied hogs and I guarantee you they think.
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Terry Rector writes for the Warren County Soil and Water Conservation District, 601-636-7679 ext. 3.