Gardening in Larimer County

Good plants don't just "happen."  The annuals, perennials, and vegetables you buy at your local garden store often represent years of breeding research. Even then, success is still not guaranteed. Plants that perform well in some areas of our country can do poorly in Colorado's challenging environment of high intensity light, alkaline soils, wind, and fluctuating temperatures. So how do you know which plants will perform best in your garden?

Fort Collins is fortunate to be the site of several trial gardens that offer an opportunity for the public to view new and established varieties of annuals, perennials, trees and shrubs. A seven-acre arboretum, a perennial garden, annual flowerbeds, and a vegetable garden are open to the public at the W.D. Holley Plant Environmental Research Center (PERC) at 630 W. Lake Street in Fort Collins. In 2001, the annual trial garden made its debut at its new site in front of the old Fort Collins High School at the intersection of Lake St. and College Ave. This year the annuals can be viewed at both new and old sites. By 2003, the new site should be finished so that all the annual trial garden entries are conveniently at one place.

The PERC annual trial garden began as an All American Selections (AAS) display garden in the late 1970's. Later Colorado State University expanded the trials to include seed and cutting varieties from the world's top breeding companies. Five years ago, the garden was chosen as a national test site for AAS flower trials.

All American Selections is a non-profit organization dedicated to trailing and promoting the very best seed grown plants. Every year since 1932, breeders have entered new flower and vegetable seed into these national trials. There are 33 AAS trial grounds with display gardens in 19 different states not including Canada. Each garden has an impartial judge who rates the flower entries for color, disease  resistance, uniformity, uniqueness, fragrance and length of bloom. Vegetables are rated for flavor, yield, appearance, disease resistance, nutrition and even novelty. The entries are coded and the source of seed kept anonymous to ensure impartiality. Each entry is compared to an industry "standard," a similar plant already available to the public.

Winners are those plants with the highest average score after all judges have submitted their findings. Before the awards are announced, the seed producer is required to produce a sufficient amount of seed to satisfy demand. This can take up to three years or longer. Look for the red, white and blue emblem that denotes an AAS winner when you make your flower and vegetable purchases.

If hardy, top performing perennials are your preference, visit the PERC perennial garden. This garden has been in existence for more than twenty years. The mature heights and widths, length and color of bloom and plant habit can be viewed before deciding to purchase the plant.  Or tour the garden to get great ideas for plant combinations. Just west of the perennials is the newer ornamental grass garden planted in 1999. Data is taken yearly on each plant's performance in both these gardens.

The arboretum at PERC not only provides a place for a shady stroll, but also serves as a long-term trial site for trees and shrubs. The varieties planted have had minimal care except for watering. The plants are allowed to grow into their natural form, without corrective pruning. Trees and shrubs that are not well acclimated to our climate show signs of stress like dieback or chlorosis. Some varieties one would not expect to do well are thriving. The PERC arboretum is an excellent place to get ideas for your garden.

Visiting your local trial gardens can be fun, informative, and inspiring! After seeing plants perform well regardless of the rigors of our environment, you will have the confidence to choose some new plants for your garden.

Question: If this drought keeps up, what annuals can I plant next year that are xeric?

Answer:  There are many annuals that require less water than a blue grass lawn once established. The following list is only a few: Spider flower (Cleome hassleriana), dusty miller (Senecio cineraria), gazania (Gazania rigens), gloriosa daisy (Rudbeckia hirta), moss rose (Portulaca grandiflora), verbena hybrids, vinca (Catharanthus roseus), zinnia (especially Zinnia angustifolia), petunia hybrids, and mealy cup sage (Sa/viafarinacea).

Question:  Do hummingbirds like petunias? I think I see one sipping from the flowers in the evening.

Answer:  What you are seeing is most likely the hawk moth or hummingbird moth. These large moths can be seen at dusk and dawn sipping nectar rich tubular flowers like petunias. The moths hover like the hummingbirds but are not brightly colored. The larvae of these moths are the infamous tomato and tobacco hornworms.

Question: Why is there a dark, wet stain on the trunk of my elm tree? Insects seem to be very attracted to this.

Answer:  Your tree probably has bacterial wetwood. This condition is not uncommon in large elms and cottonwoods, as well as other trees. Wetwood may occur in the trunk, roots, and branches. It is thought to be caused by anaerobic bacteria that inhabit the non-living portions of the tree. Internal pressure from bacterial activity forces it out of cracks or wounds in the tree. Fungi, yeast and bacteria grow in this discharge making it very attractive to insects. Wetwood has no known cure and is considered a nuisance or cosmetic problem. Reduce stress to your tree especially in times of drought by providing adequate deep watering. Also, keep an eye on the structural integrity of the tree.

Question: Earwigs are collecting in the saucers of my containers and underneath the pots. How can I get rid of them?

Answer:  Earwigs hide during the day in dark, sheltered places. At night they can feed on young plants and flowers. However, they are also predators of aphids, insect eggs, and larvae providing a natural control against garden pests. Regardless of their fearsome looking pinchers or cerci, they are not harmful to humans or animals. If the earwigs are not significantly harming your plants, leave them alone. Otherwise you can trap them by providing wet newspapers, burlap, or boards for them to hide under. Collect and relocate or destroy them. Insecticide baits and sprays are also available at your local nursery.
 

Late July is the time to start seeding pansies for bloom this fall.

If young trees are producing too much fruit, thin them to produce larger fruit and to lessen the weight of the branches.

Trim grass around fruit trees as the grass can deprive trees of needed nutrients.  This will also help prevent injury to the trunk from lawn mowers and weed whackers.

Save lawn clippings and spread a 2-3inch layer of them under taller established plants. This helps prevent weeds, conserves moisture, and adds organic matter to the soil.  Be sure and dry the grass before using it as mulch as the wet grass will mat.

In late July, slow down watering cabbage to prevent heads from splitting.

The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.

Gardening and Insect Fact Sheets are available on-line by clicking HERE.

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This page updated:  March 17, 2003