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News for Norther Colorado and the world

Thursday, November 26, 2015

Master Gardeners, hedges to grasshoppers (again)

Hedges for Landscapes

By: Dick Christensen
Colorado State University Extension Master Gardener in Larimer County

Formal hedges with bench– Photo by Dick Christensen

Would you like to get away from it all in your own backyard? A hedge can establish private outdoor spaces enclosed by leafy textures. In the most complete sense of the word, a hedge is any barrier or boundary composed of plants or stone. A hedgerow refers to small fields separated by hedges. In Colorado, hedges usually are rows of bushes or small trees planted closely together. A hedge can be short, tall, sculptured or left to mature naturally.

In addition to providing privacy, the living fences of hedges can create outdoor rooms that also provide habitat for birds and other wildlife. Hedges can create windbreaks, trap snow, and screen unsightly views. Decorative or formal hedges are regularly sheared or pruned to precise sizes and shapes, while informal hedges grow naturally with only occasional shaping. To create an appealing formal hedge, gardeners must commit to frequent maintenance. If left unattended for too long, the hedge may grow wild and require a few seasons of care to be fully restored.

Before planting, study the size of the mature plant and plan for appropriate spacing.  Then calculate the length and width needed to accommodate the hedge several years in the future. If planting along a wall or existing fence, factor in enough space behind the mature hedge to allow for “backstage” pruning.

How to Prune Hedges

A well-maintained hedge provides a boundary to a garden, but if left unchecked, a hedge can soon lose its shape and cast unwanted shade. With a good pruning schedule, you can keep hedges under control without too much effort.

The best way to prune hedges is to create a base that is wider than the top of the hedge. This is also known as the inverted keystone effect; it allows the bottom of the hedge to receive sufficient sunlight and air circulation. A hedge which is pruned evenly, top to bottom may look appealing but may compromise the health of plants. For hedges planted from shrubs, prune to encourage lateral branch growth, clipping away branches and protrusions that deform the shape of the hedge.


  • Hand shears are fine for small forms, but if it’s a long hedge, invest in an electric, battery, or gas-powered hedge trimmer. It will make lighter work of the job.
  • When trimming, keep the cord away from the blade, ideally draped over one shoulder, rather than trailing on the ground. If you use an electric trimmer, make sure it’s plugged into a safety socket fitted with a residual current device or circuit breaker, so that the engine will cut out if the extension cord is accidentally cut (this happens—have a spare cord on hand).
  • Keep hand shears sharpened and let the tool do the job it was designed for, rather than trying to cut with blunt blades.
  • Wear appropriate protective equipment, such as goggles and gloves.

Formal hedges

  • Decide if you prefer to start by pruning the top flat or shearing side growth first.
  • When cutting the sides, make the top narrower than the base.
  • If the branch growth isn’t too long, you should be able to cut by eye, stepping back occasionally to check your progress. If you don’t trust your eye, hammer two stakes into the ground and stretch a length of string between them to use as a cutting guide.
  • Brush off trimmings from the top of hedge and from the base of the hedge to prevent the spread of fungal diseases.

Informal hedges

  • Although informal hedges that flower—such as lilac—are allowed to grow naturally, they still require occasional pruning. If neglected, they could soon grow too tall or spread out of their allotted space.
  • To keep them in good shape, occasionally remove old stems with pruners or cut branches to keep within bounds.
  • Be sure to prune at the appropriate time of year for the shrub.  For example, lilacs and forsythia should be pruned after blooming.

Dwarf hedges

  • Low-growing hedges used for ornamental parterres, knot gardens, or as borders around vegetable beds can be kept neat by trimming three or four times a year.
  • Cut lavender, boxwood, and germander in spring and in midsummer.
  • Use string stretched between two stakes to ensure that the top is flat and then cut the sides vertically.

Suggested Plant Material

Plants commonly used for hedges include privet, boxwood, and lilac, but just about any plant, hardy to zone 5, can be used for a hedge. Location and size can be limiting factors in plant selection.

The two main categories of hedge plants are evergreen and deciduous. Evergreen hedge plants will retain the foliage year-round and will therefore serve as screens or shields even during winter. A risk with evergreen shrubs is that heavy snow may break top branches and kill the plants. Deciduous hedge plants will lose their leaves in the winter, making them less susceptible to snow damage, but also less useful as a screen.

When making plant selections, consider height, attributes and use.  Study growth properties such as density, sun or shade tolerance, soil types, and drainage. Also give thought to wildlife attraction, flowers, or good fall color.

Plants, based on height, are listed below.  Note: Plants suitable for formal shearing are in italics.

Deciduous hedges 3’ or shorter

Barberry, Boxwood, dwarf varieties of spirea and viburnum, Potentilla.

Deciduous Hedges 3’ to 6’ tall

Alpine Currant, dwarf Euonymous, dwarf Lilac, dwarf varieties of Privet, chokeberry, dwarf ninebark, dwarf dogwoods, serviceberry, spirea, compact viburnum and forsythia.

Deciduous Taller than 6’

Cheyenne privet, Peking cotoneaster, dogwoods, Euonymous, lilacs, Amur maple, Vanhoutte spirea, viburnums, honeysuckle, pussy willow, and siberian pea shrub

Fortunately, there are many hedges from which to choose. An excellent site for comparing hedges in full growth is at Colorado State University’s Plant Environmental Research Center (PERC), located at 630 West Lake Street in Fort Collins on the southwest corner of CSU.

Gardening Tips

By: Mitzi Davis
Colorado State University Extension Master Gardener in Larimer County

1.  The ripening stages of tomatoes are immature, mature green, breaker, pink and red. Mature green stage fruits have a white to yellow star at the blossom end. Most supermarket tomatoes are picked at the mature green stage and ripened with ethylene gas. The breaker stage is when the blossom end is pink and the tomatoes at this stage will ripen naturally. Tomatoes at the breaker or pink stage will ripen in five to seven days at 65-68 degrees F.

2.  Oregon produces nearly all of the hazelnuts (filberts) in the United States. The trees are biennial—one year each fruit cluster will produce a single nut, and the next year the tree will have more than one nut per cluster. The nuts drop from trees in fall. In larger orchards, nuts are harvested with a vacuum that picks them up and blows out any debris. Hazelnuts are eaten raw, roasted, covered in chocolate, made into hazelnut butter or gianduju – a hazelnut, chocolate spread.

3.  Composting requires the right combination of “greens” (nitrogen-supplying material) and “browns” (dried plant material that supplies carbon). Think lasagna! The brown layer may consist of dried leaves, dried hay and straw, paper and lint. You will need twice as much brown material as green. The green layer will have food scraps (but no meat!), garden waste and grass clippings. Sprinkle on a little soil to add microorganisms and repeat the layers. Keep moist, turn after a week and then once a week until the pile freezes. By spring you should have beautiful compost to incorporate into your flower and vegetable gardens.

Gardening Q&As

By: Vonne Zdenek
Colorado State University Extension Master Gardener in Larimer County

Q. What is the situation with the numerous grasshoppers in my yard? Is there anything I can do about them?

A. The numerous grasshoppers in yards may persist until there is a hard frost. Grasshoppers are some of the most difficult insect pests to control, since they are so mobile. There are over 100 species in Colorado and their food habits vary. Many feed on grasses or sedges, others prefer broadleaved plants. The problem ones are those that feed on garden and landscape plants. In the vegetable garden, they will eat lettuce, carrots, beans, sweet corn and onions. Grasshoppers rarely feed on trees or shrubs, however in a year like this, they may. There have even been reports of them chewing holes in window screens.

Natural predators include adult robber flies and many birds, such as horned larks and kestrels. They are also frequently eaten by coyotes.

But what can we humans do? The good news is that experts can predict grasshopper populations. Homeowners should watch for the nymphs and spray insecticide. The bad news: the timing for this year has passed and now we must deal with the adults. Some insecticides may be applied directly to the plants being eaten, however plants may be harmed. The choice of insecticides is limited since few allow direct application to garden fruit and vegetables.

Insecticides that can be used carefully on vegetables now are carbaryl and permethrin. These have many trade names. Other chemical grasshopper controls must be used before the pests become adults. Whenever dealing with edible crops, always follow the manufacturer’s recommendations for applying insecticides in relation to harvest intervals.

More information is available at the Colorado State University Extension web site at

The authors have received training through Colorado State University Extension’s Master Gardener program and are Master Gardener volunteer for Larimer County.

Larimer County is a county-based outreach of Colorado State University Extension providing information you can trust to deal with current issues in agriculture, horticulture, nutrition and food safety, 4-H, small acreage, money management and parenting. For more information about CSU Extension, Larimer County, telephone (970) 498-6000 or visit

Visit PlantTalk Colorado ™ for fast answers to your gardening questions! PlantTalk is a cooperation between Colorado State University Extension, GreenCo and Denver Botanic Gardens

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