Ask the Master Gardener: Why isn't my plant vining?

This week, the master gardener column looks at picking the right plant, protecting against damage from cutworms by using stiff paper or aluminum foil, provides a list of edible flowers and notes an ornamental tree that can be a spectacular addition with benefits year-round.

A Mandevilla flower.
Mandevilla is a vine and needs a structure for climbing.
Contributed / Jennifer Knutson

Dear Master Gardener: I purchased a Mandevilla to go up my obelisk but it isn’t vining. A friend purchased a Dipladenia and they look alike. Are they the same plant with different names? Why isn’t my plant vining?

Answer: Mandevilla and Dipladenia look very similar and are sometimes sold as the same thing, but they have different growth habits. Mandevilla is a vine and Dipladenia is more shrub-like. The flowers and leaves of Dipladenia are smaller than Mandevilla, more pointed, and slightly glossy.

Mandevilla is a vine and needs a structure for climbing. Shrub-like Dipladenia is great as a filler plant in a container. When you go to the garden center, be careful that you are choosing the right plant as one can be labeled as the other. Since the plant you purchased to climb up your obelisk isn’t vining and is staying shrub-like, you probably got a Dipladenia rather than the intended Mandevilla.

The shrub-like Dipladenia is great as a filler plant in a container.
Contributed / Jennifer Knutson

Dear Master Gardener: Cutworms are decimating my vegetable garden transplants and seedlings. Is there something I can do?

Answer: There are different cutworm species, but they are all similar in general appearance. They are smooth with very few hairs and are about two inches at maturity. Cutworms range in color from brown, tan, pink, green, gray, or black. They usually curl into a tight C-shape when disturbed.


The common vegetables they attack are asparagus, beans, cabbage, carrots, celery, corn, lettuce, peas, peppers, potatoes, and tomatoes. Cutworms feed in the evening or night and hide in plant debris during the day. New transplants, young plants, and seedlings are the most susceptible to cutworm injury because their stems are more tender.

Cutworms curl their bodies around the stem and feed on it, causing the plant to be cut off just above the soil surface. The number of cutworms can vary from year to year and when their numbers are high, they can cause severe damage to a garden.

Begin picking rhubarb stalks as soon as they have reached their full length. Each variety is different and can vary from about 1 to 2 feet in length. Hold the stalk firmly, pull and twist. Immediately after harvesting, use a knife to cut off the leaves from the stalk.

Using pesticides in the home garden is not necessary. When you see them in your garden, remove them and drop them into a container of soapy water or crush them. Remove any plant debris from your garden to reduce egg-laying sites. Remove weeds, which can also serve as a host for young cutworm larvae.

You can also make a collar of stiff paper, cardboard, aluminum foil, or a tin can and place it around the stem of the plant. Push collars into the soil about an inch or 2 inches. This will create a physical barrier to prevent cutworm larvae from feeding on plants.

Dear Master Gardener: I’ve seen Annabelle hydrangea flowers used as a wedding cake topper. Is it just a decoration or is it edible? What flowers are edible?

Answer: Edible flowers are often used as a garnish. However, not all flowers are edible. Hydrangea flowers are sometimes used as a cake topper, which might make people believe they are edible, but they are not! Hydrangea flowers contain low levels of cyanide.

Moon gardens are intended to be a peaceful spot to rest, relax and appreciate celestial beauty.

It is important to choose only flowers that are safe to eat and have not been treated with pesticides. One part of a plant may be safe to eat, but don’t assume that all parts are safe – usually it’s the petals of the flower that are edible. Flowers from herbs usually taste similar to the leaves.

Here is a U of M list of some edible flowers:


  • Alpine strawberry (flowers have a strawberry flavor, leaves used for tea),
  • Anise hyssop (flowers and leaves have a licorice flavor, used in tea),
  • Apple or plum (flowers are mild with sweet floral flavor, use candied or as a garnish),
  • Bachelor buttons (flowers have a delicate spicy-sweet flavor, eat fresh or dried for tea),
  • Calendula (petals are a slightly bitter saffron substitute, more for color than flavor),
  • Daylily (flower bud flavor compares to green beans and eggplant, but open flower flavor is milder, flavor varies by cultivar),
  • Hibiscus (tropical) (flowers have a mild cranberry-citrus flavor, used in teas),
  • Nasturtium (flowers and leaves have a peppery taste, use fresh in salads for spicy flavor),
  • Pansy (flowers have a grassy, green flavor),
  • Pinks (Dianthus) (flowers have a sweet clove flavor, remove the base of the petal – usually white in color – it’s usually bitter; use in sorbets, cold drinks, salads with fruit),
  • Rose (use petals but remove white base of petal; use rose hips for tea and vinaigrette),
  • Scented geranium (flower flavors vary by variety; flowers and leaves used to flavor jellies, sugar, butter, cakes, tea, honey),
  • Tuberous begonia (flower petals have a tangy citrus flavor),
  • Tulip (flower petals have a pea or bean flavor, remove from stem and use in salads).
While red is by far a hummingbird's favorite color, they will also feed on blue, yellow, and purple flowers.

Dear Master Gardener: Does an American hornbeam grow in Minnesota?

Answer: Yes! Blue beech (Carpinus caroliniana), also known as American hornbeam, is a marvelous small ornamental tree that is native to Minnesota. It is one of the few landscape trees that does well in full shade. Blue beech can be grown as either a large shrub, single-stemmed tree, or multi-stemmed tree. It provides multi-season interest.

The pendent, pagoda-like seed heads are light green and contrast nicely with summertime foliage; then they mature to brown and hang on the tree through winter. The smooth, bluish gray ornamental trunks are eye-catching in the winter landscape.

Fall color is spectacular with shades from yellow and orange to scarlet – often all on the same tree. The seeds are a food source for songbirds.

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 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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