How to Choose the Best Seeds for California Gardens

For avid California gardeners, January marks the beginning of planning spring or summer  gardens and ordering seeds. Seed availability and turnaround time for orders is usually best early in the year, in January through early February, before the national seed-ordering rush begins from about February through April when most of the United States begins to emerge from winter cold and to prepare for spring and summer gardening.

Whether you prefer online or paper catalogs, choosing appropriate seeds can be confusing. What is the important information in the catalogs? And how can you tell what varieties will work in your specific area? To skip the confusion, and for an environmentally friendly shortcut to success with no paper catalogs needed, visit GardenZeus, enter your zip code, and browse plants for recommended seed varieties that have been vetted and approved by GardenZeus experts specifically for your California zip code. Many of our recommended varieties are linked directly to vendor websites.

GardenZeus generally recommends open-pollinated, untreated, organically grown seeds, with exceptions for specific or challenging situations, such as hybrid tomato seeds when high yields are needed in limited space. For descriptions of common terms used to describe seeds, such as open-pollinated, heirloom, hybrid, genetically modified, treated and pelleted, see Deciphering Common Terms for Garden Seeds.

For those of you with spring seed catalogs on your desk beckoning, here is some guidance.

When selecting seed varieties, pay attention to the plant’s overall dimensions, the size of the flower or vegetable, and a description of the foliage for leaf vegetables and ornamentals. The description may also contain other relevant characteristics, such as “slow bolting” or “heat tolerant.”

Seeds catalogs usually list number of days to first harvest or bloom, sometimes listed as just a number (70 days), and usually meaning the average number of days from the time the seed sprouts or the seedling emerges from the ground to the time fruit or flowers can be harvested. If you are planting in new or infertile soil, are new to gardening or inexperienced with the vegetable or flower that you are planting, or working under challenging gardening conditions, the actual time to maturity may be longer than listed in seed descriptions, and in some cases much longer. To arrive at the total number of days from planting the seed to maturity, you need to add the germination time, which varies widely for different vegetables and flowers but is most commonly about a week or two.

Many seed descriptions indicate a variety’s resistance to specific diseases, more often for hybrids which naturally tend to be more disease-resistant than open-pollinated varieties. For example, resistance to powdery mildew, a critical consideration for cucurbits in California’s coastal areas, might be listed as (PM). For a description of codes and abbreviations, check the index to the seed catalog or appropriate website.

For seeds of perennial plants, descriptions typically list the USDA zone in which the variety grows. USDA zones are inadequate for making informed decisions about what to grow in California because they are based on average annual minimum winter temperatures only, and do not take into consideration other critical factors for California gardening and landscaping, such as summer and winter high temperatures, annual rainfall, humidity, overall climate and seasonal changes in climate, or the number of days annually of hot weather or frost. The USDA zones put portions of Los Angeles in the same zone as San Francisco, despite the vastly different growing conditions, temperature ranges, climates, and high temperatures between those two cities. For this reason, GardenZeus uses a climate zone system optimized for California and for your individual zip code. To take complete advantage of GardenZeus resources for California gardening, go to GardenZeus, enter your zip code and select plants. For a complete explanation of GardenZeus climate zones, go to California Climate Zones.

GardenZeus has comprehensive, customized growing information by plant and zip code. To get started, enter your zip code here.

Did you know that many soils in California are more alkaline than is ideal for a variety of commonly grown plants? The following articles discuss soil pH in the home garden:

Mud Pies and Fizz: Easy Home Tests for Soil pH

Tips for Testing Soil pH at Home With a Soil Ph Meter

This is an updated version of an article originally published on January 26, 2018.