Are you struggling on how to grow big broccoli heads in your garden? If your broccoli plants are producing small, underwhelming heads or bolting too soon, you might need to adjust your strategy. With the right timing, planting methods, fertilization, and variety selection, you can grow big broccoli heads that are worth the effort.
I’m growing broccoli in Florida’s warm climate, so these tips are especially useful for Southern gardeners, but they apply to anyone looking to maximize their broccoli harvest. Stay tuned, especially for tip number five—it’s the most important factor for success.
Table of Contents
1. Plant at the Right Time
Broccoli thrives in cool temperatures. Even if your seed packet says “heat-tolerant”, broccoli still prefers cool weather—and that means you need to plan your planting schedule carefully.
In Florida and other southern regions, broccoli should be planted in the fall and winter to ensure it matures in the right conditions. I start my broccoli seeds in September when it’s still hot, but I keep them in a shaded area until they’re ready to transplant. My planting schedule details out exactly when to start any veggie in Florida so check that out.
- Cool temperatures at harvest time: Broccoli does best when daytime temperatures are below 75°F and nighttime temperatures are at least 60°F.
- Avoid late planting: If you plant too late and your broccoli matures in spring or summer, the heat will cause the heads to bolt (flower too quickly) and turn bitter.
- Cold tolerance: Broccoli can withstand freezing temperatures down to 25°F, so don’t be afraid to plant it in late fall if you’re in a cooler climate. If a hard freeze is coming, just cover your plants for protection.
If you’ve been planting your broccoli in the spring, you might need to rethink your timing. Growing broccoli when it’s too warm is one of the biggest reasons people struggle with how to grow big broccoli heads.
2. Direct Seeding vs. Transplanting
Should you direct seed your broccoli or start it in trays?
Technically, broccoli can be direct-seeded, but I always start mine in trays first. Here’s why:
- Early season heat: September is still very hot in Florida, and seedlings are vulnerable to sun and pests. By starting in trays, I can keep them shaded and protected.
- Hurricane season & rain: Heavy rain in early fall can wash away or drown seedlings, but in trays, I can control watering.
- Stronger transplants: By the time my seedlings are ready to go in the garden (about 4–6 weeks old), they are sturdy and well-established, giving them a better chance to grow big broccoli heads.
For gardeners in cooler climates, direct seeding might work fine if you plant early enough. But if you’re growing broccoli in warmer fall weather, starting in trays gives you better control.
3. Fertilize Properly for Maximum Growth
Broccoli is a heavy feeder, and fertilization is critical to growing big broccoli heads. When you transplant your seedlings into the garden, you need to add fertilizer right away.
Here’s what I use:
- Blood meal: One of the best organic nitrogen sources, blood meal encourages strong leafy growth. I apply ⅓ lb per 8X4 garden bed, mix it into the soil, and water it in before planting.
- Granular fertilizers: Products like Espoma Garden-tone, Down to Earth, or Nutri-Rich are excellent choices because they slowly release nutrients over time.
- Liquid fertilizers: Fish emulsion or compost tea can be used for a nitrogen boost, but they need to be applied every 1–2 weeks, which can be time-consuming.
I only fertilize once at planting time using granular fertilizers, and my broccoli thrives all season. If you prefer using liquid fertilizers, be prepared to fertilize regularly—otherwise, your plants won’t have enough nutrients to grow big broccoli heads.
4. Harvest at the Right Time
Knowing when to harvest is key to getting the best-tasting, largest heads of broccoli. If you wait too long, broccoli will start bolting (flowering), and the quality will decline.
How to tell if your broccoli is ready:
- Tightly packed florets: When the broccoli head is young, the buds are small and compact. Once they start separating, harvest quickly.
- No yellow flowers: If you see tiny yellow flowers forming, it’s time to harvest immediately—or you’ll end up with bitter-tasting broccoli.
5. Choose the Right Variety
One of the biggest mistakes gardeners make is choosing the wrong variety of broccoli. Many of the common seed packets from big-box stores are small to medium head varieties—no matter how well you grow them, they won’t get very big.
For large broccoli heads, look for these varieties:
- Green Magic: Produces large 6–8” heads, great for warm climates.
- Arcadia: My personal favorite, but harder to find. It consistently produces big, full heads.
- Imperial: Grows well but tends to be smaller than Green Magic.
- Waltham & De Cicco: More common but naturally smaller-headed varieties.
Pro tip: When buying broccoli seeds, check the seed description. If it says “3-inch heads” or doesn’t mention head size, it’s probably a small or medium variety. Look for 6–8” head sizes for the best results.
Should You Grow Sprouting Broccoli?
Some varieties, like broccolini or purple sprouting broccoli, are designed to produce smaller florets instead of one large head. These types are more heat-tolerant and great for continuous harvests, but if your goal is to grow big broccoli heads, avoid sprouting varieties.
Bonus Tip: Keep the Plants for Side Shoots
Even after harvesting the main head, don’t pull up the plant! Broccoli will continue to send out side shoots for weeks, giving you extra harvests.
The first round of side shoots is usually decent-sized, but after 3–4 rounds, they’ll become much smaller. At that point, you can remove the plant and make room for a new crop.
Final Thoughts on How to Grow Big Broccoli Heads
If you’ve been struggling with how to grow big broccoli heads, the five key factors to focus on are:
- Plant at the right time – Grow during cool weather, not spring or summer.
- Start in trays – It helps protect young plants from heat and pests.
- Fertilize properly – Use granular fertilizers for long-lasting nutrients.
- Harvest before bolting – Don’t wait too long, or your broccoli will flower.
- Pick the right variety – Choose large-head types like Green Magic or Arcadia.
By making these simple changes, you can dramatically improve your broccoli harvest and start growing the large, healthy heads you’ve been hoping for. Happy gardening, and may your broccoli heads be bigger than ever!