How to Plan Next Year’s Vegetable Garden

1. Look back at this year

Clemson’s January advice for South Carolina starts with three questions: which vegetables did you eat the most, what did you grow too much of, and which pests did you fight? Oregon State says to keep a garden journal and consult it in winter, and Iowa State says to keep a log, a map, a diagram or a photo of where everything grew — you will need it for step 2.

If the soil has not been tested, January is a good time: Clemson says the results show whether you need lime or other nutrients, and Oregon State says your local extension office can give you a list of laboratories.

2. Rotate by plant family

Iowa State University Extension and Outreach says vegetables in the same botanical family often share the same diseases and insects, and many diseases persist in the soil for years. Do not plant the same family in the same place for 3 to 4 years, or 5 or more if you can. Wisconsin gives the same three to four years, and says even a simple change from one year to the next helps.

In a small garden

• Make separate beds. Iowa State says three or four raised beds make rotation straightforward; one plot split into zones works less well, because digging it all at once mixes soil and spreads disease between zones.
• Use containers for especially disease-prone vegetables, such as heirloom tomatoes (Iowa State).
• Trade with a neighbor. Each grows one or two families and you swap the harvest, then switch families the next year (Iowa State).
• Mind cover crops and weeds. Iowa State says they belong to the same families and can host the same pests.

3. Sort the seeds you already have

Clemson says to inventory leftover seeds and toss any that were not stored properly. University of Illinois Extension says some seeds keep for years and some do not: parsley and onion are short-lived, while melons, cucumbers and cabbage can last five years or more.

Iowa State says those years assume ideal storage and do not replace a germination test.

Test before you buy

1. Roll seeds in a damp, not soaking, paper towel. Illinois uses 10; Iowa State says at least 20, 50 is better and 100 is best.
2. Put the roll in a plastic bag labeled with the seed and the date, and keep it somewhere warm.
3. Check every few days. Iowa State waits until a week passes with no new sprouts, then divides the sprouted seeds by the seeds tested.
4. Read the result. Iowa State calls 90% or more very good, and 70 to 80% acceptable for small or abundant seed. Illinois says at 70 to 90% sow more thickly than the packet says.

For big seeds — peas, beans and corn — Illinois’s Brittnay Haag drops them in a bowl of water: “If they sink, they are still viable; if they float, they are garbage.” Iowa State tests about a month before planting.

To keep seeds, Iowa State says a sealed glass jar in a cool, dry place such as a cool closet, root cellar or refrigerator; Illinois suggests paper envelopes or glass in the refrigerator, and a seed swap with friends.

4. Order early, and try something new

Texas A&M AgriLife says to place seed orders in December to get the varieties you want, and to try a few new kinds each year. Cornell says to order in the fall to be certain the varieties are still available, and Utah State and Clemson both suggest working through the catalogs for new vegetable varieties. Utah State adds that herbs and microgreens can be grown indoors in the meantime.

5. Put dates on it

A plan needs dates, and those depend on your nearest weather station, not your state. Our four tools count each date from your own station’s NOAA freeze normals:

• When do I start my seeds? — the spring calendar: what goes indoors, what goes out, and when.
• When do I sow the next round? — how often to re-sow each crop through the season, and which sowings summer heat makes pointless.
• What can I still plant? — late in the season, which crops still have time to mature.
• What survives my winter? — fruit trees, berries and perennial vegetables for your hardiness zone.

The zone-by-zone view is in when to start seeds indoors by zone, and the month’s other jobs are in January garden jobs by zone. If you plan around moon phases or almanac best days, see planting by the moon: what the evidence says.

Planting dates by zone, crop by crop: Tomato, Pepper, Lettuce, Carrot, Potato, Onion, Cucumber, Zucchini and Squash, Bean, Pea, Spinach, Broccoli, Kale, Cabbage, Cauliflower, Beet, Radish and Sweet Corn.

Planning fruit: which types suit your zone and winter chill, fruit by fruit: Blueberry, Strawberry, Raspberries and Blackberries, Fig, Apple Tree and Grape.

Common mistakes

• Forgetting where things grew. Without a log or map, rotation is guesswork (Iowa State).
• Rotating crops, not families. Tomatoes after peppers is the same family in the same soil (Iowa State).
• Sowing old seed at the packet rate. Test it first, and sow more thickly if the rate is down (Illinois).
• Storing seed somewhere warm or damp. Keep it cool and dry (Iowa State, Illinois).
• Ordering late. Popular varieties sell out (Texas A&M AgriLife, Cornell).