Ask the Master Gardener: Propagate that Ruby Necklace and share it with friends - Brainerd Dispatch | News, weather, sports from Brainerd and Baxter

Dear Master Gardener: I made a succulent dish garden this past winter and one of the plants, Ruby Necklace, has gone crazy and is trailing across my table. It needs a trimming! Can I propagate it and share it with friends?

Answer: Ruby Necklace, also known as Little Pickles (Othonna capensis), is a fast-growing, delightful succulent. Yes, it can be propagated from stem cuttings. Using a pruner, cut a 3- to 4-inch-long piece of stem and let it dry for a day or two to form a callus. Then plant it in a pot with succulent potting mix. Water it sparingly until roots develop, which may take a few weeks.

Dear Master Gardener: Orange spots have turned up on the leaves of some of the perennials in our garden. What is it and what should we do about it?

Answer: It sounds like you have a common fungal disease called rust, which can affect many different plants in the flower garden. The fungus needs water on the surface of the leaves to start growing, so this may have turned up on your plants due to all the rain. Overhead watering can also cause rust and other fungal diseases, so using soaker hoses or drip irrigation will help alleviate that problem.

Rust can detract from a plant’s appearance, but rarely does significant damage to the health of the plant. Pinch off infected leaves and remove them from your garden. Do not remove more than one-third of the plant’s foliage at one time. According to the University of Minnesota, fungicides are rarely necessary to manage rust in a home garden and should only be used to protect valuable plants that cannot be replaced and have a history of severe infection. If using a fungicide, only apply it to healthy green tissue early in the growing season before infection begins. Examine the lower leaves of plants with a history of severe rust once a week. When the first spot is observed, pinch off the infected leaves and begin a fungicide spray to protect healthy tissues. Repeat applications if necessary, according to label instructions. Fungicides will not cure or remove existing rust infections. Once most of the leaves have spots, it is too late to treat the plant.

Dear Master Gardener: We have had two hardy hibiscus plants for years. This year one did not come up and the other looks stunted. What could have happened?

Answer: Hardy hibiscus plants are slow to come up in the spring, but should have made an appearance by now. If one has emerged and looks stunted and the other has not shown up, my best guess is that the cold temperature spells with the lack of snow cover may have caused the stunted growth of one plant and death of the other. Many gardeners in Minnesota have reported losing some perennials this year. I lost a Pulmonaria, three Primula, and a few Lady in Red ferns. Losing plants is so disappointing!

Dear Master Gardener: Should Nicotiana be deadheaded?

Answer: Yes, Nicotiana sylvestris (flowering tobacco) should be deadheaded to encourage more blooms and reduce self-seeding.

Dear Master Gardener: Is a Kentucky coffeetree a good replacement for ash trees?

Answer: Kentucky coffeetree (Gymnocladus dioicus) is native to southeastern Minnesota and uncommon throughout its North American range. It is rare because its hard, impervious seed coat makes it very resistant to natural germination. Due to its limited range and small natural populations, it was listed as a Minnesota Special Concern species in 2013. It is propagated and planted in urban and rural landscapes and recently has become a popular species used to replace ash and elm trees. Kentucky coffee tree is dioecious, which means it has either only male or female flowers. Both male and female flowers are small and white, but female flowers develop into large, hard seedpods. Cultivars have been developed of male trees that will not produce the somewhat messy fruit. The University of Minnesota has released two cultivars of Kentucky coffee trees, Stately Manor and True North. Stately Manor was released in 2002 and is a male specimen (no seed pods) that reaches 50 feet high and 40 feet wide. It tolerates a wide range of soil conditions and has unusual, deeply furrowed bark that adds winter interest. True North is also a male specimen, notable for its narrow, upright-oval form, superior branch architecture, and lack of fruit and seeds. It reaches 50-70 feet high and 20-30 feet wide. It was released in 2015. Kentucky coffee tree is hardy in zones 3-8.

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 [email protected] 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.