What to Plant in September: 5 Must-Grow Vegetables for Fall

Cool-Season Leafy Greens

September marks the perfect transition into fall gardening, offering ideal conditions for planting a variety of vegetables that thrive in cooler temperatures. As summer's intense heat begins to fade, your garden soil retains warmth while the air cools, creating optimal growing conditions for many crops. If you're wondering WHAT TO PLANT in September, leafy greens should top your list for their quick growth and nutritional benefits.

Kale and Spinach Varieties

Kale and spinach represent the champions of fall gardening, offering incredible versatility and nutritional value. These leafy powerhouses actually develop sweeter flavors when exposed to light frosts, making them perfect candidates for your September planting schedule.

For kale enthusiasts, consider these excellent varieties:

• Lacinato (Dinosaur) kale, with its deep blue-green leaves and sweet flavor

• Red Russian kale, featuring tender purple-veined foliage

• Curly kale, the classic ruffled variety that holds up well to frost

Spinach varieties particularly suited for fall planting include:

• Bloomsdale, an heirloom variety known for its crinkled texture and cold hardiness

• Space, which offers smooth leaves and quick maturity

• Winter Giant, specifically bred for cool-season growing

Both kale and spinach can be harvested multiple times through fall and, in milder climates, even into winter. Simply pick the outer leaves while leaving the growing center intact for continuous production.

Planting and Care Tips

When considering WHAT TO PLANT in September, proper planting techniques for leafy greens ensure success. Start by selecting a location that receives at least 4-6 hours of sunlight daily. While summer vegetables demand full sun, fall greens can tolerate partial shade, which may actually benefit them as the season progresses.

Prepare your soil by:

1. Removing any summer crop debris

2. Working in 2-3 inches of compost to replenish nutrients

3. Ensuring good drainage to prevent root rot during fall rains

For direct seeding:

• Plant kale seeds ¼ to ½ inch deep

• Space spinach seeds about 2 inches apart in rows

• Keep soil consistently moist until germination occurs

For transplants:

• Space kale plants 12-18 inches apart

• Position spinach seedlings 6-8 inches apart

• Water thoroughly after planting

Both crops benefit from a layer of mulch to maintain soil moisture and suppress weeds. As temperatures drop, consider adding row covers to extend your harvest season even further. With minimal protection, these leafy greens can provide nutritious harvests well into the cooler months.

Root Vegetables for Fall

Root vegetables truly shine in fall gardens, developing sweeter flavors as temperatures cool. September provides the perfect window for planting these underground treasures that store well and provide hearty nutrition throughout the colder months.

Radishes and Turnips

When deciding WHAT TO PLANT in September, radishes deserve special consideration for their remarkably quick growth cycle. From seed to harvest in just 21-30 days, they provide nearly instant gratification for fall gardeners. Turnips, while taking slightly longer at 40-60 days, offer the dual benefit of edible roots and nutritious greens.

For fall radish planting, consider these varieties:

• Cherry Belle, the classic round red radish that matures in about 22 days

• Watermelon radish, featuring green skin and stunning pink interior

• Daikon, the long white Asian variety excellent for storage

Recommended turnip varieties for September planting include:

• Purple Top White Globe, the traditional favorite with purple shoulders

• Tokyo Cross, prized for tender roots even at larger sizes

• Golden Ball, with sweet yellow flesh that's less spicy than white varieties

Planting techniques for both vegetables remain straightforward. Sow seeds directly in prepared soil about ½ inch deep and 1 inch apart. Once seedlings emerge, thin radishes to 2 inches apart and turnips to 4-6 inches for proper root development. Harvest radishes as soon as they reach edible size to prevent them from becoming pithy or splitting.

Soil Preparation Essentials

Root vegetables demand specific soil conditions to develop properly. Unlike leafy greens that can tolerate heavier soils, radishes and turnips require loose, well-draining soil to form straight, unblemished roots. September provides an ideal time to improve your soil structure before planting.

To prepare optimal growing conditions:

1. Loosen soil to a depth of 10-12 inches, removing rocks and breaking up clumps

2. Incorporate aged compost but avoid fresh manure, which can cause forking

3. Consider adding sand to heavy clay soils to improve drainage

4. Maintain soil pH between 6.0-7.0 for best nutrient availability

Common mistakes to avoid include:

• Over-fertilizing with nitrogen, which produces lush tops but poor root development

• Inconsistent watering, which can cause splitting or bitter flavors

• Planting too densely, preventing proper root formation

For container gardeners, select pots at least 8 inches deep for radishes and 12 inches for turnips. Use a quality potting mix amended with compost rather than garden soil, which can compact in containers. Regular, gentle watering keeps roots growing steadily without stress, resulting in tender, flavorful harvests.

Brassica Family Stars

The brassica family, also known as cruciferous vegetables, contains some of the most nutritious and versatile fall crops. September offers the perfect timing for planting these garden favorites, allowing them enough time to mature before severe winter weather arrives.

Broccoli and Cauliflower

When planning WHAT TO PLANT in September, broccoli and cauliflower deserve prime consideration. These nutritional powerhouses thrive in the cooling temperatures of fall, often producing better results than spring plantings in many regions.

For successful fall broccoli, consider these varieties:

• Calabrese, an heirloom variety that produces a large central head followed by numerous side shoots

• Belstar, known for its heat tolerance during early fall warm spells

• Waltham 29, specifically developed for fall harvests with excellent cold tolerance

Recommended cauliflower varieties for September planting include:

• Snow Crown, a reliable performer that matures quickly (50-60 days)

• Amazing, with self-wrapping leaves that protect the white curds

• Graffiti, a stunning purple variety rich in antioxidants

For best results, start with transplants rather than seeds unless you're in a very mild climate. Plant seedlings 18-24 inches apart in rows spaced 24-36 inches apart. Water deeply at planting time and apply a balanced organic fertilizer according to package directions.

A key technique for cauliflower is blanching, which protects the developing heads from sunlight to maintain their white color. When heads reach about 2-3 inches in diameter, gently fold the outer leaves over the curd and secure with twine or a clothespin.

Protection from Early Frosts

While brassicas generally tolerate light frosts, sudden temperature drops can damage young plants. Established broccoli and cauliflower can actually benefit from light frosts, which enhance flavor by converting starches to sugars, but protection methods ensure consistent growth through unpredictable fall weather.

Effective frost protection strategies include:

1. Applying 2-3 inches of mulch around plants to insulate soil and roots

2. Installing floating row covers when temperatures threaten to drop below 28°F

3. Creating temporary hoop houses using plastic sheeting over bent PVC pipes

4. Monitoring weather forecasts to anticipate protection needs

Watch for common fall pests like cabbage worms and aphids, which can still be active in September. Inspect plants regularly and treat with organic methods such as neem oil or insecticidal soap at the first sign of infestation.

With proper care and protection, these brassica family stars can provide nutritious harvests well into late fall or early winter, depending on your climate zone. The effort invested in protecting these plants pays dividends in fresh, homegrown vegetables when most summer crops have long finished producing.

Garlic and Onion Sets

Fall presents the ideal time to plant certain crops that require a period of cold weather to develop properly. Garlic and onion sets planted in September will establish roots before winter dormancy, then burst into vigorous growth when spring arrives.

Planting for Spring Harvest

When considering WHAT TO PLANT in September for long-term planning, garlic and certain onion varieties offer exceptional value. These plants require minimal maintenance while delivering impressive yields months later.

For garlic planting success:

• Choose between hardneck varieties (which produce edible scapes and larger cloves) or softneck types (better for braiding and longer storage)

• Popular hardneck varieties include Music, German Red, and Chesnok Red

• Reliable softneck options include Inchelium Red, California Early, and Nootka Rose

For fall-planted onions:

• Select "long-day" varieties if you're in northern regions or "short-day" types for southern areas

• Yellow varieties like Stuttgarter and White Ebenezer perform particularly well when fall-planted

• Egyptian walking onions offer a perennial option that produces both underground bulbs and topsets

The planting process for garlic involves separating bulbs into individual cloves while keeping the papery skin intact. Plant cloves pointed-end up, 2 inches deep and 6 inches apart. For onion sets, plant the small bulbs 1 inch deep and 4-6 inches apart, with just the tips showing above soil level.

Both crops benefit from a generous layer of mulch applied after planting. This insulates the soil through winter temperature fluctuations and suppresses spring weeds that might compete with your developing plants.

Spacing and Mulching

Proper spacing and mulching techniques significantly impact the size and quality of your garlic and onion harvests. These crops need room to develop fully underground while competing effectively with neighboring plants for nutrients.

For optimal development:

1. Space garlic cloves 6-8 inches apart in rows 12 inches apart

2. Position onion sets 4-6 inches apart in rows 12-18 inches apart

3. Plant in blocks rather than single rows to maximize space efficiency

4. Ensure planting areas receive at least 6 hours of direct sunlight daily

After planting, apply a 3-4 inch layer of mulch using:

• Straw (avoid hay, which contains seeds)

• Shredded leaves

• Aged pine needles

• Compost

This substantial mulch layer serves multiple purposes:

• Prevents soil heaving during freeze-thaw cycles

• Retains soil moisture during dry periods

• Gradually breaks down to feed soil organisms

• Suppresses spring weed competition

While garlic and onions require minimal care through winter, remove some mulch in early spring to allow soil to warm more quickly. Side-dress with a nitrogen-rich fertilizer when active growth resumes to support leaf development, which directly correlates to bulb size at harvest.

Hardy Herbs for Flavor

September offers an excellent opportunity to establish perennial herbs and cold-tolerant annual varieties that will enhance your cooking throughout fall and winter. Many herbs actually develop more concentrated flavors when grown in cooler temperatures.

Cilantro and Parsley

When deciding WHAT TO PLANT in September, cilantro and parsley stand out as particularly well-suited herbs for fall gardens. Unlike their tendency to bolt quickly in summer heat, these herbs thrive in autumn's cooler temperatures, remaining productive for months.

Cilantro planted in September offers:

• Prolonged harvest period without premature flowering

• Sweeter, more complex flavor than summer-grown plants

• Ability to withstand light frosts with minimal protection

• Self-seeding potential for next season's volunteers

Parsley varieties for fall planting include:

• Flat-leaf (Italian) parsley, prized for superior flavor in cooking

• Curly parsley, excellent for garnishes and cold hardiness

• Hamburg parsley, grown for its edible root and foliage

Both herbs grow easily from seed sown directly in the garden. Plant seeds ¼ inch deep in prepared soil, keeping the area consistently moist until germination. Thin seedlings to 6-8 inches apart for proper air circulation. Harvest outer leaves regularly to encourage continued production, taking no more than one-third of the plant at once.

For extended harvests in colder regions, consider planting these herbs near a south-facing wall that radiates heat or in protected areas of the garden. A light covering of row fabric during hard freezes can extend your harvest significantly.

Container Growing Options

Container cultivation offers particular advantages for fall herb growing, allowing gardeners to move plants to protected locations during severe weather while maximizing limited space. September-planted herbs in containers can thrive on patios, balconies, or even indoor windowsills as temperatures drop.

For successful container herb gardens:

1. Select pots at least 8-10 inches deep with adequate drainage holes

2. Use high-quality potting mix amended with compost rather than garden soil

3. Position containers where they receive 4-6 hours of sunlight daily

4. Group containers for easier protection during cold snaps

Ideal container combinations include:

• Cilantro paired with cool-season flowers like pansies or violas

• Parsley planted with other Mediterranean herbs like thyme and sage

• Mixed herb containers featuring varying heights and textures

Water container herbs more judiciously in fall than summer, allowing the soil surface to dry slightly between waterings. However, never let containers dry completely, as herbs recover poorly from drought stress in cooler weather.

As temperatures drop below freezing regularly, consider moving containers to a sheltered location such as:

• Against a house wall

• Under eaves or overhangs

• Into an unheated garage during extreme cold

• Near a south-facing window indoors

With minimal protection, container-grown cilantro and parsley can provide fresh flavors throughout fall and often into winter, offering a welcome taste of garden freshness when outdoor growing has largely ceased.

Extending Your Growing Season

September planting opens opportunities to enjoy homegrown produce well beyond traditional harvest seasons. With thoughtful planning and simple protection methods, your fall garden can remain productive even as temperatures drop and daylight hours shorten.

When considering WHAT TO PLANT in September, remember that timing is crucial. Calculate your first expected frost date and select varieties with "days to maturity" that allow harvest before severe weather arrives. Many seed packets specifically indicate varieties suitable for fall planting, taking advantage of these recommendations increases your chances of success.

The key to extending your growing season includes:

1. Utilizing microclimates within your garden, such as south-facing walls that retain heat

2. Applying season extension tools like row covers, cold frames, or mini hoop tunnels

3. Mulching heavily to insulate soil and protect roots from temperature fluctuations

4. Selecting cold-hardy varieties specifically bred for fall and winter production

Many vegetables actually develop sweeter flavors after light frosts convert starches to sugars, making your fall harvest potentially more flavorful than summer crops. With minimal investment in simple protection methods, you can continue harvesting fresh produce weeks or even months beyond your region's first frost date.

Remember that fall gardens typically require less maintenance than summer plots, with fewer pest pressures and reduced watering needs. This makes September planting particularly rewarding for busy gardeners seeking maximum returns from minimal effort. Your fall garden can be just as productive as summer with these carefully selected varieties that thrive in cooling temperatures.

As you plan WHAT TO PLANT in September, consider your specific growing conditions, available space, and culinary preferences. Whether you're working with a spacious backyard plot or a few containers on a patio, these fall vegetables and herbs can provide abundant harvests and the satisfaction of growing your own food well into the cooler months.