Scheduling Vegetable Plantings for Continuous Harvest
By Janet Bachmann, NCAT Agriculture Specialist
Abstract
Market gardeners try to schedule their planting so they can offer customers a continuous supply of fresh flowers, herbs, and vegetables throughout the growing season.
Introduction
The best approach to planning for a continuous harvest is to keep good production records from previous growing seasons and to compare notes with other local growers. You also can find information in seed catalogs and Extension bulletins. You need to know, or be able to estimate:
- appropriate planting dates
- number of days to harvest
- length of harvest from first to last pickings
These factors are affected by several things. Weather, for example, is a major variable. Appropriate planting dates are commonly scheduled around the average annual frost-free date in the spring and the average annual first-freeze date in the fall. You can get these dates for your area from your local Extension agent or garden store. You can find a USA Frost Zone map here.
Weather has a large influence on timing because of its effect on seedling establishment and crop growth. For example, peas planted at the first possible planting date in the spring and then again two weeks later will usually mature only one week apart. Germination conditions at the time of the second planting will likely be much better, and the young plants will grow faster as the days lengthen, slowly catching up with the first crop. This same process happens in reverse for fall crops. Even a couple of days’ difference in midsummer planting dates can lead to a harvest date difference of two, or even three, weeks (Ogden, 1992).
Two ways to extend the harvest period for some crops are: 1) to plant varieties with a different number of days to maturity at the same time; and 2) to plant the same variety multiple times in succession.
Sweet corn often is grown in successive plantings to prolong the harvest season. A good way to stagger sweet corn plantings is to wait until one crop is 1 to 2 inches tall before planting the next. Sweet corn tends to emerge more slowly in cool soil (50–55°F) than in warm soil (68–77°F). Standard sweet corn varieties are better for early spring plantings than the super-sweet varieties, since the super-sweet varieties won’t perform as well in cool soil. Sowing sweet corn about one week before the average frost-free date is a rule of thumb for the very earliest plantings. On the tail end of the planting season, make your last planting about 80 days before the average first fall frost date. In addition to sequential plantings, you can plant varieties that require different lengths of time to reach maturity. For example, some sweet corn varieties are bred to mature in 70 days, while others require 100 days.
Planting in accordance with optimum soil temperature is another common way to schedule plantings. The table below, Soil Temperature Germination Ranges for Select Vegetables, provides a quick summary.
| Soil Temperature Germination Ranges for Select Vegetables | |
|---|---|
| TEMP (° F) | PLANT |
| 45–85 | cabbage, kale, broccoli, collards (germinate well at 85, seedlings prefer 45–65) |
| 35–80 | lettuce and most salad greens (at more than 80, germination rate drops 50%) |
| 35–75 | spinach (optimum 68) |
| 50–85 | onions (optimum 75) |
| 45–95 | radishes (optimum 85) |
| 50–85 | beets, Swiss chard (optimum 85) |
| 60–85 | beans, snap and dry (optimum 80) |
| 70–85 | beans, lima (optimum 85) |
| 40–75 | peas (optimum 75) |
| 60–95 | corn (optimum 95) |
| 65–82 | tomatoes (optimum 80) |
| 60–95 | peppers (optimum 85) |
| 65–100 | cucumbers, melons, squash (optimum 80–95) |
| Source: Market News, March 1995 | |
Insects and diseases are another major factor that can affect production scheduling. In the humid southeast, tomato growers often plant both spring and fall tomato crops because the early plants succumb to disease in mid-summer. A market gardener in North Carolina reports that she sets out tomatoes three times during the growing season. She also notes that squash vine borer is so bad in summer squash that she only gets about two weeks of harvest from each planting.
Abundance draws customers at farmers markets. Photo: Jim Lukens, SSAWG.
Once you have a framework of possible planting dates, you can work out your personal plan for successive plantings. The Succession Planting Chart below can be used as a template and adapted for your location.
A beneficial outcome of the Community Supported Agriculture movement, with its heavy emphasis on multiple crops and a continuous supply of customer favorites throughout the season, is the development of record-keeping and crop-planning systems geared to direct market farmers. A few of these can be found through the resources listed below. You can find many others in the ATTRA publication Community Supported Agriculture (CSA).
The ATTRA publication Market Gardening: A Start-up Guide also provides ideas and resources for vegetable planning and recordkeeping.
| Succession Planting | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| CROP |
seed
to flat, planned |
seed
to flat, actual |
plant
to field, planned |
plant
to field, actual |
esti-
mated days to harvest |
actual
days to harvest |
length of
harvest |
interval
between plantings |
comments |
| arugula |
30
|
2 weeks
|
best in cool weather | ||||||
| beans, bush |
60
|
2 weeks
|
summer | ||||||
| beans, lima |
65
|
*
|
summer | ||||||
| beans, pole |
60-70
|
*
|
summer | ||||||
| beets |
40-70
|
2 weeks
|
spring & fall | ||||||
| broccoli |
60-70 f.t.
|
2 weeks
|
spring & fall | ||||||
| cabbage |
70-80 f.t.
|
3 weeks
|
spring & fall | ||||||
| carrots |
85-95
|
3 weeks
|
spring & fall | ||||||
| cauliflower |
50-65 f.t.
|
2 weeks
|
spring & fall | ||||||
| collards |
60-100
|
*
|
fall | ||||||
| corn, sweet |
70-100
|
2 weeks
|
summer | ||||||
| cucumbers |
60
|
4-5 weeks
|
summer | ||||||
| edamame |
70
|
*
|
summer | ||||||
| eggplants |
65 f.t.
|
8 weeks
|
summer | ||||||
| kale |
40-50
|
2 weeks
|
spring & fall | ||||||
| kohlrabi |
50-60
|
2 weeks
|
spring & fall | ||||||
| lettuce, head |
70-85
|
2 weeks
|
spring & fall | ||||||
| lettuce, leaf |
40-50
|
2 weeks
|
best in cool weather | ||||||
| muskmelons |
80-90
|
2 weeks
|
summer | ||||||
| okra |
70
|
*
|
summer | ||||||
| onions, dry |
90-120 f.t.
|
*
|
|||||||
| onions, green |
85
|
2-3 weeks
|
|||||||
| greens |
30-60
|
2 weeks
|
best in cool weather | ||||||
| peas |
55-70
|
*
|
spring & fall | ||||||
| peas, southern |
65
|
*
|
summer | ||||||
| peppers |
60-70 f.t.
|
*
|
summer | ||||||
| potatoes |
90
|
*
|
spring & fall | ||||||
| pumpkins |
90-120
|
*
|
summer | ||||||
| radishes |
25-30
|
2 weeks
|
best in cool weather | ||||||
| radishes, daikon |
60-75
|
*
|
spring & fall | ||||||
| spinach |
50-60
|
2 weeks
|
spring & fall | ||||||
| squash, summer |
45-60
|
4-8 weeks
|
summer | ||||||
| squash, winter |
90-120
|
*
|
summer | ||||||
| tomatoes |
65-90 f.t.
|
2 weeks
|
summer | ||||||
| turnips |
35-40
|
2 weeks
|
best in cool weather | ||||||
| f.t. = from transplant | |||||||||
Reference
Ogden, Shepherd. 1992. Step by Step Organic Gardening. Harper Collins Publishers. p. 113-114.
Scheduling Vegetable Plantings for Continuous Harvest
By Janet Bachmann
NCAT Agriculture Specialist
Published May 2008
©NCAT
IP323
This publication is produced by the National Center for Appropriate Technology through the ATTRA Sustainable Agriculture program, under a cooperative agreement with USDA Rural Development. ATTRA.NCAT.ORG.
