Dear Master Gardener: Now that Christmas is over, how do I take care of my poinsettia?
Answer: Here are tips from the University of Minnesota Extension to keep your poinsettia healthy all year long:
- Keep your plant in a bright window or under a grow light.
- Allow your plant to dry out between waterings.
- Fertilize your poinsettia with an all-purpose houseplant fertilizer at half the recommended strength about once a month as long as you continue to see new growth.
- Check your plant for signs of insects and treat if necessary.
- Prune off faded and dried parts of the plant.
- If you start to see roots on the surface of the soil, consider repotting or add a little potting soil to cover them.
Dear Master Gardener: Are there any elm trees we can grow that are resistant to Dutch elm disease?
Answer: American elms were widely planted throughout the United States, but unfortunately were devastated by Dutch elm disease in the 1960s and most did not survive. Dutch elm disease is a fungus that was introduced around 1930 and was spread by elm bark beetles. Because American elms were planted close together in urban environments, it made it easy for the fungus to spread. Researchers at the University of Minnesota have been working hard to evaluate trees that are resistant to Dutch elm disease. The new varieties have been found to grow quickly and need a tremendous amount of care and pruning during the first 15 years. Prairie Expedition was developed by North Dakota State University in 2004 and is hardy to zone 3. It has the classic vase-shape that the American elm is known for, with outstanding autumn gold color. It has a fast growth rate and reaches a mature size of 45 feet in height and 30 feet in width. Another elm that is hardy to zone 3 and has good disease resistance is Discovery. It is very slow growing and smaller than Prairie Expedition, reaching a mature height and spread of 35 feet by 30 feet. It has proven to be stress and drought tolerant, too. Elms hardy to zone 4 with good to excellent disease resistance include: Accolade (excellent), Danada Charm, Commendation, Cathedral, Jefferson, New Harmony, St. Croix, and Triumph.
These trees take considerable pruning and training in the first 15 years, which will determine how well they will perform for the remainder of their lives. Like most trees, they are best maintained with a strong central leader to ensure a straight stem and keep the tree growing up rather than out. As the lower side branches grow and increase in diameter, they should be removed until the desired clearance for the site is reached.
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Dear Master Gardener: I would like to grow a fig tree as a houseplant, but I hear they are finicky. When I went to the garden center to look at them, I discovered there are lots from which to choose. Is there one that is easier to grow than another? Also, do they produce edible figs?
Answer: Ficus species are often grown as houseplants and have a variety of leaf textures and sizes. Most of them become large plants creating a bold accent. Here are some popular choices:
- Ficus elastica (rubber plant) has oblong leathery leaves and an erect single stem habit when young. Older plants branch and develop woody stems. Ficus elastica ‘Decora’ has broader, larger, heavier leaves with prominent, depressed veins and red new growth. Ficus elastica ‘Doescheri’ is a variegated type with streaks of gray, white, and creamy yellow. Its midrib and leaf stalks are pink.
- Ficus lyrate (fiddleleaf fig) sports huge, waxy, dark green leaves that have attractive yellow-green veins. It requires constant moisture or the leaves turn brown and drop.
- Ficus benjamina (weeping fig) has small, shiny, deep green leaves on pendant branches. Ficus benjamina ‘Exotica’ (Java fig) is an attractive cultivar that has slender arching branches with pendulous tips. It has glossy green, leathery leaves that have a slight twist at the tips. I always consider Ficus benjamina to be a real drama queen - you move it across the room and it drops all its leaves. It hates change, or even a draft. Once it’s happy and you leave it alone, it will grow like mad.
All Ficus species like bright, indirect sunlight. Most foliage plants need constant moisture but never wet conditions. Frequency of watering depends on the size of the plant and container. Figs thrive in high humidity — 40% relative humidity is a minimum for good growth. They are susceptible to dry air, drafts, and dust, so keep them away from drafts and try to maintain humidity around them. Occasionally clean the leaves. During active growth, fertilize monthly with a water-soluble fertilizer. Ficus are prone to scale, aphids, and mealybugs. None of the above-named Ficus produce edible figs.
Growing an edible fig tree in a container could be fun and rewarding, but it’s important to have realistic expectations. Like growing citrus trees in containers, you will likely only get a few fruits from a healthy fig tree. It is probably best to buy it in late spring. Then, when there is no threat of frost, acclimate it to a sunny location. Grow it outside all summer and before the first killing frost, bring it indoors for the winter. Figs need to go through a dormant period in the winter to stay healthy. Don’t panic if the leaves turn yellow and drop. Once your fig tree is indoors, reduce watering significantly making sure the upper two inches of potting mix are dry before watering again. The size of the plant and pot, the type of potting mix, and the indoor temperature will determine how often the plant needs watering. It may only need watering every one or two weeks. It is extremely important not to over water a dormant fig or it will get root rot and die.
