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SMB Frost-Free Growing Seasons   arrow

In San Miguel Basin & Surrounding Areas

And the Hardiness of Vegetables and Flowers

Microclimates vary widely in the mountains.  Often, the tops of sloping areas absorb more heat from the sun and allow cold air to drain off and so are a bit warmer than low-lying areas where frost can settle and are colder.


CommunityDates of average ‘Frost-free’ Growing SeasonComments   Frost Free ‘Growing Seasons’ are based on average (50% chance) last 32.5⁰ F frost in the spring and first 32.5⁰ F frost in the fall.   **See Colorado Climate Summaries for official weather station data.  
NorwoodJune 9 – September 21 (104 days)**The newest data reduced this by a week for first fall frost. 
RedvaleBeginning of June through September/October*May have slightly longer season with warmer daytime temperatures than Norwood*
NuclaBeginning of June through September/October*Somewhat cooler than Naturita but warmer and longer season than Norwood*
NaturitaBeginning of June through September/October*Warmer, longer season than Norwood*
Paradox EastMay 14- September 24 (133 days)** 
Paradox WestMay 8-  October 5 (150 days)**Paradox/Bedrock have two weather stations
TellurideJune 28 -August 31 (64 days)**  Some locals use June 15th as the average last frost. **
PlacervilleJuly 19- August 15 (27 days)**This is a short-season for an area referred to as the ‘banana belt’*.  I question the reliability of this data.  There seems to be a problem on the graphs.
Mountain Village/Ophir There isn’t any official data for Mountain Village or Ophir.  Local input would be valued.
UravanMay 2 – October 13 (164 days)**No town there but there is a weather station, and this is the longest frost free growing season in the area!
RicoJuly 1- Aug. 31 (61 days)** 
RidgwayJune 21- September 8 (79 days)**Ridgway can have hard freezes in the summer months* (Ridgway Community Garden)
OurayMay 29 – September 26 (120 days)**Locals traditionally plant out on Memorial Day weekend *
SilvertonJuly 12 – August 15 (34 days)**This is a big change (from9 to 34 frost free days) from past data
*Anecdotal, based on local opinion, not data—can still be valuable Information
**Data from 50++ years from weather stations (1948-2005)


Hardy annual flowers**Tolerate cold soils and light frostsCan plant out 4 weeks before average last spring frost datePansies, snap dragons, sweet alyssum, calendula, dusty miller, poppies, ornamental kale and cabbage
Half-hardy annual flowersTolerate cool soils but not frostsCan plant outside 2 weeks before average last spring frost dateGeranium, dianthus, lobelia, ageratum, petunias, gazanias
Tender annual flowersNeed warm soil and don’t tolerate frostsWait to plant outside 1-several weeks past last average spring frostZinnia, salvia, begonia, coleus, vinca, impatiens
Perennials Check hardiness ratings and pair with your hardiness zone 
* Annuals complete their lifecycle in a single year.  They won’t come back from the roots or crown the next year, but they may re-seed. 
** Cool season annuals may decline in summer heat.


Cool-season hardy annual vegetables*Can tolerate 24-28 degrees FCorn salad, arugula, spinach, broccoli, Chinese cabbage, kale, kohlrabi, turnip, parsnip, salsify, brussel sprouts, fava beans, leeks, garlic, some onions
Cool-season semi-hardy annual vegetables*Can tolerate 28-32 degrees FBeets, carrots, cauliflower, lettuce, onion, peas, radishes, spinach, Swiss chard, endive, radicchio, kale, mustards
Warm-season annual vegetables that do not tolerate frostCannot tolerate temperatures <32Beans, corn, peppers, eggplants, melons, pumpkins**, winter squash**, tomatoes***, melons***, pumpkins***
Warm-season annual vegetables that do not tolerate frost<50 degrees F decreases qualitySweet potatoes, basil
* Don’t do well in heat of summer—plant before last frost date or leave in garden after first frosts and have better quality when grown with light frosts.
** Can withstand some light frosts if followed by warm day temperatures
*** Ripen further after harvesting when semi-ripe.

This Informational Sheet was compiled by Yvette Henson, Extension Director and Agriculture, Natural Resources and Horticulture Agent for San Miguel Basin.  For other Fact Sheets or information on growing ‘High and Dry’ (at high altitude with water limitations) come by our office at 1120 Summit Street (across from the Fairgrounds) in Norwood, call (970) 327-4393, email or or visit our website at

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Colorado State University Extension es unproveedor que ofrece igualdad deoportunidades.
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