By Tim Wood  

All rights reserved ©  Spring Meadow Nursery, Inc.

If I told you of a flowering shrub that is hardy to zone 2, is adaptable to poor soils, can withstand drought or bog conditions, is covered with masses of bright flowers from June until frost, and is easy to grow, would you be interested?  Of course you would.  These are the attributes that make an excellent landscape plant. What if I told you it came in yellow, white, orange, pink and red bloomed cultivars.  What if I told you the plant I just described was Potentilla fruticosa.  Did I surprise you?  It surprised me,  because even with all of these great attributes it has taken me some time to get excited about this plant.  My opinion of this plant has changed.  This is a great landscape plant!  

Why has my opinion of Potentilla changed? Well for several reasons.  First, I used to be a plant snob.  I used to look down on common plants.   Give me the rare, the obscure, unusual plant  thank you and then I can get excited!  Let me tell you about Pterostyrax corymbosus, Ampelopsis brevipidunculata or Kirengeshoma palmata and watch my excitement level rise.  Let me speak in obscure, hard to pronounce latin names and impress you with my depth of plant knowledge!  Yes, I confess I was a plant snob.  Actually I am a reformed plant snob.  According to my twelve step program PSA (plant snobs anonymous) I will always be a plant snob.   I must take one day at a time, and try to stay clean. 

Potentilla, depite being common, is still a great landscape plant.  Very few plants have the attributes it does.  You can plant it with the assurance that it will live.  It requires little, if no care once established.  It is compact and free flowering.  It is easy to site:  It can be used as a foundation plant, in the perennial border, in mass planting, as a low hedge and even as a specimen.  Potentilla does not need to be dead-headed, divided or cut back in the fall.  You don’t have to spray it weekly for blackspot like some other members of the rose family.  And to make the native nuts happy, Potentilla fruticosa is indigenous to most of the northern hemisphere, including Michigan.

The third reason I’m excited about Potentilla is that the plant is becoming more refined.   New and better cultivars are appearing.  It use to be growers only carried Jackmanii, and other larger cultivars which are great for commercial and large home landscapes.  Now we can find more diminutive forms, spreading forms, doubles and semi-doubles, and just about every color except the blues. Potentilla comes in enough flavors it can satisfy any ones appetite.

CULTURE

   Although Potentilla fruticosa is natively found in boggy areas it can also be found growing on higher, drier ground.  Once established the plant is quite tolerant of drought conditions, however when its massive root system is confined to a growing container it can easily wilt.  Wetting agents should help improve water penetration, but extra water will still be necessary during the heat of the summer.  A 2 ¼ “ liner can easily fill a two gallon in one season even with moderate fertility levels. 

   Shearing when young will help the plant build a nice body, but little pruning is needed until the plant is much older.   With time, plants in the landscape may require rejuvenation.  Removal of 1/3^rd of the old wood and light shearing should do the job.  The plant can take heavy pruning if necessary. 

   Although the plant has few serious insect and disease problems in the landscape, production growers should scout for aphids, spittlebug and two spotted spider mites and treat as necessary.  Rust can be a problem in production situations, especially with the orange cultivars.  To control rust avoid irrigation late in the day or at night.  Provide adequate spacing for air flow.  Rake and burn fallen leaves, clippings and debris when possible.  Preventive sprays are also available.  Once placed in the landscape, Potentilla should experience few, if any, insect or disease problems. It is relatively carefree.

 CULTIVARS

Last summer I had the opportunity to visit the University of Minnesota Landscape Arboretum. Believe it or not, one of the highlights of the Arboretum was the Potentilla collection.  Dozens of cultivars, planted side by side, in full bloom gave me the opportunity to choose my favorites.  With so many yellow cultivars to choose from I stood back and examined the forms and boldness of color to pick my favorites.  My eye went straight to Dakota Sunspot®.  Even though the plant was small and compact the color was the brightest golden-yellow of them all.  The leaves were a nice dark green which is unusual for Potentilla and made a nice background for the flowers.  Goldfinger was the next to catch my attention.  Its flowers are were bright and covered the tight, mounded plant.  Gold Star is a distinct selection out of Germany that has great potential. It's blooms the size of a half dollar and it has a nice tight habit.

Great anticipation and excitement surrounded the first introduction of the first red cultivar - Red Ace. The plant blooms red in England, but unfortunately, in the U.S. it blooms a poor orange yellow. Red Ace is also a weak growing plant. According to Dr. Campbell Davidson, who is the International Registration Authority for Potentilla, “All of the pink and red cultivars I’ve seen bleach out in the summer.  Most of these plants originated in the British Isles or Holland. They do fine in a cooler climate, but not as well in North America.  Heat and drought conditions will bleach out the color.”

Red Sunset is an erroneous name for the cultivar Sunset which is a nice yellow-orange flushed with streaks of red.  This beautiful  plant fades to shades of peach and yellow. 

White flowered Potentilla has become quite popular.  The two most popular white flowered cultivars are Mckay’s White and Abbotswood.  Abbotswood is smaller in stature and has larger, pure white flowers, while Mckay’s White has creamy white flowers.  It's  interesting to note that Abbotswood  the one of the earliest cultivars to bloom. Snowbird is a wonderful new white cultivar,  developed by the University of Manitoba, that has doubled, pure white flowers.

Pink seems to be the hot color in Potentilla and a lot of new pink selections are coming out. Pink Whisper, another University of Manitoba introduction, Royal Flush, Floppy Disc  and Pink Veuaty are all new pink selections.  Floppy Disc has the added attraction of having semi-double flowers. Unfortunately, just like the reds these pink blooms also fade. I am still evaluating these plants to determine which, if any, will not totally bleach out, or which ones hold their pink color longer.  I asked Campbell Davidson what his favorite pink Potentilla was he said, “Pink Beauty.   Not only is the flower nice, it has a nice compact habit as well.”

   Tangerine, Sunset, and Apricot Whisper are variations of orange.  Tangerine, which probably has the deepest orange color, seems to have the most problems with rust.  Sunset, true to its name changes hues starting out orange with red streaks and progressively changes to a pleasing yellow salmon. Apricot Whisper, true to its name offers a whisper of Apricot.

    To get the longest life out of the colored cultivars ample moisture and partial shade is recommended.  The colors may still fade in the heat of summer, but they should last longer.   If this fails to satisfy you then try to view the changing hues as an asset.  Sell the idea you get two or three colors for the price of one. Regardless of the colors you choose, there is enough cultivars of Potentilla to fit your landscape needs.

    No longer will I walk past a planting of Potentilla with my nose high in the air.  Yes, it is a commonly used plant, but its use is warranted.  And why do you suppose that certain plants gain the popularity of the masses?  They out perform other plants and they fill a need that other plants can not fill.  Yes, I can enjoy and respect the attributes of this plant even though everyone else can pronounce the scientific name.