When To Plant Brussel Sprouts In Oklahoma

If you’re planning your Oklahoma garden, knowing when to plant brussel sprouts is key to a successful harvest. Getting the timing right in our state’s unique climate makes all the difference between a bumper crop and disappointment.

Brussel sprouts are a cool-season crop that thrive in our springs and falls. They need a long growing season, often over 100 days from transplant to harvest. The trick is to time it so the plants mature during cool weather, as frost actually improves their flavor.

For most of Oklahoma, you have two main planting windows: one in early spring and a better one in late summer for a fall harvest. The fall planting is often more succesful because the sprouts mature during steadily cooler temperatures.

Spring Planting Schedule

Spring planting is a race against the coming summer heat. You need to start early.

Start Seeds Indoors: Begin your seeds indoors about 6-8 weeks before your last average spring frost date. For central Oklahoma, this is typically late January to early February.
Transplant Outdoors: Harden off and transplant your seedlings into the garden 2-4 weeks before the last frost, when they are about 4-6 inches tall. This is usually mid-to-late March.
Direct Seed (Risky): You can direct sow seeds in the garden as soon as the soil is workable in very early spring, but growth is slow in cold soil.

The goal is to have the plants mostly matured before the intense Oklahoma summer heat arrives in July, which can cause the sprouts to be loose or bitter.

Fall Planting Schedule (Recommended)

The fall planting schedule is more reliable and yields sweeter sprouts. You work backwards from your first fall frost.

Calculate Your Date: Find your average first fall frost date (e.g., early November for OKC). Count backwards 90-100 days for maturity, plus about 3 weeks for seedling growth.
Start Seeds Indoors: Start your seeds indoors in mid-to-late June. This protects them from the brutal summer heat at their most vulnerable stage.
Transplant Outdoors: Transplant your sturdy seedlings into the garden in late July or early August. They’ll grow through the warm weeks and then form sprouts as nights get cooler.

The plants will mature during the crisp fall weather, and a light frost or two will sweeten the flavor perfectly.

Oklahoma Climate Considerations

Our state’s weather is full of suprises. Here’s what to watch for.

Heat: Prolonged temperatures over 75°F can halt sprout formation and cause bitterness. This is why fall planting is superior.
Wind: Oklahoma wind can damage tall, top-heavy plants. Use sturdy stakes and consider a windbreak if your garden is exposed.
Variable Frost Dates: Always be prepared with row covers or old sheets to protect young plants from a late spring frost or an early fall frost.

Step-by-Step Planting Guide

Follow these steps to get your brussel sprouts off to a strong start.

1. Choosing the Right Variety

Select varieties known for heat-tolerance and suited to our shorter springs and long falls. Good choices include ‘Long Island Improved’, ‘Jade Cross’, and ‘Churchill’.

2. Preparing Your Garden Bed

Brussel sprouts are heavy feeders. They need full sun (at least 6 hours) and fertile, well-draining soil.

Work in 2-3 inches of compost or well-rotted manure.
Add a balanced, slow-release organic fertilizer into the soil before planting.
Ensure the soil pH is between 6.0 and 7.0.

3. Transplanting Seedlings

Harden off indoor-started seedlings for a week before transplanting.
Space plants 18-24 inches apart in rows 30 inches apart. They get big!
Plant them slightly deeper than they were in their pots, up to their first set of true leaves.
Water deeply immediately after planting.

4. Essential Care Through the Season

Consistent care is non-negotiable for tight, firm sprouts.

Watering: Provide 1-1.5 inches of water per week. Drip irrigation is best to keep leaves dry and prevent disease.
Mulching: Apply a 3-inch layer of straw or shredded leaves to conserve moisture, suppress weeds, and keep soil cool.
Fertilizing: Side-dress with a nitrogen-rich fertilizer when plants are about 12 inches tall, and again when small sprouts begin to form.
Pest Watch: Scout regularly for cabbage loopers and aphids. Use row covers or organic controls like Bt (for caterpillars) as needed.

Harvesting Your Oklahoma Brussel Sprouts

Harvest begins from the bottom of the stalk upward. Pick sprouts when they are firm, about 1-1.5 inches in diameter.

Snap or cut off the sprout, leaving the leaf just below it to encourage further growth up the stalk.
For a single, large harvest, you can cut the entire stalk once the lower sprouts are mature.
A hard freeze is coming, you can pull up the whole plant and hang it in a cool garage to harvest sprouts for several more weeks.

Common Problems and Solutions

Even experienced gardeners face challenges. Here’s quick fixes.

Loose, Poorly Formed Sprouts: Usually caused by too much heat or not enough water. Stick to fall planting and maintain consistent moisture.
Yellowing Leaves: Could be a sign of nitrogen deficiency. Apply a liquid fertilizer.
Small Holes in Leaves: Likely cabbage worms. Hand-pick or apply an organic insecticide containing spinosad.

FAQ: Planting Brussel Sprouts in Oklahoma

Can I plant brussel sprouts directly in the ground in Oklahoma?
You can, but it’s less reliable. For spring, cold soil slows germination. For fall, the extreme July heat can stress young seedlings. Starting indoors is generally recommended for better control.

What is the latest I can plant brussel sprouts for a fall harvest?
Aim to have transplants in the ground by mid-August at the absolute latest for central Oklahoma. Later planting risks the sprouts not maturing before a hard freeze halts growth.

Do brussel sprouts come back every year?
No, they are biennials grown as annuals. They complete their life cycle (grow, produce sprouts, then go to seed) in two growing seasons, but we harvest them in the first year.

How do I protect my brussel sprouts from Oklahoma’s late spring frost?
Use a floating row cover, cloche, or even an old bedsheet to drape over the plants on cold nights. Just remember to remove it during the day so pollinators can access the plants if they flower.

Can I grow brussel sprouts in pots in Oklahoma?
Yes, choose a large container (at least 12-15 gallons) with excellent drainage. Use a high-quality potting mix and be vigilant about watering and fertilizing, as pots dry out and deplete nutrients faster.

With the right timing and a little attention, you can enjoy a plentiful harvest of homegrown brussel sprouts. Their sweet, nutty flavor after a frost is a true reward for the Oklahoma gardener’s patience and effort.