The Effects of Altitude on Gardening in the Sierra
Gardening in The Sierra Nevada can be a daunting endeavor. As one ascends from the gently rolling foothills, the changes are quite stark with a steep climb beginning around 2,500 feet. It is straight uphill from Sonora all the way to the Sonora Pass, over 9,000 feet at its summit.
The air becomes cooler and drier as altitude increases. Carbon dioxide - necessary to all plants - is reduced as well. Plants then produce less oxygen, which is needed by pollinators and other insects. Wind increases the higher you travel, drying out the soil and atmosphere.
The growing season is much shorter at the higher altitudes of the Sierra. Often, freezing temperatures at night, even in the late spring, can kill plants, while the daytime sun almost fries them. Mountainous terrain results in more varied microclimates.
Microclimates are a help or a hindrance to the mountain gardener, depending on the gardener's skill in plant selection. The success of any garden depends on knowing plant needs in terms of temperature and water. Drought-resistant native plants will thrive on drier, hilly areas of the garden, while flowers and shrubs with greater water needs will be happier on flatter, more protected areas of the landscape. Creating rock gardens or raised beds are two ways to cope with dry, rocky hillsides because you can control the soil content.
Knowing what will grow in your area and what soil amendments you need help create an excellent environment for growing flowers and vegetables alike. Soil amendment is a must as you climb in altitude. Granite breaks down and causes flinty, sandy conditions in some areas, letting water runoff dry out plant roots. Other areas have hard clay soils with little drainage.
Although it may sound impossible to grow vegetables in the mountains, the opposite is true. When planting vegetables, raised beds with added organic material is the best way to provide improved soil and control water drainage. It goes without saying that protection from deer is an absolute must for vegetable gardening in the mountains.
Choose vegetables with the shortest days to maturity - leafy greens and root vegetables; carrots, turnips, parsnips, radishes and beets, to name a few. Start broccoli and other vegetables inside if they need to be planted after the last frost. Harden them slowly by exposing them to the outside gradually before transplanting them outdoors. Plant asparagus and beans after June 1st.
Look at the surrounding forest to see what kind of plants grow in your area. Plant some of these as mainstays in your garden and fill in the rest with natives and colorful annuals. There are many native flowers and shrubs that can make a mountain garden beautiful including manzanita, Sierra columbine, lupine and California poppies. Peonies, salvias, sedum, iris, daffodils and penstemon are other colorful choices.
Mountain gardens are more rugged but just as beautiful as gardens in the foothills. With a little extra planning and care, they can be also just as productive.
Sources consulted: "Sierra Yard & Garden" http://www.sierranevadaalliance.org/publications/SNLG/SNYG_lores.pdf J. Gale, 2004. Oxford Journals - Annals of Botany, vol. 94, Issue 2, Pp 199.
Francie McGowan is a Master Gardener who gardens above 4,000 feet in the Sierra Nevada Mountains.