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Colorado State University Extension offices like the one in Jefferson County bring the research and resources of the university within easy reach to our community.

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Horticulture Program

This page is your source for horticultural programs and class offerings through Jefferson County Extension.  You’ll also find many links to useful on-line resources!

Gardening Help

Master GardenerHave a gardening question?  Call the Master Gardener hotline at (303) 271-6632 to get personalized help with your specific situation.  You can also email questions and pictures to Master Gardeners at

You can also check our pest update blog for the latest landscape and garden problems reported to us.

The Plant Diagnostic Clinic is Open for only Drop-off and Mail-in Samples. Instructions for dropping off a sample can be found here.  Contact them with questions via email ( or phone (303-271-6627).

Samples may be dropped off anytime from 8:30am until 4:30 pm, Tuesday through Friday as we are closed on Mondays.  We try to complete your diagnosis within 5-7 business days. Fees apply.

Master Gardener Program

Jefferson County Extension will be offering an Apprentice Master Gardener Class in 2023.  To be added to the interest list, click on the link to “Jeffco Master Gardeners Interest List” in the list of resources at the bottom right of this page.  Applications will be emailed to those on the interest list in September 2022.  Additional information on the Colorado Gardener Certificate program and Green School Class (all of which are online) is available at the State Master Gardener Program webpage.

Demonstration and Research Gardens

Plant Select garden

Our on-site gardens are open to the public. The Plant Select garden offers beautiful displays of water-wise and climate tested plants.  There’s a kiosk in the garden containing information on the plants and their growing requirements.


The Horticulture Research and Demonstration Garden contains on-going studies including blueberry production, apple tree training, tomato and pepper variety trials and innovative vegetable garden season extension tools.  We are also developing an insectary garden to attract beneficial insects.

Web Resources

Keeping ahead of COVID-19

This rapidly evolving coronavirus (COVID-19) has imposed an unsettling, fluid situation upon our community and its businesses. While the team here still aims to maintain a “business as usual” approach, we are making a number of significant changes to our operations to account for a situation that is far from normal.