Now you can grow a flower with petite pompom blossoms only an inch or two wide to dinner-plate size flowers that are16 inches across and can stop traffic! Dahlias, from the first seeds that went to Spain in 1789 from Central America and back again, the flowers have been spectacular. Blossoms can be single, like cosmos, cactus or semi-cactus, pompom, water lily and even like carnations or orchids or peonies. In addition to the great range of size and shape, the dahlia comes in almost every color and also in bi-colors and blends. The only color missing is blue! Native to Mexico, dahlias are popular as a garden and bedding plant and also as an exhibition flower. A member of a "tribe" of the composite family called Asteraceae, this "tribe" includes helianthus (sunflower), rudbeckia (black-eyed Susan), coreopsis and cosmos.

The dahlia was named in honor of a Swedish botanist, Andreas Dahl by Abbe Cavanilles of Spain. But in Eastern Europe the Russians and Germans changed the genus name to Georgina, in honor of a Russian botanist Professor Georgi. The flowers in the wild populations in Mexico are all single flowered but the seeds sent to France and Germany in the early 1800's produced doubles and semi-doubles. It is likely that these seeds came from garden plants, perhaps even from the Aztecs who were great gardeners. It was soon discovered that these plants easily changed their form, color and size and the double centered forms arrived quickly through hybridization.

With a little care, you can have beautiful dahlia blooms in your garden from July until frost. Dahlia tubers should be planted in full sun after all danger of spring frost has past. For better drainage our heavy clay soils need to be amended with sphagnum peat moss or compost. Use a low nitrogen fertilizer, such as 5-20-20 and feed monthly to encourage large blooms. The larger varieties will need some kind of support -either cages or stakes. Put these in place at planting time. Dahlias have shallow root systems so be careful when weeding or cultivating. Mulch with an organic mulch like compost or straw and water regularly keeping the water off the leaves.

When the plants reach 3 to 4 inches in height, pinch the terminal bud to produce two main stems. When the flower buds become visible it is time to disbud. If you are after the largest blooms, you want to keep the central leader bud and remove the two side buds. Removing the side shoots just below the main bud will result in an even longer stem. Flowers should be cut when they are fully opened. Cut early in the morning and immediately put the stem in water.

The trickiest part of growing dahlias is storing the tubers over winter. Frost will kill the foliage and you should cut that off leaving a three to four inch stem on the roots. Use a spade to lift the tubers out of the ground. Turn the tubers upside down to drain any water out of the stem and allow the soil to dry. Discard tubers that are diseased or damaged and dust cut surfaces with sulfur. Mark the tubers with a permanent marker with the name of the variety. Place the tubers in cardboard boxes that have a few inches of peat moss, vermiculite or sawdust in the bottom and cover with the same material leaving the stems exposed. Store in a cool, dry place at 40 - 50 degrees. Throughout the winter check the tubers for shriveling or fungus. Add a small amount of moisture if the tubers are drying up and remove any diseased tubers. In March or April the tubers come out of storage to start another season. Make sure each tuber has an "eye" before potting up. Dahlias can also be started from seed but this is mostly done with the smaller bedding dahlias and the resulting plants may not look like the original flower. And if all of this is too much trouble you can forget about digging up the tubers and buy new ones every year!

Q: I have roots growing along the surface of the soil around my ash tree, making it very difficult to mow around the tree. Is it OK to remove the surface roots, or will it damage the tree?

A: A large percentage of a tree's roots grow in the top 6-18 inches of soil. Depending on the species and soil condition, many tree roots may be found growing along the surface of the soil. Removing surface roots may harm the tree or make it unstable and susceptible to falling over in the wind. Since it is difficult to mow around the tree roots, you could try replacing the grass around the tree with an organic mulch. If you replace the grass with mulch, do not apply the mulch up against the tree trunk, as it will provide the perfect environment for fungal pathogens and over-wintering insects.

Q: No matter how much I weed, I can't seem to get rid of the weeds in my yard. Where are they coming from?

A: Some weeds are perennial, and if even a portion of the root system is left in the ground when pulled, the plant will happily re-sprout. Also, weed seeds can blow into your yard from surrounding properties, or the seeds may be dropped in your yard by birds and other wildlife. Another major source of new weeds is the existing weeds. A single pigweed plant, if allowed to go to seed, can produce over 100,000 seeds and a single purslane plant can produce 50,000 seeds. As if that isn't bad enough, those pigweed seeds can remain viable for up to 40 years, while the purslane seeds can remain viable for over 25 years. To be safe, it is best to remove weeds before they flower to prevent any unwanted fruit and seed production. Weed seeds also may be introduced when manure, or compost are added to the garden as soil amendments.

Q: I have recently been noticing yellow and brown spots on my lawn, usually with dark green borders. My neighbor says I should blame my new puppy. Could my puppy be ruining my lawn?

A: Animal urine, including that of dogs, contains fairly high levels of concentrated salts which can burn the grass, leaving "dead spots" in the lawn. Flooding these areas with water right after your dog relieves itself can help dilute the salts and prevent the dead spots from occurring; however, this is not likely to be a viable solution for most people. The other option is to train your dog to use a specific area of the yard, preferably an area with low visibility.

Q: Is it OK to compost diseased plants and weeds?

A: It isn't recommended that you compost diseased plants or weeds because the compost may not get hot enough to kill the weed seeds and disease organisms. It is also not a good idea to compost meat, bones, or dairy products, as these are usually slow to breakdown, can be quite smelly while decomposing, and may attract mice, raccoons, or other pests. You should also avoid composting animal feces, particularly if the compost is to be used on edible plants (for example your vegetable garden), as the feces may harbor harmful pathogenic organisms.

Bring some of your herbs indoors for the winter. Choose the most robust plants to move. Basil, oregano, sage and thyme are the easiest to grow indoors. They will need 5 hours of direct sunlight a day or supplement with artificial light. Water with tepid water and let the soil dry out between waterings. Fertilize once a month with a diluted houseplant fertilizer.

In the market for a new wheelbarrow? Look for heavy duty parts and a large diameter tire for better handling. Handles should be smooth and free of splinters and bolt holes should line up so the wheelbarrow is easy to assemble. For light loads of leaves and garden debris, a fold up model might be all you need and it won't take up much space.

You can still plant lettuce, spinach and parsley seeds for harvest next spring. The seeds will sprout and go dormant as the weather cools. Cover with a spun polyester row cover or a light mulch for winter protection. You'll be picking lettuce and spinach from your garden early next spring.

Aerate and fertilize your lawn this fall. Apply 1 pound of N (Nitrogen) per 1000 square feet to cool season grasses - bluegrass and turf-type tall fescue - while the grass is still green. Warm season grasses such as buffalograss or blue grama do not require a fall fertilization.

Pick up fruit that falls from your trees. Add it to the compost pile if it is free of disease and insects. It is also a good time to prune any suckers that have grown at the base of trees.

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:  September 21, 2004