Our unique climate and altitude in the San Luis Valley can present challenges to local gardeners. But, believe it or not, there's a lot of opportunities as well! As summer winds down and hints of autumn appear, September offers a final chance to plant crops that will thrive in cooler temperatures. With thoughtful planning and a focus on cool-season varieties, you can extend your harvest well into the fall. This guide will walk you through what to plant in September in the San Luis Valley for a bountiful fall garden.
Understanding the San Luis Valley Climate
With an average altitude of 7,500 feet, our region experiences a short growing season that typically ranges from late May to early September. However, September is often a month of transition, with temperatures dropping and the first frosts occurring as early as mid-September. This makes it essential to choose crops that can withstand or even thrive in cooler conditions.
Cool-Season Vegetables to Plant in September
September is the perfect time to plant cool-season vegetables that prefer the milder temperatures of fall. Here are some top choices for the San Luis Valley:
- Leafy Greens: Spinach, kale, and Swiss chard are excellent choices for fall planting. These greens are frost-tolerant and can continue producing well into the cooler months. Sow seeds directly into the soil in early September for the best results.
- Root Vegetables: Carrots, beets, and radishes are ideal for fall. These vegetables prefer cooler weather and can be harvested before the ground freezes. Beets and carrots can be sown in early September, while radishes, with their short growing period, can be planted throughout the month.
- Brassicas: Broccoli, cauliflower, and Brussels sprouts are perfect for fall planting. These hardy vegetables can withstand frosty nights and often develop better flavor when grown in cooler weather. Transplants are recommended for these crops, as starting from seed in September may not allow enough time for maturity.
- Garlic: Although typically planted in late September to October, garlic is a must for any fall garden. Plant cloves in well-drained soil, about 2 inches deep and 6 inches apart. Garlic will establish roots in the fall and be ready for harvest the following summer.
Flowers for a Fall Garden
In addition to vegetables, consider adding some cool-season flowers to your garden. These flowers not only provide color but can also attract beneficial insects and pollinators to your garden.
- Pansies and Violas: These cold-hardy flowers can withstand light frosts and will add vibrant color to your garden through the fall. Plant them in September, and with a bit of protection, they may even survive into early winter.
- Calendula: Also known as pot marigold, calendula is a hardy annual that can be sown directly into the garden in September. It will bloom through the fall, adding a splash of orange and yellow to your landscape.
- Snapdragons: These tall, spiky flowers are perfect for adding height and interest to your fall garden. Snapdragons are frost-tolerant and can continue blooming until the first hard freeze.
Cover Crops for Soil Health
Cover crops, also known as green manure, are an essential part of sustainable gardening. They improve soil structure, add nutrients, and help prevent erosion. In the San Luis Valley, where the growing season is short, planting cover crops in September can prepare your garden for the next season.
- Winter Rye: One of the best cover crops for colder climates, winter rye is hardy and can survive the harshest of winters. Plant it in September to protect and enrich your soil through the winter. It will establish roots before winter sets in and resume growth in early spring.
- Hairy Vetch: This legume is an excellent nitrogen fixer and works well when mixed with winter rye. It adds valuable organic matter to the soil and provides a green blanket that suppresses weeds.
- Crimson Clover: Although slightly less cold-hardy than winter rye, crimson clover is still a good choice for the San Luis Valley. It adds nitrogen to the soil and can be used as a ground cover to prevent erosion.
Tips for Extending the Growing Season
Given the early frosts in the San Luis Valley, extending the growing season is crucial for maximizing your fall harvest. Here are some tips to help you do just that:
- Use Row Covers: Lightweight row covers can protect your crops from light frosts while allowing sunlight and moisture to reach the plants. They are particularly useful for leafy greens and brassicas.
- Mulch Heavily: Applying a thick layer of mulch around your plants helps retain soil moisture and keeps the ground warmer. Straw, leaves, or even compost can be used as mulch.
- Cold Frames: Constructing a cold frame is an effective way to extend the growing season. These mini-greenhouses trap heat and protect plants from frost, allowing you to grow vegetables well into the fall.
- Plant in Microclimates: Take advantage of microclimates in your garden, such as south-facing slopes or areas near buildings that retain heat. These spots can provide a few extra degrees of warmth, which can make a big difference in the fall.
Conclusion
With its unique climate, the San Luis Valley requires a thoughtful approach to gardening, especially in the fall. By selecting the right cool-season vegetables, flowers, and cover crops, you can enjoy a productive and colorful garden even as the days shorten and temperatures drop. With proper planning and a few season-extending techniques, your fall garden can be a bountiful success, providing fresh produce and vibrant blooms well into the cooler months.
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