Ask the master gardener: why isn’t my plant growing? – Brainerd Expedition

Dear Master Gardener: I bought a Mandevilla to mount my obelisk but it doesn’t. A friend bought a Dipladenia and they look alike. Is it the same plant with different names? Why is my plant not vine?

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 like a shrub. The flowers and leaves of Dipladenia are smaller than Mandevilla, more pointed and slightly shiny.

Mandevilla is a vine and needs a structure to climb. The shrub-like Dipladenia is ideal as a filler plant in a container. When you go to the garden center, be sure to choose the right plant because one can be labeled as the other. Since the plant you purchased to climb your obelisk is non-climbing and remains shrub-like, you likely got a Dipladenia rather than the intended Mandevilla.

The shrubby Dipladenia is ideal as a filler plant in a container.

Contributed / Jennifer Knutson

Dear Master Gardener: Cutworms are decimating transplants and seedlings in my vegetable garden. Can I do something?

Answer: There are different species of cutworms, but they are all similar in general appearance. They are smooth with very few hairs and measure about two inches when fully grown. Cutworms vary in color between brown, tan, pink, green, gray or black. They usually curl into a tight C-shape when disturbed.

Common vegetables they attack are asparagus, beans, cabbage, carrots, celery, corn, lettuce, peas, peppers, potatoes, and tomatoes. Cutworms feed in the evening or at night and hide in plant debris during the day. New grafts, young plants and seedlings are the most susceptible to cutworm damage because their stems are softer.

Cutworms wrap their bodies around the stem and feed on it, causing the plant to cut just above the soil surface. Cutworm numbers can vary from year to year and when their numbers are high they can cause serious damage to a garden.

The use of pesticides in the vegetable garden is not necessary. When you see them in your garden, pick them up and drop them in a container of soapy water or crush them. Remove all 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 out of stiff paper, cardboard, aluminum foil or a tin can and place it around the stem of the plant. Push the collars into the ground about an inch or 2 inches. This will create a physical barrier to prevent cutworm larvae from feeding on the plants.

Dear Master Gardener: I’ve seen Annabelle hydrangea flowers used as wedding cake toppers. Is it just a decoration or is it edible? Which 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 decoration, which might make you think they are edible, but they are not! Hydrangea flowers contain low levels of cyanide.

It is important to only choose flowers that are safe to eat and have not been treated with pesticides. Part of a plant is safe to eat, but don’t assume all parts are safe – it’s usually the petals of the flower that are edible. The flowers of herbs usually taste the same as the leaves.

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

  • Strawberry from the Alps (the flowers taste like strawberries, the leaves are used for tea),
  • Anise hyssop (flowers and leaves have licorice flavor, used in tea),
  • Apple or plum (flowers are sweet with a sweet floral flavor, use candied or as a garnish),
  • Single buds (flowers have a delicate spicy-sweet flavor, eaten fresh or dried for tea),
  • Calendula (petals are a slightly bitter substitute for saffron, 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 slight cranberry-citrus flavor, used in teas),
  • Nasturtium (flowers and leaves have a peppery taste, use them fresh in salads for a spicy flavor),
  • Pansy (the flowers have a green, herbaceous flavor),
  • Roses (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 the white base of the petal; use rose hips for tea and dressing),
  • Scented geranium (the flavors of the flowers vary according to the varieties; flowers and leaves perfume jellies, sugar, butter, cakes, tea, honey),
  • Tuberous begonia (the flower petals have a tart citrus flavor),
  • Tulip (the flower petals have a pea or bean flavor, remove them from the stem and use them in salads).

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

Answer: Yes! Blue Beech (Carpinus caroliniana), also known as American Hornbeam, is a wonderful small ornamental tree native to Minnesota. It is one of the few landscape trees that grows well in full shade. Blue Beech can be grown as a tall shrub, a single-stemmed tree, or a multi-stemmed tree. It offers multi-season interest.

The pendulous, pagoda-shaped seed heads are bright green and contrast nicely with the summer foliage; then they ripen to brown and cling to the tree over winter. The smooth, bluish-gray ornamental trunks are an eye-catcher in the winter landscape.

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

You can get your garden questions answered by calling the new Master Gardener Helpline at 218-824-1068 and leaving a message. A master gardener will call you back. Or, email me at and I’ll reply in the column if space permits.

The University of Minnesota Extension Master Gardeners are trained and certified volunteers for the University of Minnesota Extension. The information provided in this column is based on academic research.

Comments are closed.