California Planting Zones – USDA Map of California Growing Zones

The USDA plant hardiness zones are a useful tool for growers who want to grow certain crops or vegetables in different parts of the country. They were developed over 30 years ago by the U.S. Department of Agriculture (USDA) and they have been used ever since then. For example, if you live in Florida, you probably don’t need to learn much about growing tomatoes in Minnesota because all your local farmers will happily sell them to you.

However, if you live in Colorado Springs or Denver, it might make sense to learn more about the differences between their climates before deciding where to start growing tomatoes.

Growing zoned crops is not easy though; there are many variables that must be taken into consideration when planning a garden. You may even wonder how these zones could possibly apply to your particular area. Well, if you’re like most people, you’ve never really thought too deeply about it until now!

Zones are based on the average temperature and precipitation patterns throughout the year. So, if you live in Arizona, your growing season is longer than someone living in Missouri. That means that during the summer months, temperatures will usually be higher and rainfall rates lower. These are called ‘summer’ zones.

On the other hand, if you live in Minnesota or Maine, your average summer temperatures will be lower and you’ll probably experience heavier rainfall levels. These are called ‘winter’ zones. There are also two more factors to consider: fall zones and spring zones.

Zones are rarely split evenly between these four zones; instead they tend to overlap one zone into another as the seasons change. This means that even if you live in what would normally be a summer zone, you may still experience colder weather and shorter days during the fall.

One of the most important things to remember about growing zoned crops is that the zones are only general guidelines. There may be years where severe cold or heat persist through an entire season. Sometimes certain plants may not grow as well in hot weather and sometimes they may need more water than usual.

All of these things and more must be taken into consideration when planning out your garden, no matter what zone you decide to grow in!

California Planting Zones

Coastal Southern CA (Zone E) – This zone experiences less rainfall than other zones in the area, but there can be periods of droughts throughout the summer. Even though the coastal region is susceptible to fog, this type of weather does not last throughout the entire day. Coastal zones are usually exposed to stronger winds than the rest of California.

Coastal Northern CA (Zone R) – This zone experiences wetter weather patterns than the rest of California. The temperature here is also generally cooler, but there may be periods of extreme heat during the summer months. Precipitation is more common than the other zones and fog is a daily occurrence. You can expect snowfall during the winter months.

California Planting Zones – USDA Map of California Growing Zones - Image

Deserts of California (Zone D) – This is the hottest and driest zone in the state. Most of the land is mountainous or sandy with some scattered vegetation. During the summer, it isn’t uncommon to have over 100 Fahrenheit degree days! Precipitation usually takes the form of an thunderstorms and often arrives with powerful, damaging winds.

Foothills of California (Zone C) – The foothills are not as hot as the desert zones, but the summer days are usually warm and sunny. Winters here are generally mild, but there can be rainstorms that often pose a flooding hazard. Snowfall is uncommon except at the highest altitudes.

Mountain Valleys of California (Zone B) – Mountain valleys tend to have more extreme temperature fluctuations than other zones and can experience large amounts of snowfall. Spring tends to arrive later here and last longer in the fall. This is probably due to the surrounding mountains causing the weather patterns to behave strangely.

Northern California Mountains (Zone A) – The temperature here fluctuates greatly and there are large differences between daytime and night-time temperatures. Snowfall is common here, even during the winter months, and it can also get quite cold sometimes.

Central California Valleys (Zone A) – This weather pattern has similar temperature variations as the Northern California Mountains, except that it is slightly hotter and drier. Heavy snowfall is uncommon here and rain is less common than other areas.

Southern California Desert (Zone D) – The hottest and driest weather of all the zones usually occurs here. It doesn’t rain much in this region, with most precipitation taking the form of thunderstorms and other types of volatile weather patterns. There are periods of centuries that pass without any rainfall at all.

Southern California Mountains (Zone A) – The mountains of SoCal are usually a little colder than the rest of the zone, but snowfall is uncommon and usually melts within a few days. Rainfall is less common than the desert zones and the soil is usually rocky and hard to dig in for planting.

Sources & references used in this article:

Terrestrial vegetation of California by M Barbour, T Keeler-Wolf, AA Schoenherr – 2007 – books.google.com

Horticultural applications of a newly revised USDA Plant Hardiness Zone Map by MP Widrlechner, C Daly, M Keller, K Kaplan – HortTechnology, 2012 – journals.ashs.org

Mapping the risk of establishment and spread of sudden oak death in California by R Meentemeyer, D Rizzo, W Mark, E Lotz – Forest Ecology and …, 2004 – Elsevier

Development of a new USDA plant hardiness zone map for the United States by C Daly, MP Widrlechner, MD Halbleib… – Journal of Applied …, 2012 – journals.ametsoc.org

Limits to the potential distribution of light brown apple moth in Arizona–California based on climate suitability and host plant availability by AP Gutierrez, NJ Mills, L Ponti – Biological Invasions, 2010 – Springer

Progressive forest canopy water loss during the 2012–2015 California drought by GP Asner, PG Brodrick, CB Anderson… – Proceedings of the …, 2016 – National Acad Sciences

Potential energy savings in buildings by an urban tree planting programme in California by EG McPherson, JR Simpson – Urban forestry & urban greening, 2003 – Elsevier

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