Friday, July 20, 2007

Peonies, Crocus, and Corylus: A work in progress

(image of an unknown peony cultivar (Paeonia sp.) I took at Tower Hill Botanic Garden, 2006)

I have recently received a number of excellent questions. I am calling this a "work in progress" because I am still researching and trying to find answers, but I wanted to share with you what I have found to date.

1 - I have 2 peonies - one of which I divided from the original. In the spring they show lots of buds with ants crawling happily all over them but only 4 or 5 of the buds actually flower. They're about 7 years old, in full sun, I fertilize them w/ bone meal in spring & fall, I prune them back to about 5 inches each autumn. What am I doing wrong?
2 - I started with about half a dozen bulbs for autumn flowering crocus (sativus). The bulbs proliferate - I have dozens now - & they put up plenty of foliage but only 2 or 3 bloom.
3 - I have a new Harry Lauder Walking Stick that I planted in April. It's growing much faster than I anticipated - from a foot, it's more than doubled in size. Is it o.k. to prune it &, if so, when is the best time to do it?


Regarding the peonies (Paeonia spp.) not blooming:
There is an old wives tale that peonies do not bloom for seven years if you transplant them. It is true that the roots hate to be disturbed, but as long as the crown buds were planted 2-3 inches below the soil level they should bloom the following year. This fall when you do cleanup perhaps you will want to excavate a little and see where the new buds are situated to make sure they are not too high or too deep. If the buds set and then we are hit with a late cold spell some of the buds can get blasted and never flower, but if this is happening year after year it seems safe to rule that out as a possible cause. Your cleanup practices seem appropriate; when I see them begin to die back I cut them flush to the ground and rake the area clean. Even though bone meal is recommended, I wonder if applying it in the fall and spring is a bit much. Because it is slow release, I would apply in the fall, but in the spring maybe you can just stick to just using compost. Peonies tolerate a wide pH range in the soil (6.0 – 7.0) and I have even seen them happy in slightly more acidic soil, so I wonder if the bone meal has slowly made the soil too alkaline (a pH of greater than 7). Have you ever had your soil tested? You can see why I want to research this question more.

Regarding the non-flowering Crocus sativus:
Fall-blooming Crocus love full, baking sun so if shade has slowly crept in the area that might help to explain the lack of flower. Taylor’s Guides state that Crocus sativus can lack flower if the summer is too cool and wet. I had thought Crocus preferred an evenly moist summer, but perhaps this species prefers a dryer summer. Of course, well-drained soil is a must, and added compost never hurts. You have mentioned that the bulbs are doing well, but have you divided them? For this species of Crocus, you want to lift and divide the corms every 3-4 years as the foliage begins to fade and die back naturally. Plant the divided corms about 3-4” deep, safely below the frost line, but do not plant them as deep as the 6” some may recommend.

Regarding the Harry Lauders Walkingstick (Corylus avellana ‘Contorta’):
I would take all the new growth as a good sign that the tree is establishing plenty of new roots as well. As you may have experienced when planting, these small trees have a very large root system given the relative size of the tree itself. I used to study under an arborist I admire greatly and he never recommended pruning newly planted trees until two or three years in their new location. The fundamental thinking is that pruning causes the tree to work harder to callus those cuts, and while getting established you want to stress the tree as little as possible. That being said, if you feel you need to prune it at this time, I recommend pruning this tree in late winter or early spring. Prune only what you have to maintain shape or remove dead, diseased, or damaged wood. Remember that your tree uses the majority of its stored energy for the process of leafing out in the spring, so again we want there to be as little added stress as possible. In the long run you should know that Corylus avellana ‘Contorta’ will reach 10’ or more in height and width at maturity. Over time the tree’s new growth will slow down, but you can expect it to grow at a moderate rate for the next few years.

1 comment:

  1. I transplanted peonies a year ago. They came back this year but did not bloom. I was advised by a local garden center that I should have given them bone meal in the fall after I planted them. Should I give them bone meal this fall (it is now October and I live in Massachusetts) or wait and fertilize them in the spring?