Master Gardener: Add spectacular color to gardens

Phlox subulata are great additions to rock gardens, another plant is underused as a fabulous addition to a sunny garden, how to keep rhubarb healthy and productive and do marigolds really repel rabbits and bugs -- are all part of this week's Master Gardener column.

Moss phlox has a creeping habit that creates a carpet of flowers that blooms in late May and early June. Photo by Jennifer Knutson

Dear Master Gardener: This week I saw some brilliant, dark pink, low-growing flowers growing in a boulder wall. They’re gorgeous – what are they?

Answer: It sounds like Phlox subulata, also known as creeping phlox or moss phlox, which are in bloom right now and looking quite spectacular! Phlox subulata are native to parts of Minnesota. They are great additions to rock gardens and will drape slightly over a rock or retaining wall and are excellent ground covers for sunny areas. Moss phlox has a creeping habit that creates a carpet of flowers that blooms in late May and early June. Cultivars come in pink, white, lavender, and magenta. This plant is typically not preferred by deer.

Dear Master Gardener: A friend said he is putting in a baptisia. What type of plant is that?

Answer: Baptisia australis, also known as blue false indigo, is an underused perennial that makes a fabulous addition to the sunny garden. It is a long-lived perennial that has a shrub-like appearance and reaches 3 to 4 feet in height and width at maturity. Choose its final resting place because it has a long tap root and does not transplant well. The soft bluish-green foliage looks lovely all season long. It is in the pea family and has long, lupine-like spires of pealike flowers that bloom in June. The flowers last about two to three weeks. Various shades of blue and purple are the most common colors, but you will also find new cultivars that come in yellow, white, and cream. Cherries Jubilee is a maroon and yellow cultivar for those University of Minnesota fans! After those beautiful flowers have faded away, they are replaced by interesting green, oblong seed pods that grow 2 to 3 inches long, then turn charcoal black in late summer or early fall. They have considerable ornamental interest! The mature seedpods contain seeds which rattle around when shaken. In fact, children once used them as rattles. Baptisia australis is deer and rabbit resistant, hardy to zone 3, attracts butterflies, has multi-season interest – your friend is adding a great plant to his garden!

Dear Master Gardener: My rhubarb plant has sent up a large white flower. What should I do about it?


Answer: Flower production is a natural part of rhubarb’s reproduction cycle and is called “bolting.” It leads to the production of seed, which you don’t want because the seed-produced plant is inferior to the parent plant. Also, plant vigor and next year’s crop will be reduced if the flower is left to mature and set seed. So, remove the flower as soon as it appears, which may happen more than once, especially early in the season. The flower takes energy from the plant, resulting in fewer and inferior stalks. Some varieties of rhubarb are more prone to bolting than others, as are older plants. There are several things you can do to keep your rhubarb in top shape: fertilize each spring with a 10-10-10 fertilizer, divide your patch every five years and stop harvesting the stalks by July 4.

Dear Master Gardener: Are marigolds edible and do they really act as a natural pesticide?

Answer: Marigolds, a native of Mexico, have been grown in gardens throughout the world for hundreds of years and are one of the most popular bedding plants in the United States. On a cultural note -- families in Mexico plant marigold seeds and think of their loved ones as they watch the flowers grow then blossom. The brilliant orange flowers are believed to help guide the souls of loved ones home. They celebrate Dia de los Muertos (Day of the Dead) with family and friends (which falls Nov. 1-2 this year) and pray and remember loved ones who have died. The meaning of marigold is grief.

Calendula officinalis (pot marigold), Tagetes erecta (African marigold) and Tagetes tenuifolia (signet marigold) are edible. Pot marigolds have been reported to taste “tangy and peppery,” African marigolds “strong and pungent,” and signet marigolds “citrus-like or spicy tarragon flavor.” It is important to correctly identify flowers before consuming them and to make sure they have not been treated with pesticides. The only way to ensure flowers have not been previously treated with pesticides is to grow them from seed or buy organically grown plants.

Although there is little documentation and research to back it up, some garden experts agree that French and African marigolds repel some insects and nematodes and they “must smell to repel.” Some people also believe that French marigolds repel mosquitoes.

According to Iowa State University Extension, not only do marigolds not repel rabbits, deer or other animals, rabbits occasionally browse heavily on marigolds. Research studies there have also concluded marigolds are not effective in reducing insect damage on vegetable crops.

Dear Master Gardener: My chives are flowering. Are they edible like the leaves?

Answer: Yes, the pretty, purple flowers are edible and have a slight onion flavor. Chive blossoms are often used as a garnish, but can also be tossed in a salad. Not only can you use chives for culinary purposes, but the plants make an attractive edible edging in the perennial border and the flowers can be cut for flower arrangements.


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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