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As a Colorado gardener, growing delicious squash is one of the prime joys of our short but bountiful growing season. But timing is everything when it comes to planting squash varieties that thrive in our state’s fickle mountain climate. Follow some key tips on squash planting times and techniques, and you’ll be rewarded with a plentiful yield of summer and winter squash.
An Overview of Popular Squash Varieties for Colorado
There are a few main types of squash commonly grown in Colorado gardens
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Summer squash – Includes zucchini, yellow straightneck, patty pan and crookneck squash. They have soft edible skins and fruits are harvested when immature and tender. Summer squash matures quickly in 50-65 days.
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Winter squash – Includes acorn, butternut, spaghetti and banana squash. These have hard inedible rinds and the mature fruits are harvested. They take 80-110 days to reach maturity.
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Pumpkins – Although technically a winter squash, pumpkins are often planted on their own schedule for fall decorating or giant pumpkin contests. Miniature pumpkins mature faster than large carving pumpkins.
Critical Factors for Determining Planting Time
Several key factors play a role in deciding the optimal time to safely direct seed or transplant squash in Colorado:
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Last spring frost date – This is the average date of the final frost in spring based on historical weather data for your location and hardiness zone.
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Soil temperature – Squash seeds germinate best when soil reaches at least 65-70°F. Soil warms up more slowly than air temperatures in spring.
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Elevation – Higher elevations above 5,000 feet have a shorter frost-free period. Squash may need started indoors.
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Days to maturity – Winter squash and pumpkins need adequate time to fully develop before autumn frost arrives.
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Growing season length – The longer the warm weather period before cold temperatures return, the better.
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Weather forecast – Short term temperature dips or heat waves predicted may adjust optimal planting dates.
Recommended Planting Dates for Squash Varieties
Here are some general guidelines for when to plant squash in different regions of Colorado:
Front Range (Zones 5-6)
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Summer squash – Mid to late May (after May 15th)
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Winter squash – Late May (after May 20th)
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Pumpkins – Early June (around June 1st)
Western Slope (Zones 5-7)
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Summer squash – Early to mid May (May 1st-15th)
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Winter squash – Mid May (around May 15th)
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Pumpkins – Late May (after May 20th)
Mountains (Zones 3-4)
- Start all squash 2-4 weeks earlier indoors, transplant after last frost
These dates may vary by 1-2 weeks depending on current soil temps and weather in your specific area.
How to Plant Squash in Colorado Gardens
Here are some key tips for getting squash planted at the optimal time:
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Direct sow summer squash seeds 1 inch deep, spaced 6-12 inches apart in rows or hills.
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Start winter squash and pumpkin seeds indoors 2-4 weeks before your target outdoor planting date.
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Harden off transplants for 7-10 days by slowly acclimating them to sun and outdoor conditions.
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Transplant winter squash and pumpkins when soil reaches 65°F, space 18-24 inches apart.
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Use cloches, row covers, or cold frames to protect tender seedlings if cold temperatures return.
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Use drip irrigation to maintain consistent moisture, especially for seeds and young plants.
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Mulch around plants to retain warmth and moisture in the soil.
Maximizing the Squash Growing Season
To get the most out of your squash crop and growing season, also consider these tips:
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Select early-maturing squash cultivars suited for your climate if available.
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Plant summer squash in succession every 2-3 weeks for a continuous harvest.
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Interplant fast-growing crops like radishes or lettuce between squash hills.
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Be prepared to cover or protect squash plants if hail or frost is predicted.
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Harvest summer varieties while young and tender, don’t allow to overmature.
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Allow winter varieties to fully mature on vine before harvesting for storage.
With proper timing, planting methods, and care you can enjoy a bountiful squash harvest in your Colorado garden. Consult local resources for optimal planting dates and squash varieties for your specific area and soil temperatures. Pay close attention to weather forecasts when making planting decisions. With the right approach, your squash will thrive this season!
Frequently Asked Questions About Planting Squash in Colorado
What’s the best way to warm up soil before planting squash?
Use plastic mulch, cloches, or row covers to trap heat. Also add compost and fertilizer to improve soil nutrition and microbial activity. Irrigating beds prior to planting also helps.
Should I direct seed or use transplants for squash?
Transplants extend the growing period so are recommended for pumpkins and winter squash. Either method works for quick-growing summer squash.
What soil temperature should I wait for before sowing seeds?
Wait until soil steadily reaches at least 65°F minimum, ideally 70°F. Check soil temp at the planting depth for accuracy.
Can I plant squash outside before my area’s last frost date?
No, squash is very frost tender. You can start seeds indoors 2-4 weeks before the average last spring frost for transplants.
How much space do squash plants need?
Provide at least 18-24 inches between plants, with 4-6 feet between rows for vining varieties.
Why are my squash plants flowering but not producing fruit?
Ensure both female and male flowers are present for pollination. Also protect from wind and maintain consistent soil moisture.
With the proper approach to timing, planting, and care, your Colorado squash will thrive this growing season. Monitor soil temperatures, choose suitable varieties, and use season extending techniques where helpful. Happy gardening!
For first-time gardeners or those new to Colorado, it’s helpful to understand a bit about our unique climate and growing conditions. Denver’s Climate & Elevation classifies as semi-arid high plain (Zone 6a). Although we receive 60 inches of snowfall per year in Denver, we only receive between 9-15 inches of precipitation usable for gardening.[/vc_column_text][/vc_column][/vc_row][vc_row type=”in_container” full_screen_row_position=”middle” column_margin=”default” column_direction=”default” column_direction_tablet=”default” column_direction_phone=”default” scene_position=”center” text_color=”dark” text_align=”left” row_border_radius=”none” row_border_radius_applies=”bg” overlay_strength=”0.3″ gradient_direction=”left_to_right” shape_divider_position=”bottom” bg_image_animation=”none”][vc_column column_padding=”no-extra-padding” column_padding_tablet=”inherit” column_padding_phone=”inherit” column_padding_position=”all” background_color_opacity=”1″ background_hover_color_opacity=”1″ column_shadow=”none” column_border_radius=”none” column_link_target=”_self” gradient_direction=”left_to_right” overlay_strength=”0.3″ width=”1/2″ tablet_width_inherit=”default” tablet_text_alignment=”default” phone_text_alignment=”default” column_border_width=”none” column_border_style=”solid” bg_image_animation=”none”][vc_column_text]
The average last frost in Denver is mid-May and the average first frost is mid-October. This determines the best times to sow seeds indoors or outdoors, depending on the crop and their preferred soil and air temperatures. It also guides us as to when to plant warm weather crops outside to avoid transplant shock and stunting due to temperature fluctuations and unexpected late-season snow.
Planting and Harvesting Tips[/vc_column_text][/vc_column][/vc_row][vc_row type=”in_container” full_screen_row_position=”middle” column_margin=”default” column_direction=”default” column_direction_tablet=”default” column_direction_phone=”default” scene_position=”center” text_color=”dark” text_align=”left” row_border_radius=”none” row_border_radius_applies=”bg” overlay_strength=”0.3″ gradient_direction=”left_to_right” shape_divider_position=”bottom” bg_image_animation=”none”][vc_column column_padding=”no-extra-padding” column_padding_tablet=”inherit” column_padding_phone=”inherit” column_padding_position=”all” background_color_opacity=”1″ background_hover_color_opacity=”1″ column_shadow=”none” column_border_radius=”none” column_link_target=”_self” gradient_direction=”left_to_right” overlay_strength=”0.3″ width=”1/2″ tablet_width_inherit=”default” tablet_text_alignment=”default” phone_text_alignment=”default” column_border_width=”none” column_border_style=”solid” bg_image_animation=”none”][vc_column_text]
Pole Beans: Sensitive to transplanting; pinch extra plants, don’t pull them. Pick every 3-7 days.
Beets: Thin when young and cook the tops as you would with other greens.
Broccoli: Keep cool to get stocky plants, but don’t go below 40° F. Transplant into beds up to first true leaves. Harvest the main head when buds begin to loosen. Side heads will form after the first head is cut.
Brussel Sprouts: Keep cool to get stocky plants, but don’t go below 40° F. Harvest sprouts when they are 1 ½” wide. Pick lower ones first.
Cabbage: Harvest when head is formed. Keep cool to get stocky but don’t go below 40° F.
Carrots: Thin early; harvest any size.
Chard: Cut leaves close to ground when 8-10” high. Harvest outer leaves first.
Corn: Sensitive to transplanting. Pinch extra plants. Plant in blocks; harvest when kernels are milky.
Cucumber: Somewhat sensitive to transplanting; pinch extra plants. Mound soil into hills; plant 3 seeds per hill.
Eggplant: Grows well in hot weather.
Garlic: Harvest when tops start to die.
Kale: Keep cool to get stocky plants, but not below 40° F. Cut outer leaves closer to the stem when 10” or longer.
Kohlrabi: Keep cool to get stocky plants, but not below 40° F. Harvest when the bulb is 3” in diameter.
Leeks: Keep cool to get stocky plants, but not below 40° F. Plant out when 4” high.
Parsley: Soak seeds overnight to speed germination. Cut outer leaves near the stem.
Peas: Sensitive to transplanting, pinch extra plants, don’t pull them. Harvest frequently.
Peppers: Sensitive to cold, harden off gradually. Green peppers turn red when ripe.
Potatoes: Very tender; cannot tolerate frost. Dig up with a digging fork after the tops have flowered.
Pumpkin: Sensitive to transplanting; Pinch, don’t pull plants. Plant in hills, 3-4 plants per hill, 6-8 ft. apart.
Radish: Plant every 10 days. Will get woody when over mature.
Spinach: Keep cool for stocky plants. Plant every 2 weeks. Will go to seed in hot weather.
Squash, Summer: Sensitive to transplanting; pinch extra plants, don’t pull them. Harvest frequently.
Squash, Winter: Sensitive to transplanting; pinch extra plants, don’t pull. Can store through the winter.