Growing food by zone

Start with your zone, then look past it

The USDA hardiness zone map tells you how cold your winters get. Zones are based on the average annual extreme minimum temperature from 1991 to 2020. They run from zone 1 (coldest) to zone 13 (warmest), each 10°F wide, and each is split into an “a” (colder) and “b” (warmer) half. ¹

Use it to choose perennials: fruit trees, berries, asparagus and anything else that has to survive the winter. But USDA is clear about its limits: ¹

• It shows average lows, not the lowest ever, so a rare cold snap can still kill plants.
• An early fall freeze or a warm spell followed by a sudden freeze can injure plants even in the “right” zone.
• It doesn’t capture frost pockets in low spots or warm spots near buildings and pavement.
• It covers winter cold only. Summer heat, moisture, wind, soil and sunlight matter as much.

For planting dates in your area, ask your county extension office for its local planting calendar.

Plan rows from real yields

Gardens fail on wishful thinking. The UC Master Gardener Program publishes typical yields per 15-foot row. Some crops are measured as two rows on a raised bed, which yields more per foot of garden. ² For example:

Crop	Yield per 15 ft row
Potatoes, white	36 lb
Tomatoes	42 lb
Squash, winter	45 lb
Carrots (two rows on a raised bed)	40 lb
Beans, snap (bush)	15 lb
Onions, bulb (two rows on a raised bed)	34 lb

New growers and poor sites often get 25 to 50% less. ⁴ Our land and garden calculator turns what your household eats into row feet and garden area, with a yield setting to account for this.

Plant the slow things first

Trees take years. Dwarf apple trees bear in 2 to 3 years, semi-dwarf in 4 to 5 and standard trees in 7 to 10. ³ Peaches and sour cherries bear in about 3 years, sweet cherries in 5 to 7 and plums in 6 to 7. Stress from poor drainage, pests or disease can delay that. ⁸ That’s why fruit trees belong in your first year, alongside water and shelter.

Stretch the season

A high tunnel is an enclosed structure covered in plastic or fabric, with crops grown in the native soil or in low raised beds. NRCS says it can extend the growing season by raising soil and air temperatures, and protects crops from sun, wind, heavy rain and cold. NRCS’s standard calls for at least 6-mil UV-resistant greenhouse plastic and a frame at least 6 feet tall at the peak. ⁵ NRCS offers financial help with high tunnels through its Environmental Quality Incentives Program (EQIP). Ask your local USDA service center. ⁹

University of Kentucky’s high tunnel calendar puts it simply: growers can plant earlier in spring and harvest later into fall. On cold, cloudy days, plants survive but don’t grow much. ⁶

How much land for a whole diet?

Vegetables are only part of what you eat. A peer-reviewed study of ten U.S. diets found each person needs 0.13 to 1.08 hectares of farmland a year, about 0.32 to 2.67 acres, including grazing land, depending on the diet. ⁷ Unless you have that much good land, plan to buy or trade for staples such as grain and oil at first, and grow the vegetables and fruit yourself.

Sources

1. USDA ARS, Plant Hardiness Zone Map: How to Use the Maps
2. UC Master Gardener Program, Approximate Yields
3. University of Maine Cooperative Extension, Rootstocks and Dwarf Fruit Trees
4. Utah State University Extension, Expected Vegetable Yields in Utah
5. USDA NRCS, High Tunnel System, Conservation Practice 325
6. Knight J, Rudolph R. High Tunnel Planting Calendar (CCD-FS-9). University of Kentucky Center for Crop Diversification, 2019
7. Peters CJ et al. Carrying capacity of U.S. agricultural land: Ten diet scenarios. Elementa, 2016
8. Oklahoma State University Extension, Fruit FAQs
9. USDA NRCS, EQIP High Tunnel Initiative