The Powerful Potentilla

By Melanie Mathieson
Gardening Guru

“Potentilla” means powerful in Latin. In the case of the shrubby cinquefoil, powerful refers to the strong medicinal qualities of the shrub. I like to promote the planting of native species in your garden, in order to improve your results as a gardener. If a native species survives quite well in the area, then a hybridized version of that plant will usually thrive in the region as well. The Potentilla or Shrubby Cinquefoil (Shrubby Potentilla) is one of the shrub species that is native to this region and to the north of us in the boreal forest. The native shrub is found in a bog habitat in extremely moist conditions. Because it thrives in a bog habitat it is usually found in the open and continuously exposed to the direct sun and nature’s harsh winter elements. The Potentilla found growing in the wild has yellow flowers. Usually growing to a maximum height of three feet and up to 2 feet wide it can be seen from quite a distance as the tallest plant in the bog. Fortunately gardeners can purchase a hybridized Potentilla species at the nursery that doesn’t need a bog habitat in order to survive in the urban setting.
There are over a 130 hybridized species of Potentilla, many of which are not hardy to our Zone 4 climate, but many varieties are. My recommendation when purchasing any tree, shrub or perennial is to always read the hang-tag carefully just to make sure that the one you have selected is hardy in our area. The hybridized species commonly found in our region have yellow flowers like the native species but are also available in orange, white or pink flowers and new in the last few years, a deep red flower. The foliage of these varieties is finely textured and is dark green on the topside of the leaf with silvery green on the underside. Again like the wild species the hybridized varieties are erect shrubs usually growing slightly larger than the wild variety. The hybridized variety will grow about 3.5 feet tall and 3 feet in width with their saucer-shaped flowers averaging at least an inch in diameter, and some of the newer hybrids even producing double flowers. This is a showy shrub that will bloom for most of the summer. The most popular varieties in our region are ‘Goldstar’, ‘Orange Whisper’, ‘Pink Beauty’, ‘Abbotswood’ and ‘Yellowbird’.
Many of the gardening books claim that the Potentilla is drought tolerant, but many of these books recommend that for best growth and flower display to make sure that the plant is well watered and planted in partial shade. Knowing that the native species grows in a bog habitat I tend to disagree with the claim that the hybridized variety is drought tolerant. Based on years of observations while assessing complaints from gardeners that are having trouble with their Potentilla showing extreme winter kill or generally bad growth and development, have them planted in very dry conditions. So I recommend good moist soil for planting your Potentilla. Make sure that you water the shrub well during the hot and dry spells in the summer months and continue right into the fall to ensure good winter survival. The best location for your Potentilla is in an area of the yard or garden that is shaded from the afternoon sun. This will ensure that the flowers retain their colour better, as well as, improve the long-term survival of the shrub. The shrub will tolerate full sun but be forewarned that the flowers will quickly fade and drop off.
The Potentilla may be a powerful shrub from a medicinal point of view but it is a short-lived shrub, usually only surviving up to ten years. They usually do not require any winter protection but they do require an annual spring pruning. Many gardeners are confused by the pruning process for these shrubs, but it is actually pretty easy once you know what and where to trim. Get ready to prune each spring as the leaves start to emerge. First trim all of the dead flowers from last year off the shrub where the stem of the flower meets the branch. After you have removed all of the old flowers check for any dead branches remaining on the shrub. When pruning the dead wood back, always prune to a branch intersection in the live wood. If you cannot locate an intersection you may safely cut the branch right back to the ground. Also at this time cut back any weakly growing shoots back to the ground. Finally a reshaping if needed, can be achieved by pruning the strong branches by up to one-third. Never severely prune these shrubs right back to the ground as they may not recover. I know many gardeners have been given this advice in the past and will most likely cause the shrub to die. The Potentilla shrub blooms on new wood so this annual spring pruning shouldn’t affect the current year’s show of flowers. The Potentilla is from the same plant family as the rose, hence the same method of pruning to ensure vigor and if you look closely the flowers do resemble small single roses. As I mentioned the Potentilla is a short-lived shrub so after about ten years you may start to see a rapid decline after each winter so you may want to replace that shrub with a new one.
The Potentilla is a very functional shrub. It can be planted in a perennial bed and look right at home. It can be a focal point in the yard and can even be planted in a container that is large enough to accommodate the roots and prevent them from drying out and freezing over the winter. The Potentilla also can be used to make a hedge or border planting and makes a great windscreen or backdrop for a perennial bed. It also makes a great planting to camouflage an unsightly area in your yard such as a composter, electrical box, air conditioner, etc.. Keep in mind that these shrubs can be easily damaged in the winter by snow shoveled from the driveway or street,being piled on top of them throughout the winter. Again these shrubs are very susceptible to damage and possible death if exposed to driveway, sidewalk or road salt. Keep this in mind when deciding where you would like to position the shrub in your yard or garden.
With these helpful tips and pruning instructions I know that you will soon be enjoying the ‘power’ of the Potentilla.