Ask the Master Gardener: Dishing on making the perfect dish garden

Dear Master Gardener: I would like to make a dish garden. How do I do it and what plants are best?

Answer: Dish gardens with succulents and cacti continue to be very trendy. They are great for those who enjoy having houseplants but are forgetful when it comes to watering them. The term succulent refers to a broad category of plants, which include cacti. They have thick fleshy leaves or stems that serve as water storage organs to ensure survival under arid conditions. Succulents do not require much water or fertilizer, but they do need bright light. In nature most succulents grow in well-drained sandy soil, so those conditions need to be duplicated when grown indoors. You can either purchase a potting mix specifically for succulents or mix equal parts potting soil and sterile coarse sand. Most importantly, make sure there are drainage holes in the pot because excess water trapped in the soil will rot the plants very quickly.

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Succulents are often grouped together in a shallow dish. Depending on the size of your container, choose an odd number of plants that are compatible in growth rate and look good together. As a general rule, cacti need less water than other succulents. Plants to consider include: jade plant, snake plant, aloe vera, echeveria, kalanchoe, hens and chicks, cacti, haworthia, sedum, agave, and string of pearls.

Dish gardens with succulents are low-maintenance, but there are a few things to keep in mind. During winter, only water succulents (including cacti) enough to prevent shrinking and withering. Frequent shallow sprinklings will often result in distorted growth, so when you water, do it thoroughly, allowing water to flow out the drain holes. Always allow the soil to completely dry out between watering sessions. Fertilize cacti at half-strength once or twice a year with a houseplant food that is higher in phosphorus (middle number) than nitrogen. The best time to do this is late spring or summer. Other succulents should be fertilized at half-strength three to four times during spring and summer.

Dear Master Gardener: Are cashews really in the same plant family as poison ivy?

Answer: Yes, they really are! Cashews and poison ivy, as well as mangos and pistachios, are in the botanical family Anacardiaceae, also known as the sumac or cashew family. When you purchase cashew nuts at the grocery store, they appear to be raw but they are not and you will always find them shelled. Like poison ivy and poison sumac, the cashew tree produces a toxic resin called urushiol. The nut itself is perfectly safe to eat but if it comes in contact with any part of the shell during harvest, it will give the person who eats it a nasty rash. To remove this resin, cashews go through a rigorous steaming or roasting process to make sure they are safe to eat.

The Center for Disease Control reported an incident that occurred in April 1982 when 54 people experienced poison ivy-like rashes after eating cashew nut pieces sold by a Little League organization in Pennsylvania. The bags of cashew pieces were imported from Mozambique and processed by a Pittsburgh company. When bags of cashews were opened and inspected, it was discovered that about 36% contained pieces of cashew shell. For those unlucky people who purchased and ate cashews from the contaminated bags it would have the same effect as mixing poison ivy leaves with the nuts.

Dear Master Gardener: I purchased a beautiful, lush peace lily plant about four weeks ago and a few days ago about one-third of the leaves started turning yellow. What am I doing wrong? Will the yellow leaves turn green again if I correct the problem?

Answer: The peace lily (Spathiphyllum) is an attractive houseplant with lovely long-lasting, white flowers. These plants prefer medium light, but not direct sunlight, and will develop yellow leaves if they are not getting enough light or they are getting direct sunlight. Another cause of yellowing leaves is too little or too much water. If the leaves start drooping, your plant needs water. It is quite common though to overwater plants, which is the number one mistake people make with houseplants. Let the plant dry out between watering sessions and make sure the pot is not sitting in water. Unfortunately, the yellow leaves will not turn green and healthy again, even with tender loving care. Prune off leaves that have turned yellow or brown and prune off flowers when they turn brown.

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Dear Master Gardener: Which trees should I protect from sunscald over the winter? Should I wrap them with brown tree wrap?

Answer: Young trees, newly planted trees, and thin-barked trees (cherry, crabapple, honey locust, linden, maple, mountain ash, and plum) are susceptible to sunscald. The University of Minnesota Extension recommends wrapping the trunk with white commercial tree wrap or plastic tree guards to reflect the sun and keep the bark at a more constant temperature. The U of M does not recommend using brown paper tree wrap or black colored tree guards because they will absorb heat from the sun. Put the wrap on now and remove it in the spring after the last frost.

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 umnmastergardener@gmail.com 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.