Dear Master Gardener: I spent hours playing with hollyhock blossom “dolls” when I was a child but don’t see them much anymore. Are they difficult to grow because I’d love to have some in my garden?
Answer: Hollyhocks (Alcea) are still a favorite with children and are not difficult to grow. They provide color (red, yellow, pink, purple, and white), add height to garden beds, and screen unsightly structures, such as garbage cans. Some will remember that old outhouses were often surrounded by cheerful hollyhocks. There are over 60 varieties of this short-lived biennial, some of which have been known to grow up to 14 feet tall. One problem with them comes from not knowing what biennial means. A biennial plant has a two-year growth cycle. In the first year the seed germinates and forms a rosette of leaves but does not bloom. The second year it sends up a stalk, blooms and produces seeds. Hollyhocks purchased at a nursery are usually second-year plants, so they will bloom in the year purchased and will produce abundant seeds, which will germinate the next summer but will not bloom that year. Sometimes a few hollyhocks may rebloom a second year so that after a few years a patch will have blossoms every year. The button-like seed pods are attractive and interesting, too, and are also of interest to children, who like to pop or explode their abundant seeds. The blossoms appeal to hummingbirds and butterflies and make good cut flowers. Hollyhocks, like all plants, have some disease and insect problems. The main one is rust, which may be unsightly but is rarely fatal. Good air circulation, watering from below the leaves to keep them dry, and removing and destroying diseased leaves usually keep the problems under control. Full sun and regular moisture will help keep hollyhocks happy, too.
Dear Master Gardener: We have a small shaded lot and clay soil. We planted five Rhododendrons as foundation shrubs in the front and they died. Then we planted Microbiota and got the same result. Then boxwood — same result. Last year we planted Hetz Midget Arborvitae and I don’t think they are going to make it either. After years of failure, what do you suggest?
Answer: I was walking around a neighborhood last summer and a woman was in her yard, so I complimented her on her perfect boxwood shrubs along her foundation. She informed me that she ordered them online and they were plastic. In my defense, I had sunglasses on and the shrubs were at a distance. When all else fails there is always plastic!
First, I suggest you get a soil test to see if there is an issue with your soil in that area. You can get information and instructions on getting a soil test through the University of Minnesota at the following website: https://soiltest.cfans.umn.edu . The lab will evaluate soil fertility, pH level, and/or problems due to excessive salts or fertilizer materials and send the appropriate fertilizer recommendation for good plant growth. Gardeners can request and pay for additional information, which is described at the website.
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Next, I’ll address clay soil, which can be difficult to work with. Dry clay tends to be hard and when it gets wet it’s sticky and hard to manage. According to Oregon State Extension, “Bark, manure, leaf mold, and compost are among the organic amendments commonly used to improve clay soil. Applied to the soil surface, these materials form a protective blanket that slows evaporation and reduces soil hardening.” Oregon State recommends applying 2-3 inches of organic materials to garden beds without mixing them in.
Once you find out if there is an issue with your soil and if any amendments are recommended, the next step is to choose the right plant for the conditions you have. All of the shrubs you mentioned are great choices for shade. Rhododendrons can be tricky because they need a soil pH of 4.5-5.5 to survive or thrive. Boxwoods are hardy to zone 4 and prefer neutral to slightly alkaline soil that drains freely. Microbiota is one of my favorite low-growing evergreens, but it needs very well-drained soil. In poorly drained soil it often gets root rot and dies. Arborvitaes perform well in a wide range of soils as long as it’s well-drained. Unfortunately rabbits like to nibble on them and deer devour them.
A deciduous shrub that is native to Minnesota, hardy to zone 3, and can handle just about any landscape challenge you can give it, is Aronia (black chokeberry). The berries are edible, but quite astringent. Autumn Magic reaches 5 feet in height by 4 feet in width at maturity and Iroquois Beauty gets 4 feet by 4 feet at maturity. Diervilla (bush honeysuckle) is another tough, hardy, native shrub that may be an option. It gets 3 feet by 4 feet. Both these shrubs sucker, so as a foundation plant you will want to keep on top of pruning out suckers.
Dear Master Gardener: When my Phalaenopsis orchid is done blooming, how do I cut it back? Will it rebloom?
Answer: It depends. Of the commonly available orchids, the Phalaenopsis (moth orchid) is the only one that may rebloom from its old spike. Young or weak plants may not rebloom and some are not genetically capable of reblooming from the old stem. If it is a small Phalaenopsis, cut the stem to the base where it comes out of the leaves. If it is a larger one, you can leave the stem on and it may continue flowering, but the flowers are usually smaller. Sometimes people cut off the stem at the base and it blooms again in several months. Another option is to cut off the stem in between two nodes (the brown lines on the stem below where the flowers were) which will initiate flower production. It is very important to use a new straight-edge razor blade or sterilized pruner to avoid spreading a virus to your plant.
Dear Master Gardener: I love the color blue. I have purchased plants that say they have blue flowers but when they bloom, they are purple. Are there any true-blue flowers?
Answer: Color is often considered when deciding whether to grow a flowering plant. Blue is popular and represents peace and serenity. What passes for blue in the nursery trade is often violet or purple with blue undertones. Some sources say naturally occurring blue flowers do not exist and others say it is a very rare phenomenon. In my experience, there are a few flowers that come very close to being “true blue.” Bachelor Button (Centaurea cyanus) Blue Boy is an annual that is sky blue and a great addition to the cutting garden. Morning Glory (Ipomoea) Heavenly Blue is a blue flowering annual vine. Two perennial Delphinium cultivars that appear blue are Pacific Giant Bluebird and Blue Buccaneers. Grape Hyacinth (Muscari) Blue Magic has sky blue flowers with white tips and is fragrant. The hydrangea that can turn blue in acidic soil is not reliably hardy in zone 3.
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You may get your garden questions answered by calling the new Master Gardener Help Line at 218-824-1068 and leaving a message. A Master Gardener will return your call. Or, emailing me at umnmastergardener@gmail.com and I will answer you in the column if space allows.
University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. Information given in this column is based on university research.
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