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Seedy Language: Understanding Garden Jargon by Dennis Hinkamp
Enthusiasm may override common sense when it comes to planning a garden based on seed catalogs and Web sites. For example, something often noted is "USDA cold hardiness zone." Cold is a relative term, so what does this mean? In the simplest terms, the USDA has defined standardized zones, ranging from 1 to 11, for all areas in the United States as an aid to determine if a plant will survive in that area, said Taun Beddes, Utah State University Extension horticulturist for Cache County. For instance, Cache Valley is generally a zone 4 or 5. Zone 4 means that an average minimum temperature is between 20 and 30 degrees below zero while the average minimum temperature for zone 5 is between 10 and 20 degrees below zero. Lower zone numbers indicate colder areas.
"I have noticed that some catalogs list hardiness zones higher than they actually are," Beddes said. "It is also common for catalogs to state that a plant is more cold hardy than it actually is. A plant I commonly see this with is Crape Myrtle, which is a shrub or tree popular in warmer areas. It has a long bloom season and very ornamental bark. Some varieties of this plant are commonly listed as being hardy to either zone 5 or 6. However, when they are planted locally, they are regularly killed back to the ground by the cold."
Also be aware of claims pertaining to how well a plant grows, he said. Statements such as, "survives almost anywhere," could be interpreted as, "you will never be able to get rid of this plant once it is placed in the yard."
Another claim commonly seen in tree descriptions is how wonderfully fast a species may grow, said Beddes. If you read, "grows at least 10 feet a year; provides instant shade," be very cautious. This statement may be more properly worded, "will grow fast but die quickly due to insect pests and diseases, and it may cost several thousand dollars to remove."
A final issue not generally listed in catalogs is soil requirements of plants, Beddes said. Plants such as rhododendrons, azaleas, dogwood trees, silver maples, red maples and blueberries do not perform well in Intermountain West soils, even though they are among the most popular ordered.
As with anything, it is always wise to use caution if you do not know exactly what you are ordering, he said. "I recommend using reference books to learn more information about a particular species," he concluded. "USU Extension has many publications and resources relating to proper plant selection. Local, experienced nursery personnel can also be a helpful resource."
Commonly advertised plants to be weary of in garden catalogs
These shrubs are common east of the Mississippi and the West Coast. They bloom gloriously. In garden catalogs they are advertised as being low maintenance, and that many varieties are hardy to northern climates. This is true. What the descriptions do not account for is that they are not adapted to our dry climate and alkaline soils. They suffer from iron chlorosis, lacking the ability to absorb enough iron the soil. The vast majority planted locally struggle or fail. I know of a few hobbyists growing them, but they are a lot of work and need constant attention.
Crape myrtles are shrubs or small trees grown in warmer areas of the United States. They love heat and are only hardy to around 0 degrees Fahrenheit at best. Locally, they are commonly killed to the ground in the winter. A few survive planted around buildings protected from winter cold and with loads of reflected heat.
Hybrid Willows and Cottonwoods:
These are often advertised as the "fastest shade available". They grow from 6 to 10 ft a year. However, faster growing trees have weaker and more brittle wood. They additionally grow up to 50 to 60 ft high and wide. With most modern homes being built on lots as small as a tenth acre, they are very unsuitable. Plant in areas with room and away from structures and vehicles.
Sugar and Red Maples:
These are advertised as being solid shade trees with wonderful autumn colors ranging from orange to red. This is true but, they also suffer from iron chlorosis locally. In bench areas, I see them have a better chance, where the soil is often not quite as alkaline.
These suffer from iron chlorosis and have an accelerated growth rate, making the wood somewhat brittle. These are less commonly planted than they were several years ago.
Star-of-Bethlehem bulbs have beautiful white spring flowers. They are also drought hardy and able to naturalize over large areas. Reinterpreted, this means that the plant spreads rapidly throughout the yard and is almost impossible to control. I have seen people go to the extent of sifting their soil to remove the bulbs. This is partially effective but the plants produce seeds that are too small to sift out. The only herbicides registered for control are expensive and tricky to use. The only other solution is soil solarization.
Hardy Kiwis and Hardy Figs:
These species are advertised as being suitable for northern gardens. The kiwi still seems to struggle in Utah where I have only spoken with a few gardeners that have grown them successfully. The figs are more manageable if they are planted in an area where they receive lots of summer heat and protection from extreme winter cold. It still may be necessary to wrap the trunk in insulating foam or excavate enough roots on one side of the tree so that it can be laid down and covered in leaves or other light textured well-draining mulch.