Questions on: Potentilla

Ron Smith, Horticulturist, NDSU Extension Service

Q: We have 11 potentilla plants in one section of our landscape. I think the plants are too close to each other because they are growing together to form a triangular hedge. My wife wants me to remove about four of them and space the others. Is this possible without killing them? (e-mail reference)

A: Wait until they go dormant after a couple of good killing frosts. You can do it this fall or early next spring before the buds break.

Q: When is the best time of the year to plant new potentilla bushes? (Fargo, N.D.)

A: Anytime you have a plant handy, the ground isn't frozen and you have water available to get it established. In other words, now would work for a container plant and so would later in the fall or next spring.

Q: My husband bought two potentilla (goldfinger) shrubs at a local nursery during the first week of June. I planted them a few days later. I was concerned with all the hot weather we had, so I began to water them every other day by placing a small trickle at the base of the plant for a short time. They never flowered and recently have turned brown, but still seem to have life in the stems. I fertilized after a few weeks, thinking they would come back, but they never looked better. What am I doing wrong? I feel like I am doing too much or not enough of something. How do I know if they are dead? It is so hard to tell. (e-mail reference)

A: Potentillas are “xeric” plants that need very little water to survive and thrive. Your watering likely has caused the problems you describe. Scrape the bark tissue on a couple of stems. If the tissue beneath is still green, that means there is life! If it is not green, then the plant is dead and you are better off disposing of it and replanting.

Q: I bought four small pontentilla bushes that bloom reddish pink flowers. What other plants or bushes complement pontentilla and are low maintenance? (e-mail reference)

A: Why not visit a local garden center and see what lights your fire? I don’t know where you live, the kind of light exposure you have, the soil type or what objectives you want to achieve in your landscaping, other than low maintenance. A local garden center that employs a designer can help you better than I can. You need to have a plan developed to have a cohesive, functional and attractive looking landscape.

Q: I planted potentilla, spiraea and a dogwood 18 inches from the basement wall of our house. I am concerned that the roots from these shrubs might find their way into the weeping tile around the footing of our basement. I would estimate that the tile is at a depth of about 5.5 feet. (e-mail reference)

A: I have dug every kind of shrub, including the ones you mention, out from the foundations of old houses and never have found any roots that go down 5 feet. I think you are safe.

Q: We have three jackman potentilla bushes that are about 20 years old and are not blooming much anymore. Could we cut them back to probably a foot tall and start over again? We also have a dropmore scarlet honeysuckle vine that blooms very nicely but is getting woody and needs some severe pruning. (e-mail reference)

A: Cut them back to the ground in early spring before new foliage shows. Do the same with your dropmore honeysuckle.

Q: I have a potentella that looks terrible. Its mate died last year. Should I be pruning this bush in the fall or spring? There is no shape to it at all. It just grows all over the place and has a lot of exposed brown branches. (Fargo, N.D.)

A: They tend to get that way with age. You should mow it down early next spring before it leafs-out. The flush of new growth that follows can be easily shaped.

Q: What variety of potentilla should I plant? (Bismarck, N.D.)

A: There are over 100 cultivars of potentilla fruticosa. They range from Annette to yellowbird. Visit local garden centers to see what is available and popular. They come in yellow, red and white flower colors. The choice is yours!

Q: I have three potentilla plants that I bought from a catalog. They look beautiful every year but after four years they have never bloomed. They are planted in a sunny location and have good soil and drainage. It gets regular watering and feeding. Can you tell me what I'm doing wrong? (E-mail reference)

A: You are being too good to them. Allow them to suffer a little, or initiate traumatic stimulation by driving a straight edged spade into the soil about a foot or so from the base of the plant in two or three spots. You should get flowering next year or the year after at the latest. After four years they can pretty much fend for themselves. Water only during extended drought (three or more weeks without rain) and forget fertilizer.

Q: Would you please tell me if I can round out a potentilla bush? Mine is really unruly and I would like to round it. Someone told me it would not bloom if I did that. (E-mail reference)

A: Most blooming deciduous shrubs should never be rounded out. Selective pruning should be followed by removal of the oldest canes right back to the soil line each year. This keeps the plant in an attractive informal form and provides continuous blooming along with fresh new growth. The rounding out will leave a bunch of sticks with a witch's broom type of growth, something completely unnatural.

Q: I have a potentilla bush that is about six or seven years old and is dying from the bottom up through the middle. Would it come back if I cut it back? Should I cut it in the spring or fall? (Selby, S.D.)

A: Prune it back to the ground in the spring, before new growth begins. You should see a mass of new, healthy growth.

Q: I bought some Potentilla bushes because the tags said they could survive in sun or part shade. They are all dying. I think it is because it is too shady where they were planted. Are there some flowering bushes that I could plant in a shady spot? It would maybe get a few hours of sunlight because there are large maple trees all around our house. (E-mail reference)

A: The Annabelle hydrangea flowers nicely in the shade.

Q: About 10 years ago we planted four Potentilla bushes in the front of our house (south side). They bloomed beautifully for many years. In the last year or two they have been flowering less and less, and now three of them are completely dead and the last one has only a few blossoms on it. Over the years the cats would use them as scratching posts and weeds have grown around them quite a bit. Could we have done something to save them? (E-mail reference)

A: Regular pruning and weeding would have been a big help. If they are not completely dead, then perhaps it is not too late. Early next spring while they are still dormant, cut them back completely to the ground and put 1/2 cup of fertilizer around each one. If there is any life left, you will get a mass of new, fresh growth that may or may not bloom that same year. If not, it will almost for certain do so the following year, assuming that they are not now growing in shade.

Q: At what time of the year does one trim global arborvitae? Should Potentilla be cut back and when? Does one cut back Clematis in the fall, spring or not at all? (Grenville, S.D.)

A: The best time to trim your arborvitae is in the spring when active growth can take place. Cut the potentilla back in early spring prior to leaf-out. Most clematis varieties bloom on new growth produced in the spring. Cut back in early spring to about 6 inches of old growth remaining.

Q: Can I prune my pink potentilla bush round? If so, when is the best time to do that? Also, when should I separate my daylilies? (Ayr, N.D.)

A: Best time to prune potentillas is early spring before they leaf out. I don't recommend pruning them to a "round" form. Simply cut out the oldest canes at the base of the plant. A natural shape, which the plant will try to maintain anyway, is more attractive and healthier for the plant.

Daylilies can be separated either this fall or early next spring. Plant them at the same depth they were originally.

Q: Do you have any advice for people growing potentilla for the first time? (Box Elder, S.D.)

A: Plant them in full sun, water every two weeks if there is no rain and fertilize only when needed--which is likely never in average soils. Cut out oldest growth early in spring before leaf-out.

Q: I have a snowball bush that was cut off by mistake, and now the blooms on it seem really small. Will it get big blooms on it again? Also, is there more than one kind of potentilla? I saw one with really large flowers and would like to know what kind it was. I have one that blooms a lot smaller, but I like the larger flowers. (Walcott, N.D.)

A: Don't worry, your snowball bush will be just fine—just don't cut it back so late next spring!

There are many Potentilla cultivars on the market. Yellow, white, red, big blooms, small, etc. I count some 56 selections in my reference books. What you saw was likely the Jackman's variety. It has yellow flowers ¼ inch to 1½ inches in diameter. Yours could be the Gold Drop form—a little smaller.

Q. This bush is getting browner by the day. I don't know what it has or what to do. Should I cut it down or leave it?

These flowers came up by my mailbox. I would like to know what they are and if they will come up next year.

I read your column all the time and really enjoy it. Thanks. (Glenfield, N.D.)

A. Give your potentilla a good, hard cut-back to ground level this fall and see what happens next spring. Many times they recover nicely. At least you are giving it a chance. It will not flower next year if it survives, but should in subsequent years.

I was unable to identify your sample due to specimen damage. Judging from the seed produced, you should see them again next year.

Q: I have a potentilla bush which is looking pretty stressed. Can I prune it back to about 6 inches or would it be better to wait til spring ? (E-mail reference, Jamestown, N.D.)

A: Better to wait until spring. You'll get a good flush of growth then.

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