Ask the Master Gardener: Now is a good time to tackle buckthorn – Brainerd Dispatch

Dear Master Gardener: I’m looking for projects I can do during this weird snowless winter. Is this a good time to remove buckthorn?

Answer: Yes, winter can be an excellent time to go after your buckthorn. It should be easier to identify buckthorn when everything is dormant so you can get a better look at the stems with their identifying “buck hoof print” tips: two terminal buds with a short thorn in the center. Buckthorn is the last thing to lose its leaves in the fall, and the first to leaf out in the spring. Look also for any remaining clumps of glossy dark berries. Although not toxic to birds they do have a laxative effect so probably aren’t the birds’ first choice for a snack.

Small shoots can be pulled by hand if the ground isn’t completely frozen. Larger plants can be cut near the base and daubed with either a glyphosate or triclopyr amine solution. Check the label to make sure the temperature is warm enough to be effective. Then cover the stump with either a tin can nailed in place or wrap the stump in black plastic and tie it on. Monitor the area at least once a year so you can keep pulling new shoots. Five-year-old buckthorn seeds can still germinate and the birds may be bringing in new seeds.

A newer method of removal that is chemical-free and would be easy to start in the winter is called critical period cutting or CPC. Identify your buckthorn now with paint or ribbons. Once the plant has begun actively growing, cut it off, leaving a four-to-five-foot stump. As it leafs out again, strip off the new growth. Do this a couple more times this summer and next. With no leaves for photosynthesis, the plant will eventually deplete the energy reserves stored in its roots and will die. The following year the stump should be easy to remove, maybe with just a good shove!

Dear Master Gardener: I have seen packages of paperwhites in stores. What are they and are they supposed to bloom at this time of year?

Answer: Paperwhite narcissus (Narcissus papyraceus) are in the Amaryllis family, native to the Mediterranean, and fun to grow indoors at this time of year. I am forcing hyacinth bulbs right now and it is like having a touch of spring in my home! First, choose firm, healthy bulbs. To force them use a low, shallow container with no drainage holes. Line the bottom with clean, washed pea gravel or small stones. Place the bulbs close together, pointed end up, on the gravel. Then add enough gravel around the bulbs to keep them in place. Do not cover the bulbs — leave their noses exposed. Fill the container with just enough water to touch the bottoms of the bulbs and maintain that level until you discard them when they are done blooming. Place the container in a cool, dim spot while roots form and shoots begin to appear. When shoots are about 3 inches tall, move the container to a warm, sunny place. Flowers will appear in 2-3 weeks — some people like the distinctive fragrance and some hate it. The long stems tend to flop so prepare to be creative in ways to stake or tie them together. Research shows that water containing 4-6% alcohol (gin, vodka, etc. but not beer or wine) helps prevent flopping.

Dear Master Gardener: My peace lily looks sick and no longer flowers. What can I do to save it?

Answer: According to some surveys, peace lilies (Spathiphyllum) are America’s favorite houseplants, probably because they require very little light and tolerate neglect. They have long, glossy green leaves and dramatic white flowers. However, like all living things, they thrive with some pampering. While they do well in low light, they grow and flower best in bright, indirect light. They like to be slightly rootbound and hate standing in water. They are prone to root rot and fluoride toxicity but not much else. If your lily does not bloom, cut back on the watering, doing so only when the soil surface is dry. Usually, failure to bloom means there is too little light and too little humidity. Do what you can to correct both. Because some people like the foliage but not the flowers, cultivars have been created that do not bloom, and if your plant has never bloomed, you may have one of those. Because peace lilies grow wider, not taller, they need to be repotted every two years or so. At that point divide and repot them in any good potting soil in pots only one inch wider than the divisions. Peace lilies are native to the rain forests of Central and South America and are related to Anthuriums, Philodendrons, and Canna lilies.

Dear Master Gardener: My Schefflera has yellow speckles on the underside of the leaves. Is it getting a disease?

Answer: It sounds like your plant may have spider mites. The first sign of a spider mite attack is usually a mottled or pin-prick yellow discoloration on the underside of the foliage. Spider mites are hard to see with the naked eye. They typically live and feed under the leaves and spin a fine, white web, which eventually can cover the whole plant. They are actually not true insects, but related more to spiders and ticks. Spider mites are a serious problem and can multiply quickly, eventually defoliating and killing the plant. They thrive in dry environments. Because they can enter a home on Christmas trees and greenery in December, this is a good time to be periodically checking your houseplants.

To find out if you actually have a spider mite problem, place a white sheet of paper under the mottled leaf and tap on it. If you see tiny moving creatures on the paper, you know you have a problem. If the infestation is light you can try washing the leaves of the plant. If the plant is small enough you can place it in the sink and spray it with warm water to dislodge the pests. On a larger plant you can use a soft, soapy cloth to wipe the leaves then rinse them with warm water. For serious infestations, you can use bifenthrin, insecticidal soap, or plant oil extracts. Spray your plant on both sides of the leaves in a well-ventilated area, and keep it out of direct sun for one day after treatment. It is important to read the labels on pesticides very carefully before buying and using the product. If the spider mites persist, you should destroy the plant.

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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