Colorado gardeners face unpredictable spring frosts, making cold-hardy selections like peas and spinach the smartest March choices. When you are searching for the best vegetables to plant in march in colorado, you need to focus on crops that can handle sudden temperature drops and even a late snow. March in Colorado is a month of transition, where the soil might still be frozen in some areas but workable in others. This guide walks you through exactly what to put in the ground now for a strong harvest later.
You do not need to wait until May to start gardening. Many vegetables thrive when planted in March, as long as you choose the right varieties and protect them from frost. The key is understanding your local microclimate and using simple season-extending techniques like row covers or cold frames. Let’s get into the specifics so you can make the most of your early spring garden.
Best Vegetables To Plant In March In Colorado
This section covers the top cold-hardy vegetables that perform well in Colorado’s March conditions. These crops can germinate in cool soil and tolerate light freezes, giving you a head start on the growing season. Each vegetable has specific planting depths and spacing requirements that work best for our state’s unique climate.
Peas
Peas are arguably the most reliable March planting for Colorado. They germinate in soil temperatures as low as 40°F and can survive frost without damage. Plant them as soon as the ground is workable, which is usually mid to late March in most areas.
- Plant seeds 1 inch deep and 2 inches apart
- Use a trellis or netting for support
- Choose shelling peas, snow peas, or snap peas
- Water sparingly until sprouts appear
Spinach
Spinach loves cool weather and actually bolts when temperatures rise above 80°F. March planting gives you a full harvest before summer heat arrives. It is one of the fastest-growing greens you can start now.
- Sow seeds 1/2 inch deep and 2 inches apart
- Thin seedlings to 4 inches apart once they grow
- Harvest outer leaves first for continuous growth
- Cover with row cover if a hard freeze is forecast
Lettuce
Lettuce varieties like romaine, butterhead, and leaf lettuce do well in March. They germinate best when soil temperatures are between 45°F and 65°F. You can direct sow seeds or start transplants indoors for an even earlier harvest.
- Plant seeds 1/4 inch deep
- Space rows 12 inches apart
- Keep soil consistently moist but not waterlogged
- Use shade cloth later in spring to prevent bitterness
Kale
Kale is extremely cold-hardy and can survive temperatures down to 20°F once established. March planting allows you to harvest tender leaves well into June. It also tolerates Colorado’s dry air better than some other greens.
- Sow seeds 1/2 inch deep and 12 inches apart
- Thin to 18 inches apart for larger plants
- Harvest from the bottom up
- Mulch around plants to retain moisture
Carrots
Carrots need loose, rock-free soil to grow straight. March is ideal for planting because the cool soil encourages sweet, crisp roots. They take 60 to 80 days to mature, so you will harvest in late spring.
- Plant seeds 1/4 inch deep and 1 inch apart
- Thin to 3 inches apart after germination
- Keep soil moist for even germination
- Choose short varieties like ‘Nantes’ for heavy clay soil
Radishes
Radishes are the fastest crop you can plant in March. Some varieties mature in just 25 days. They are perfect for marking rows of slower-growing vegetables like carrots or parsnips.
- Sow seeds 1/2 inch deep and 1 inch apart
- Thin to 2 inches apart for larger roots
- Water regularly to prevent woody texture
- Plant successive crops every two weeks
Beets
Beets tolerate light frost and grow well in Colorado’s alkaline soil. Both the roots and greens are edible. March planting gives you a head start on summer harvests.
- Plant seeds 1 inch deep and 2 inches apart
- Soak seeds overnight for better germination
- Thin to 4 inches apart
- Harvest when roots are 1 to 2 inches in diameter
Onions
Onions can be planted as sets or seeds in March. Sets are easier for beginners and establish quickly. They tolerate cold well and will start growing as soon as the soil warms slightly.
- Plant sets 1 inch deep and 4 inches apart
- Space rows 12 inches apart
- Water deeply but infrequently
- Harvest when tops fall over and turn brown
Swiss Chard
Swiss chard is a colorful, heat-tolerant green that starts well in March. It can handle light frost and produces leaves for months. It is also more forgiving of poor soil than spinach.
- Sow seeds 1 inch deep and 6 inches apart
- Thin to 12 inches apart
- Harvest outer leaves when 6 inches tall
- Mulch to keep roots cool in summer
Turnips
Turnips are dual-purpose crops: you can eat the roots and the greens. They grow quickly in cool weather and are ready in 40 to 60 days. March planting ensures a harvest before summer heat turns them woody.
- Plant seeds 1/2 inch deep and 2 inches apart
- Thin to 4 inches apart for roots
- Water consistently for tender roots
- Harvest when roots are 2 to 3 inches wide
Preparing Your Colorado Garden Soil In March
Before you plant anything, you need to prepare the soil properly. Colorado soil is often heavy clay or sandy, with low organic matter. March is the perfect time to amend it because the ground is thawing and workable.
Test Your Soil First
Get a soil test from your local extension office. This tells you pH levels and nutrient deficiencies. Most Colorado soil is alkaline, with a pH above 7.0. Vegetables like peas and spinach prefer slightly acidic to neutral soil, so you may need to add sulfur or compost.
- Collect samples from different areas of your garden
- Mix samples together for a composite test
- Follow recommendations for lime or sulfur application
Add Organic Matter
Compost is your best friend in Colorado gardening. It improves drainage in clay soil and water retention in sandy soil. Spread 2 to 3 inches of compost over your beds and work it into the top 6 inches.
- Use well-rotted compost, not fresh manure
- Avoid peat moss, which dries out quickly in our climate
- Consider worm castings for added nutrients
Consider Raised Beds
Raised beds warm up faster in spring and drain better than ground soil. They are ideal for March planting because you can work the soil earlier. Build beds at least 8 inches deep for root vegetables.
- Use untreated wood, stone, or metal
- Fill with a mix of compost, topsoil, and perlite
- Install drip irrigation for consistent moisture
Frost Protection Strategies For March Plantings
Colorado’s last frost date varies widely, from late April in Denver to late May in the mountains. Even after planting, you need to be ready for sudden cold snaps. These strategies keep your vegetables safe.
Row Covers
Floating row covers are lightweight fabrics that protect plants from frost while letting light and water through. They can add 2 to 4 degrees of frost protection. Use them on nights when temperatures drop below 28°F.
- Drape covers directly over plants or use hoops
- Secure edges with soil or bricks
- Remove covers during the day if temperatures rise above 60°F
Cold Frames
Cold frames are like mini greenhouses that trap heat from the sun. They are perfect for hardening off seedlings or starting crops extra early. You can buy them or build one from old windows.
- Place cold frames facing south for maximum sunlight
- Ventilate on warm days to prevent overheating
- Use them for lettuce, spinach, and kale
Cloches
Cloches are individual plant covers made from plastic or glass. They work well for protecting a few plants. Use them for tender seedlings or newly transplanted vegetables.
- Use milk jugs with bottoms cut off as DIY cloches
- Remove during the day to prevent heat buildup
- Anchor cloches with rocks or stakes
Watering Tips For March Gardens In Colorado
March in Colorado is typically dry, with low humidity and occasional wind. Your March plantings need consistent moisture to germinate and establish. Overwatering is less of a risk than underwatering at this time of year.
Check Soil Moisture Daily
Stick your finger 1 inch into the soil. If it feels dry, it is time to water. Newly planted seeds need moist soil to germinate, but not soggy conditions that cause rot.
- Water in the morning to reduce evaporation
- Use a gentle spray to avoid washing away seeds
- Mulch around plants to retain moisture
Use Drip Irrigation
Drip irrigation delivers water directly to the root zone, reducing waste and preventing fungal diseases. It is especially useful for rows of peas, carrots, and onions.
- Install drip lines before planting
- Set a timer for consistent watering
- Check emitters regularly for clogs
Common Mistakes To Avoid When Planting In March
Even experienced Colorado gardeners make mistakes in March. Avoid these pitfalls to ensure a successful early garden.
Planting Too Early
If the soil is still frozen or waterlogged, wait. Planting in mud compacts the soil and rots seeds. Test by squeezing a handful of soil: it should crumble, not form a ball.
- Wait until soil temperature reaches at least 40°F
- Use a soil thermometer for accuracy
- Start seeds indoors if ground is not ready
Ignoring Microclimates
Your garden may have warmer or cooler spots. South-facing slopes warm up faster, while low areas collect cold air. Plant tender crops in the warmest spots and hardy ones in cooler areas.
- Observe where snow melts first in your yard
- Plant near walls or fences for extra warmth
- Avoid planting in frost pockets
Overwatering
Cool soil holds moisture longer than warm soil. Overwatering in March can lead to damping off disease, which kills seedlings. Water only when the top inch of soil is dry.
- Use a moisture meter for precision
- Reduce watering during rainy periods
- Improve drainage with organic matter
Succession Planting For Continuous Harvests
March is just the beginning. To get the most from your garden, plan for succession planting. This means planting new crops every few weeks to replace harvested ones.
What To Plant After March Crops
Once you harvest your March-planted peas, spinach, or radishes, replant with warm-season vegetables like beans, tomatoes, or peppers. This keeps your garden productive all season.
- Plant bush beans after peas are done
- Follow radishes with cucumber or squash
- Replace lettuce with basil or peppers
Staggered Planting Dates
Instead of planting all your carrots at once, plant a row every two weeks. This gives you a steady supply rather than a glut. It works well for radishes, lettuce, and beets.
- Mark planting dates on a calendar
- Use different varieties for different harvest times
- Keep extra seeds on hand for replanting
Frequently Asked Questions
Can I Plant Tomatoes In March In Colorado?
No, tomatoes are warm-season crops and cannot tolerate frost. Wait until after the last frost date, usually mid to late May, to transplant tomatoes. Start seeds indoors in March instead.
What Vegetables Can I Plant In March In Colorado For Fall Harvest?
For a fall harvest, plant cool-season crops like kale, Brussels sprouts, and cabbage in late March. They will grow through spring and summer, then produce again in cooler weather.
How Deep Should I Plant Seeds In March In Colorado?
Most seeds should be planted at a depth of two to three times their diameter. Small seeds like lettuce and carrots need only 1/4 inch, while larger seeds like peas and beans need 1 inch.
Should I Use Fertilizer When Planting In March?
Yes, but use a balanced, slow-release fertilizer. Avoid high-nitrogen fertilizers that promote leafy growth at the expense of roots. Compost is usually sufficient for most vegetables.
Can I Grow Broccoli In March In Colorado?
Yes, broccoli is cold-hardy and can be planted in March. Start seeds indoors 6 weeks before transplanting, or direct sow in late March for a summer harvest. It prefers consistent moisture.
March gardening in Colorado requires patience and preparation, but the rewards are worth it. By choosing the best vegetables to plant in march in colorado—like peas, spinach, kale, and carrots—you set yourself up for a productive season. Use frost protection, prepare your soil well, and water wisely. Your early efforts will pay off with fresh, homegrown vegetables weeks before your neighbors even start planting. Get out there and enjoy the crisp spring air while you work the soil. Your garden will thank you.