Ask the Master Gardener: Tips for Harvesting Rhubarb – Brainerd Dispatch

Dear Master Gardener: What is the best way to harvest rhubarb? Also, my neighbor told me that if my rhubarb has a flower, I’m supposed to break it off and I’m not supposed to pick and eat rhubarb after mid-July. Why?

Answer: Start picking rhubarb stalks as soon as they have reached their full length. Each variety is different and can vary approximately 1 to 2 feet in length. Hold the rod firmly, pull and twist. Immediately after harvesting, use a knife to cut the leaves from the stem. They are poisonous and leaving them on can cause the stems to wilt faster. The rhubarb harvest season lasts until the end of June. After this time, let the plant keep all of its leaves to build up energy for next year. It’s a common myth that the whole plant becomes poisonous later in the summer, but that’s not true. If you want to pull out a few stems occasionally later in the summer to prepare a dish, you won’t harm the vigor or health of the plant. The rods can however be harder.

Your neighbor is right about a flower stalk emerging from the plant. Cut it as soon as you see it. If the plant flowers and produces seeds, it will waste energy which should be stored for the next year’s harvest.

Dear Master Gardener: I would like to grow hollyhocks. Can I start them from seed right now?

Answer: Hollyhocks are those old-fashioned flowers our grandmothers used to grow and lately there has been a resurgence of interest in growing them. Like foxgloves, most old-fashioned hollyhocks are biennial, meaning they complete their life cycle in two years. First year growth results in a rosette of leaves near the ground. Growth in the second year results in stem growth, flowering and seed set, followed by plant death. Gardeners who grow hollyhocks often allow some of the plants to go to seed in order to get new plants each year. Some newer varieties are considered perennials, but they may not live more than a few years. If you cut the flowers right after they bloom so they don’t set seed, this will give the plants a better chance of coming back.

If you start hollyhocks from seed this year, you probably won’t see flowers until next year, and then they will most likely die. If you want flowers this year, you might want to get potted plants from a local garden center. Then let some plants drop seeds to get more plants in the future. Plant them in a sunny location and space them 12 to 18 inches apart.

Dear Master Gardener: Is it morel season? Where am I looking for them?

Answer: The morel is prized for culinary use and is probably the most recognizable and sought after edible mushroom. Morels usually emerge in the spring when there is sufficient rainfall. In southern Minnesota they can be found from late April through May and in northern Minnesota they can be found through June. Morels are most commonly found in woods or edges of woods. There is a common myth that they only grow near dead elm trees, but you can also find morels growing under or around rotting ash, oak, maple, poplar, and apple trees. It is crucial that you positively identify the mushrooms you pick and eat as there are poisonous look-alikes and some can be deadly. Here’s an old adage of mushroom pickers that’s good to follow: “When in doubt, throw it out.”

Dear Master Gardener: I would like to introduce my 5 and 7 year old children to gardening this year. Are there any books for kids this age that can teach them the basics of gardening at their level?

Answer: Yes, and what a great idea! Reading aloud to children is proven by research to help them develop a larger vocabulary, provide a fluent reading pattern, and encourage reading for enjoyment. Reading gardening books aloud to children can be beneficial for starting conversations about gardening. That’s actually how I started my love of gardening – my grandfather gave me a children’s book about flowers at a young age and then guided me through his flower gardens by taking me there. learning the names of flowers and telling me facts about them.

“From Seed to Plant” by Gail Gibbons is a wonderful resource with beautiful drawings that introduces elementary-aged children to the relationship between seeds and plants. “How a Seed Grows” by Helene Jordan helps children understand the difference between various seeds and how they grow into trees, fruits and vegetables. “A Seed is Sleepy” by Dianna Aston and Sylvia Long is a beautiful book that introduces children to fascinating facts about seeds and plants. Jerry Pallotta’s “The Flower Alphabet Book” not only introduces readers to different flowers, but works on unfamiliar letter sounds and pronunciation that children may not be familiar with before. There is also interesting information such as which flower is used to make a doll, which flower flavors the tea, and which flower growers feed the chickens.

Dear Master Gardener: What’s new on jumping worms?

Answer: Unfortunately, there are jumping worms in Minnesota. And, unfortunately, the jumping worms spread throughout the Minnesota Landscape Arboretum because they inadvertently used wood chips from an infected pile all over their garden beds, walking paths, and trees.

Jumping worms are an invasive species that move like a snake and sometimes appear to jump. It is identifiable by a flat, light-colored ring that extends around its body. They and their eggs can be distributed in commercial mulch or from community compost piles. They are able to survive in shredded pine, cedar and spruce mulch and have often been seen in mulched garden beds. No earthworm is native to Minnesota. Jumping worms are native to Asia and spread by moving potted plants, soil, compost, mulch, and fishing bait. They are able to quickly infest gardens and forest soils and will turn topsoil and mulch into dry, gritty granules that look like coffee grounds. They remove important nutrients from the topsoil, which, combined with the lack of an organic layer, kills weak plants and increases erosion. This means that invasive species like buckthorn can completely overrun an affected area. If your soil looks like coffee grounds and you find unusually active worms in your mulch, you may have jumping worms. Report any suspected jumpers to the DNR. Remove them and destroy them if you see them by sealing them in a bag and throwing it in the trash.

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.

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