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Delivering a first-rate transportation system for Seattle Scott Kubly, Director







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Typical Traffic Calming Measures
Neighborhood Speed Watch Program
Participation in the Neighborhood Traffic Control Program
2006 Traffic Circle Construction
Traffic Circle Maintenance
Traffic Circle Trees & Plants
Studies and Reports
Resources and Related Sites

Traffic Circle Maintenance

Proper maintenance is key to the success of any planting, but is particularly critical for traffic circle gardens. Though "drought resistant" plants are prevalent in the list of recommended plants, no plant can withstand drought conditions until it is properly established. Follow the minimum maintenance tips below to ensure your plantings flourish!


Plants cannot live without adequate soil moisture; and traffic circles are like big plant containers that dry out quickly as they are particularly exposed to heat and wind. After giving your plants a good soaking immediately following planting, it may be necessary to water a couple of times during the week during dry spells. Even a rain shower may not soak into the ground deeply enough to reach roots. You should be able to feel moisture in the soil 3-4 inches down. If not, then it's time to water. To reduce plant disease and water loss to evaporation the best time to water is early in the morning before it gets hot. If this is not possible, water whenever you are available. Recruit one or two traffic circle buddies who can water when you are unavailable. Often corner house residents gladly provide access to water for the traffic circle.

Weed Control

Weeds compete with desired plants for moisture, nutrients, and light and make the traffic circle look messy. Hand weeding works great and should be shared by neighbors who can enjoy a good visit among the plants and flowers. Regular weeding will keep the traffic circle easy to manage and looking its best!

If herbicide is used, we suggest that only the target weeds be treated using "Round-Up." Use a brush or spray carefully so that you avoid contact with desired plants. Pesticides contribute to soil, water, and air pollution and should be used carefully and selectively.


Fertilizer should not be necessary for plant establishment. Use of a slow release or an organic fertilizer may be applied using the manufacturer's recommendations. April and October are the best times to apply. Remember that excessive use of fertilizers can burn plants and pollute our lakes and streams.

Plant Replacement

The City of Seattle does not have the funding to provide replacement plants on a regular basis should your circle be damaged or suffer from neglect. We may be able to assist with limited replacement. Call SDOT Urban Forestry at 684-8733 to see if surplus plants are available. Otherwise, it is the neighbors' responsibility to replant appropriately.

Safety When you are working in your traffic circle, be aware of cars. Face on-coming traffic and keep tools on or in the traffic circle. Brightly colored clothing will help you to be more visible to drivers. Rocks and furniture are not permitted in traffic circles. Be safe and have fun!

Important Planting Tips!

For more information, call SDOT Urban Forestry at 684-8733.

  • Arrange plants in the circle, plant the largest plants first, then the smaller ones.

  • Before planting, remove all plants from their containers and any other wrappings. Containerized plants should have their roots "ruffled" before planting.

  • Be sure to plant trees and shrubs so that the trunk flare is above ground. Plant trees in the center of the circle, or at least 3 feet from the yellow warning signs. See New Tree Planting for a thorough description.

  • Firm soil around the roots (use shovel handles to gently tamp soil around trees & larger plants).

  • Fertilizing at the time of planting is not necessary, but a light application of a slow release fertilizer is fine.

  • Thoroughly water plants at the time of installation so that root balls get a good soaking. Follow up with weekly watering, or as needed, for the first three years during the dry season, May - October. The rule of thumb for watering trees is at least 5 gallons for every inch of truck diameter as often as necessary.

  • Mulching with compost, beauty bark, or wood chips is encouraged and should be applied and maintained by the Traffic Circle volunteer to a depth of two inches to minimize weed growth, loss of moisture, and improve fertility.

  • Clean plant containers may be reused by garden centers.

  • Neighbors may supplement the plantings with bulbs or other appropriate plant material. NO ROCKS OR POSTS MAY BE PLACED IN A TRAFFIC CIRCLE!

  • Click here for Seattle Public Utilities brochures on Natural Lawn & Gardening practices.
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