Gardening In Lassen County

Climate Zone and Elevation

The area that encompasses most of Lassen County is an area of extreme variations in elevation and growing season.  Spring weather may fluctuate from sub-freezing at night to the upper 60’s and 70’s in mid-afternoon.  Many areas have up to a 130 day growing season with temperatures in the summer reaching in the 90’s and occasionally over 100.  Other areas have less than 60 frost-free days, such as the Madeline Plains area of Lassen County, and frost can be expected in some years any months of the year.

Most gardening books, catalogs, and seed packets refer to plant hardiness zones, climate zones, or growing zones.  Twenty-four climate zones are defined in the Sunset Western Garden Book, and most of Lassen County is in Zone 1A & 2B.  Twenty zones are defined by the United States Department of Agriculture (USDA).  Lassen County ranges from Zone 6A to 7A.  Zone 6B is the reasonable compromise for most of the area.  These cold zones translate into a short growing season.  

The last frost date varies considerably year to year and by location.  Typically the last frost is around the end of May the first frost falls around the end of September, which gives just a four-month growing season.  July temperatures average 58 – 66.  Most root crops – beets, carrots, onion sets, garlic, and potatoes – produce beautifully if planted as soon as the ground can be worked.  Most cool season leafy vegetables that can be harvested before they mature can be grown successfully.

Some crops may be planted somewhat earlier if frost protection is afforded them.  Usually, hot caps or water sleeves are used for frost protection.  Starting vegetable seeds indoors has advantages if one has the time and a little know-how.  By starting vegetables indoors six to eight weeks before planting time, the growing season can be extended and less seeds can be used. Seed loss in the garden is usually due to climatic conditions, weeds, birds, insects, and disease.

Every gardener soon learns that there is no such thing as a normal growing season in Lassen County.  A 130 day growing season may be 150 days one year and 100 days the next.  “Last frost dates” published by the weather bureau are “normal” or “mean” dates.  It is a date one-half way between the earliest and latest frost dates of the spring season.  There is a 50 percent chance that it will come earlier or later.