Oklahoma’s September heat gradually gives way to cooler nights, creating prime conditions for certain fall vegetables. If you are looking for the best vegetables to plant in september in oklahoma, you have come to the right place. September is a transition month here, and with a little planning, you can enjoy a bountiful harvest well into November or even December.
This guide covers exactly what to plant, when to plant it, and how to care for your fall garden. We will focus on crops that thrive in Oklahoma’s unique climate—hot days, cool nights, and the occasional early frost. Let’s get started.
Best Vegetables To Plant In September In Oklahoma
September planting in Oklahoma is all about cool-season crops. These vegetables love the milder temperatures and can handle a light frost. Here are the top choices, broken down by category for easy planning.
Leafy Greens For Quick Harvests
Leafy greens are the stars of the fall garden. They grow fast, tolerate cool weather, and can be harvested multiple times. Plant them in early September for the best results.
- Spinach: Sow seeds directly in the ground. Spinach loves cool soil and will germinate quickly. Harvest outer leaves when they are 3-4 inches tall.
- Lettuce: Choose loose-leaf varieties like Black Seeded Simpson or Red Romaine. They mature in 45-50 days. Plant in partial shade if the September sun is still intense.
- Kale: This is a powerhouse for Oklahoma fall gardens. Kale gets sweeter after a frost. Plant transplants or seeds in early September.
- Swiss Chard: Very heat tolerant for a leafy green. It will keep producing until a hard freeze. Harvest the outer stems and leaves.
- Arugula: Spicy and fast. You can start harvesting in as little as 20 days. Plant in succession every two weeks for a continuous supply.
Root Vegetables That Store Well
Root crops are perfect for September planting because they develop underground, where the soil stays warm longer. They also store well for winter use.
- Carrots: Sow seeds directly ½ inch deep. Keep the soil moist until they germinate. Varieties like Danvers or Nantes do well in Oklahoma’s clay soil if you loosen it first.
- Beets: Plant seeds 1 inch apart. Both the roots and greens are edible. Harvest when roots are 1-2 inches across.
- Radishes: The fastest root crop. Some varieties mature in 25 days. Plant a small patch every week for a steady harvest.
- Turnips: Great for both roots and greens. Plant in early September for a fall harvest. They tolerate light frosts well.
- Parsnips: These need a long growing season but are worth it. Plant in early September and harvest after a frost for sweeter flavor.
Brassicas For Hearty Fall Meals
Brassicas, or cole crops, are cool-weather champions. They can handle temperatures down to 20°F once established. Start with transplants for a head start.
- Broccoli: Set out transplants in early September. Harvest the main head before it flowers, then side shoots will form.
- Cauliflower: Needs consistent moisture and cool temps. Plant transplants and blanch the heads by tying leaves over them.
- Cabbage: Choose early-maturing varieties like Early Jersey Wakefield. Space plants 12-18 inches apart.
- Brussels Sprouts: These take 90-100 days but are perfect for Oklahoma. They taste best after a frost. Plant transplants in early September.
- Collards: Very heat tolerant for a brassica. They keep producing through light frosts. Harvest lower leaves first.
Alliums For Flavor
Onions and garlic are typically planted in fall for a spring harvest, but you can also plant green onions for quick use.
- Green Onions: Plant sets or seeds in September. Harvest when the stems are pencil-thick. They are ready in 60-70 days.
- Garlic: Plant individual cloves in late September or October. They will overwinter and produce bulbs next summer.
- Shallots: Similar to garlic, plant in fall for a summer harvest. They are more cold-hardy than onions.
Step-By-Step Planting Guide For September
Follow these steps to ensure your September garden succeeds. Oklahoma’s weather can be unpredictable, so timing and preparation matter.
Prepare Your Soil
Good soil is the foundation of a productive garden. Start by testing your soil pH. Most vegetables prefer a pH between 6.0 and 7.0.
- Remove any summer crop debris. This prevents disease carryover.
- Add 2-3 inches of compost or well-rotted manure. Work it into the top 6 inches of soil.
- If your soil is heavy clay, add sand or perlite to improve drainage. Carrots and beets need loose soil.
- Apply a balanced fertilizer like 10-10-10 at the rate recommended on the package.
- Rake the bed smooth and water it thoroughly a day before planting.
Timing Your Planting
In Oklahoma, the first frost usually occurs between October 15 and November 15, depending on your zone. Use the “days to maturity” on seed packets to count backward from your expected first frost.
- Early September: Plant spinach, lettuce, kale, radishes, and turnips. These mature in 30-60 days.
- Mid-September: Plant carrots, beets, broccoli transplants, and cabbage. They need 60-80 days.
- Late September: Plant garlic and shallots. They overwinter and grow in spring.
- Any time: Plant arugula and green onions. They are fast and forgiving.
Watering Wisely
September in Oklahoma can still be hot. Water deeply and less frequently to encourage deep root growth. Aim for 1 inch of water per week, including rainfall.
- Water in the morning to reduce evaporation and prevent fungal diseases.
- Use drip irrigation or soaker hoses to keep foliage dry.
- Check soil moisture by sticking your finger 2 inches into the soil. If it feels dry, water.
- Mulch around plants with straw or shredded leaves to retain moisture and regulate soil temperature.
Protecting From Pests
Fall gardens have fewer pests than summer gardens, but some still linger. Aphids, cabbage worms, and slugs can be problems.
- Use row covers to protect young plants from insects. They also add a few degrees of frost protection.
- Handpick cabbage worms and caterpillars. Check the undersides of leaves.
- Apply diatomaceous earth around plants to deter slugs and snails.
- Plant companion flowers like marigolds and nasturtiums to attract beneficial insects.
Regional Considerations For Oklahoma
Oklahoma spans multiple USDA hardiness zones, from 6a in the panhandle to 8a in the southeast. Your planting dates may vary by a week or two.
Northern Oklahoma (Zones 6A-6b)
In the north, frost comes earlier. Plant fast-maturing crops in early September. Use cold frames or row covers to extend the season.
- Focus on radishes, spinach, and arugula. They mature in 25-40 days.
- Plant garlic in late September for a strong start.
- Consider using a hoop house for tender greens.
Central Oklahoma (Zones 7A-7b)
This includes Oklahoma City and surrounding areas. You have a bit more time. Plant a mix of fast and slow crops.
- Broccoli and cauliflower transplants go in early September.
- Carrots and beets can be planted through mid-September.
- Kale and collards will produce until December with protection.
Southern Oklahoma (Zones 8A)
Southern Oklahoma has milder winters. You can plant later and harvest longer. Consider a second round of planting in October.
- Plant lettuce and spinach in September, then again in October.
- Brussels sprouts do well here because they need a long, cool season.
- You can even try a fall crop of snap peas if planted by early September.
Common Mistakes To Avoid
Even experienced gardeners make mistakes in the fall. Here are the most common ones and how to avoid them.
- Planting too late: Count back from your first frost date. If a crop needs 60 days, plant it by mid-September at the latest.
- Ignoring soil temperature: Seeds need warm soil to germinate. If the soil is over 85°F, some seeds like spinach will not sprout. Shade the soil or plant in the evening.
- Overwatering: Cooler weather means less evaporation. Check soil moisture before watering. Overwatering leads to root rot.
- Skipping frost protection: Have row covers or old sheets ready for unexpected early frosts. They can save your crop.
- Planting the same crops as summer: Tomatoes, peppers, and eggplants will not produce in cool weather. Stick to cool-season vegetables.
Harvesting And Storing Your Fall Vegetables
Knowing when and how to harvest makes a big difference in quality and storage life. Here are tips for each category.
Leafy Greens
Harvest outer leaves first, leaving the inner ones to grow. This method, called “cut and come again,” extends your harvest for weeks.
- Spinach and lettuce: Harvest when leaves are 3-4 inches long.
- Kale and collards: Pick the largest leaves from the bottom up.
- Swiss chard: Cut stems 1-2 inches above the soil line.
Root Vegetables
Roots are ready when they reach the size you want. They can stay in the ground for weeks if mulched heavily.
- Carrots: Harvest when the top is ½-1 inch in diameter. They get woody if left too long.
- Beets: Harvest at 1-2 inches for tender roots. Larger beets are tougher.
- Radishes: Harvest as soon as they are marble-sized. They become pithy if left.
- Turnips: Harvest at 2-3 inches. The greens are also edible.
Brassicas
Harvest broccoli when the heads are tight and dark green. Cauliflower heads should be white and compact. Cabbage heads should be firm.
- Broccoli: Cut the main head with 6 inches of stem. Side shoots will form later.
- Cauliflower: Cut the head when it is 6-8 inches across. Leave some leaves attached.
- Cabbage: Cut at the base when the head is firm. Store in a cool place.
- Brussels sprouts: Harvest from the bottom up when sprouts are 1-2 inches across.
Storage Tips
Most fall vegetables store well in a cool, dark place. A root cellar or a refrigerator works well.
- Leafy greens: Wash and dry thoroughly, then store in a plastic bag with a paper towel.
- Root vegetables: Remove greens, then store in a perforated plastic bag in the fridge.
- Brassicas: Store in the fridge. Cabbage and Brussels sprouts keep for weeks.
- Garlic and shallots: Cure in a warm, dry place for 2-3 weeks, then store in a cool, dark place.
Frequently Asked Questions
Here are answers to common questions about fall gardening in Oklahoma.
What vegetables can I plant in September in Oklahoma?
You can plant leafy greens like spinach, lettuce, and kale, root vegetables like carrots and beets, and brassicas like broccoli and cabbage. All of these are the best vegetables to plant in September in Oklahoma.
Is it too late to plant tomatoes in September in Oklahoma?
Yes, it is generally too late for tomatoes. They need warm weather and a long growing season. Focus on cool-season crops instead.
How do I protect my fall garden from frost in Oklahoma?
Use row covers, old blankets, or plastic sheeting supported by hoops. Remove covers during the day if temperatures rise above 40°F. Water the soil before a frost to release heat at night.
Can I plant garlic in September in Oklahoma?
Yes, late September is ideal for planting garlic. Plant individual cloves 2 inches deep and 6 inches apart. They will overwinter and produce bulbs next summer.
What is the best way to water a fall garden in Oklahoma?
Water deeply once or twice a week, depending on rainfall. Use drip irrigation to keep leaves dry and prevent disease. Morning watering is best.
Final Tips For A Successful September Garden
Oklahoma’s fall weather can be a challenge, but with the right choices, you can enjoy fresh vegetables well into winter. Start with a small patch if you are new to fall gardening. Focus on crops you love to eat.
Keep a garden journal to track what works and what doesn’t. Note planting dates, frost dates, and harvest times. This will help you improve each year.
Remember to check your local extension office for specific advice for your county. They have planting calendars and soil testing services that are very helpful.
With a little effort, you will be amazed at how much you can grow in the cooler months. The key is to start now, while the soil is still warm and the days are long enough for good growth. Happy planting!