Vegetable Planting Guide

pdf logoPrint this CMG GardenNotes

green line
green line

Cool Season Vegetables

These vegetables prefer cool growing temperatures (60°F to 80°F) and lose quality in hot weather.  They are often replanted mid-summer for fall harvest.

Hardy Vegetable

Crops: broccoli, cabbage, kohlrabi, onions, lettuce, peas, radish, spinach, turnips

Temperatures: Hardy vegetables grow with daytime temperatures as low as 40°F and may survive a frosty nip.

When to plant:

  • Based on soil temperatures, refer to Table 2
  • Plant as soon as soil adequately dries in the spring.
  • These crops may be planted as early as two to four weeks before the date of the average last spring frost. 

Semi-Hardy Vegetables

Crops: beets, carrots, cauliflower, parsley, parsnips, potatoes, and Swiss chard

Temperatures: Semi-hardy vegetables grow with minimum daytime temperatures of 40°F to 50°F, but are less tolerant of a frosty night.

When to plant:

  • Based on soil temperature.
  • Plant as soon as soil adequately dries in the spring.
  • These crops may be planted as early as zero to two weeks before the date of the average last spring frost.

Warm Season Vegetables

Warm season vegetables require daytime temperatures above 60°F. They prefer summer-like weather with temperatures between 70°F and 95°F. They are intolerant of frost and may be sensitive to cool spring winds.

Tender Vegetables

Crops: beans, celery, corn, cucumbers, New Zealand spinach, and summer squash

Temperatures: Tender vegetables grow with daytime temperatures above 55°F, and are intolerant of frost.

When to plant:

  • Based on soil temperature, refer to Table 2.
  • Soil is adequately dry to work.
  • These crops may be planted (from seed) around the date of the average last spring frost.  Transplants of cucumbers and summer squash should be delayed until the time listed for the very tender group below.

Very Tender Vegetables

Crop: lima beans, cantaloupe, eggplant, pepper, pumpkin, winter squash and pumpkins, tomato, and watermelon

Temperatures: Very tender vegetables are not only intolerant of frost, but also cool spring winds.  They need daytime temperatures above 60°F, and prefer temperatures of 70°F to 95°F. A week of daytime temperatures below 55°F may stunt the crop.

When to plant:

  • Based on soil temperature, refer to Table 2.
  • Soil is adequately dry to work.
  • These crops are typically planted two plus weeks after the average last spring frost date.
  • Weather is becoming summer-like, (i.e., consistently above 55°F (daytime) and breezes should have lost any cool nip.



Table 1.
Vegetable Planting Guide
Vegetable
Cool Season Crops3
Beets
40°
80°
90°
4-6”
¾-1”
7-10
60
 
Broccoli
40°
80°
90°
18”
½”
3-10
65T
5-7 a
Cabbage
40°
80°
90°
18”
½”
3-10
85T
5-7 a
Carrots
40°
80°
90°
2-3”
¼”
10-17
70
Cauliflower
40°
80°
90°
18”
½”
3-10
65T
5-7 a
Kohlrabi
40°
80°
90°
7-9”
½”
3-10
50
Leeks
40°
80° 
90°
4-6”
¼”
7-12
120
Lettuce (leaf types)
35°
70°
70°
7-9”
¼”
4-10
60
Onion, green
35°
80°
90°
2-3”
¼”
7-12
60
Onions, dry (seed)
35°
80°
90°
4-6”
¼”
7-12
110
Onions, dry (sets)
4-6”
1-2”
Parsnips
35°
70°
90°
5-6”
½”
15-25
70
Peas
40°
70°
80°
4-6”or 3” x 8”
1”
6-15 
65
Potatoes
45°
12-15”
4-6”
125
Radish
40°
80°
90°
2-3”
 
½”
3-10
30
Spinach
40°
70°
70°
4-6”
½”
6-14
40
Swiss Chard
40°
85°
95°
7-9”
1”
7-10
60
Turnips
40°
80°
100°
4-6”
½”
3-10
50
Warm Season Crops
Beans
50°
80°
90°
6” or 4” x 12”
1-1½” 
6-14
60
Cantaloupe
60°
90°
100°
36-48”
1-1½”
3-12
85
2-3 b
Corn
50°
80°
100°
12” x 30” or 9” x 36"
1-1½”
5-10
60-90
Cucumbers
60°
90°
100°
6” trellised 24-36” untrellised
1”
6-10
55
2-3 b
Eggplant
60°
80°
90°
18-24”
¼”
7-14
60T
6-9 c
Pepper
60°
80°
90°
15-18” 
¼”
10-20
70T
6-8 c
Tomato
50°
80°
100°
trellised: 24”  between plants
¼”
6-14
65T
5-7 c
Squash, Summer
60°
90°
100°
36-48”
1-1½”
3-12
50
2-3 d
Squash, Winter
60°
90°
100°
36-48”
1-1½”
6-10
100
2-3 d
Watermelons
60°
90°
110°
36-48”
1-1½”
3-12
85
2-3 d

1  Germination temperature – Soil temperature is one of the best methods to determine spring planting time.  Plant when soils reach minimum temperature measured at 8 a.m., 4 inches deep. Beans are an exception, being measured at 6 inches deep.  Optimum temperatures listed in the table are useful for starting seeds indoors.  Maximum temperatures are listed in regards to high soil temperatures that may interfere with seed germination in the summer.

2  Plant spacing – Spacings given are equal-distance spacing for crops grown in block or close-row style beds.  For example, beets, with a spacing of 6 inches are thinned to 6 inches between plants in all directions.  In other words, beets are thinned to 6 inches between beets in the row and 6 inches between rows.  The closer spacing listed should be used only on improved soils with 4-5% organic matter. Close-row or block style planting works well for raised bed gardening, with blocks/beds 4 feet wide (any length desired) and two-foot wide walkways between blocks/beds.

a. Cool Season Crops – Cool season crops prefer a cool soil.  Lawn clipping and newspapers make an excellent mulch for these crops by cooling the soil, preventing weed germination and conserving water.  Apply fresh grass clippings only in thin layers (less than half-inch) and allow it to dry between applications.  Thick layers will mat and smell.  Do not use clipping from lawns treated with weed killers or other pesticides.  Several layers of newspapers covered with grass clippings also work well between rows.  Do not use glossy print materials.

b.  Transplanted cole crops – Since cole crops (cabbage, cauliflower, broccoli, and Brussels sprouts) germinate better in warmer soil, they are typically started from transplants in the spring.  Days to harvest are from transplants.  In the warmer areas of Colorado, these crops produce the best quality when direct seeded mid summer (early July for the Front Range area) for harvest during cooler fall weather.  Before planting out, harden off seedlings.

c.  Transplanting vine crops – Vine crop (cucumbers, squash, melons) roots are extremely intolerant of being disturbed, and perform best when grown by direct seeding rather than by transplants.  With the use of black plastic to warm the soil, direct seeded crops germinate rapidly.  If using transplants, select small, young plants, not more than two to three weeks from seeding. 

d.  Tomato family transplants – The tomato family is traditionally planted from transplants.  In warmer areas of Colorado, they can also be direct seeded with minimal delay.  Days to harvest are from transplants.


Average Frost Dates

Frost dates for many Colorado communities may be found on the CMG website.


green line
green line

Authors: David Whiting with Carol O'Meara and Carl Wilson; Colorado State University Extension. Photographs and line drawings by David Whiting.

  • CMG GardenNotes are available online at www.cmg.colostate.edu
  • Colorado Master Gardener/Colorado Gardener Certificate Training is made possible by a grant from the Colorado Garden Show, Inc.
  • Colorado State University, U.S. Department of Agriculture, and Colorado counties cooperating
  • Extension programs are available to all without discrimination.
  • Colorado Master Gardener LogoNo endorsements of products mentioned is intended nor is criticism implied of products not mentioned.
  • Copyright. 2003-12. Colorado Master Gardener Program, Colorado State University Extension. All Rights Reserved. CMG GardenNotes may be reproduced without change or additions, for nonprofit educational use.

Revised January 2012

green line