Getting Viburnums to bear Fruit

Last year I posted a blog on how using cloned plants may reduce the viability of seed produced in the garden. In some cases this is not a bad thing from a design point of view, if it is desirable to limit the number of ‘spontaneous’ seedlings and maintain a 'clean' ground plane. If your goal is to produce seeds and berries for wildlife, then the use of sterile, or self-sterile plants is of no advantage. The situation that brought this up was that the Viburnum nudum ‘Winterthur’ that I have has never produced more than a couple of small berries each year. After 5 years of this I investigated the situation and leaned that in order for Viburnums to produce seed it must be pollinated by a genetically distinct individual. (You see most cultivars are clones of the same individual.)  So last summer I picked up a straight species form of Viburnum nudum and planted it nearby.

These pale green berries will turn pink, then dark blue as they ripen.

This year I’ve got many, many more berries forming on the ‘Winterthur’, as well as the species plant. The species and ‘Winterthur’ bloomed at the same time; this is very important for cross-pollination. There is a difference in form and fall color between the two plants. ‘Winterthur’ is more upright and the fall colors on a single plant vary from light orange to red. The species plant is more lax and turn a rich burgundy color in the fall. Now I’m looking forward to seeing some of those brightly colored berries later in the fall.

Fall color for 'Winterthur' cultivar

Viburnum nudum species in early November.



Only a few of the signature blue berries
matured on this lone Arrowwood Viburnum.



Earlier this year I also added an Arrowwood Viburnum, Viburnum dentatum ‘Christom’= Blue Muffin®, to fill a gap in a shrub border. To my knowledge there are no other Arrowwoods in the neighborhood. This species of viburnum blooms 3-4 weeks earlier than the ‘Winterthur’ and only two clusters of late blooms overlapped with the opening of the flowers on the ‘Winterthur’. On inspection today, the Arrowwood has just a few mature berries on the plant, all of the other flowers just fell off shortly after blooming. So it may be that the pollen from these two species is compatible, but their blooming times are so different that they are not practical mates.

In any case, now when I recommend Viburnums in a wildlife-friendly garden, I try to include two different cultivars of the same species, or look to see if there are some other plants of the same species growing nearby. I will need to look for a chart with bloom times for all of the Viburnums to see if there any other possibilities for interspecies compatibility, as is done with Holly.

The Natives are Restless - What's happening as Summer approaches

As spring is drawing to a close, many of the summer blooming natives are getting ready to pop. This week I wanted to give an update on how the Native plants in my garden are doing.

I was very pleased to see that the Alleghany Vine, Adlumia fungosa, has begun to bloom with its little pale pink hearts. Last year it did not begin to bloom until mid-late June. This year I am letting it find its way in a more natural way, rather than forcing it to climb a trellis. In this way it is less likely to be twisted and broken off in the wind. IOt is a little difficult to see with its delicate frilly foliage and light colored flowers.  Now I just have to avoid stepping on it.

If these plants do well I will add in some new ones that I started from seed this year.  I hope that will get a stable population growing.

The little Rosy Sedge that I talked about a few weeks back is getting closer to bloom. This particular plant is so heavily shaded that the inflorescence, in fact, the whole plant is about half the size it gets in a more open location. I would never have spotted this development if I were not actively watching for it. I hope I can show you a good image when its flowers are actually open.

Correction: Two Stems of Meadowsweet

I have two native Spiraea growing here, Steeplebush and Meadowsweet, S. tomentosa and latifolia (or alba), respectively. While there can be easily distinguished by the different shapes of the flower spike, the leaves are also different. This is the first year that I could clearly detect the difference in the leaves. Steeplebush has a soft fuzzy leaf relative to the smooth leaf (glaborous) of Meadowsweet. In the photo you can also see that leaves of the Meadowsweet and more relaxed, but that is hard to tell if you don’t have a side-by-side comparison. While the habit of these two spiraeas is rather open, relative to the tightly mounded Japanese Spirea (S. japonica), I am surprised that these native species are not used more often in the residential landscape. In my garden Meadowsweet has proven to be a very versatile shrub, growing under a wide variety of conditions and blooming throughout the summer. It also can be pruned to tame it exuberant growth without compromising its ability to bloom.

The Red Columbine, Aquilegia canadensis, is still blooming away. Here it is shown with one of my Meadowsweet bushes just behind it.










Lastly, I planted two Winterthur Viburnums (V. nudum ‘Winterthur’) 4 years ago and they are both hitting stride now. (Their slow development was due at least in part to their proximity to the shade of a Norway Maple.) These buds will open to form corymbs of small white flowers. More interesting will be the pink and blue berries to follow.