Purple sprouting broccoli is a permaculture sweetheart, and for good reason: it provides harvests during the dreary “hunger gap” of early spring when your pantry is going bare and there’s not much to harvest from the garden.

On top of that, purple sprouting broccoli grows over winter, so in most climates the fall and spring rains hydrate your plants thoroughly.

However, if you’re like me, you may have experienced these struggles with overwintering purple sprouting broccoli:

• plants dying due to winter temperatures in the teens
• plants bolting after just a couple of small harvests
• pests demolishing your plants
• unimpressive harvests

It’s extra frustrating to tend to a plant for a whopping 220 days to get so little in return.

But I believe in purple sprouting broccoli, and after testing a few things out, I have gotten bigger harvests this year. And I’m planning on a bigger harvest still next year.

Here are the improvements I’ve made, and what I’m doing going forward to get even better results.

Purple Sprouting Broccoli: What to Know

• Cold Tolerance: In my experience, it does not like temperatures below 18°F / -8°C
• Typical Time to Maturity: 180-220 days (no, that’s not a typo); needs to overwinter in order to produce
• Best Time to Sow: July in most climates, or about 9+ months before your last frost
• When to Harvest: Purple sprouting broccoli typically produces heads in April, May, and June

Problem 1: Cold Temps Kill Purple Sprouting Broccoli Plants

• USDA growing zone 8 or above: you’ll probably not have an issue with this.
• USDA growing zones 6+7: In zone 7, I sometimes get temperatures that are around 13-18°F. Although it’s rare, when these temperatures last for a few days, it can be detrimental to my PSB plants.
• USDA growing zones 4+5: Your plants probably suffer due to the standard cold temperatures you experience in the winter.

How to Protect Overwintering Purple Broccoli from Frost:

• Locally Adapted Seeds: Buy your PSB seeds from a producer who is local to you or at least who has a similar climate. This will mean that seeds have been selected to last through your winters. Purple Reign is a promising choice selected for cold hardiness.
• Save Your Own Seeds: I am experimenting with saving seeds from ideally performing PSB plants - ones that survived the winter temperatures AND didn’t bolt too early in the spring.
• Establish Your Plants Early: PSB plants that are well established before your first frosts tend to perform best with cold temperatures. In my experience, bigger plants can come back from near-death to produce a harvest. Sow your seeds in late June through July for best results.
• Grow in a Greenhouse or Row Cover: This year, I’m going to grow PSB in my greenhouse to see how that affects overall performance.
• Grow in Containers: Plants get massive, so grow bags over 15 gallons are necessary. But you can move your plant around to ideal locations to prevent heat and cold stress.

Problem 2: Plants Bolt Shortly After Production

If you’ve ever experienced a warm spell in April or May, you’re probably familiar with the frustration of seeing your purple sprouting broccoli bolt after just a couple of small harvests.

Trust me, I’ve been there. It's especially disheartening when, not too long ago, you were nurturing them through the chilly weather, hopeful for a bountiful season.

But keep your chin up! There’s hope for your hunger gap cravings yet.

How to Prevent Purple Broccoli from Going to Seed:

• Strategic Planting: Do you have a spot in the garden that receives shade in the summer from a tree that looses its leaves in the winter? This might be the perfect spot to plant your PSB. By the time you get that early hot spell, the tree will provide some shade for your broccoli plant to prevent bolting. This also works with vining plants. Block sunlight with a trellis of spring peas if you need to create your own late-spring shade.
• Opt for Early Varieties: Some varieties, like Arrow, will produce crops as early as late February. This means you’ll be able to harvest for a few months before your first warm spell.
• Opt for Late Varieties: Summer Purple Broccoli from West Coast Seeds starts to produce heads in June, with the potential for continual harvests into October! Still best for mild summer climates.

Problem 3: Pests Destroying Your Purple Sprouting Broccoli Seedlings

Gardeners aren’t the only ones who delight in seeing the huge leaves of purple sprouting broccoli plants. Turns out we have a bit of competition:

• Slugs
• Cabbage Worms
• Cabbage Looper
• Aphids

Solutions for PSB Pests:

• Transplant Established Seedlings: Start PSB indoors in late June/early July to give them a head start. Water them well and provide a balanced organic fertilizer upon transplant so that they do not suffer from stress.
• Netting: Insect netting over your PSB will prevent cabbage moths from laying eggs on your plants. I’ve also found this to be an effective way to manage slug damage.
• Double up: While not everyone will have the room for this solution, I tend to plant out twice as much brassicas as I need, knowing that some will get damaged by pests as they mature.
• Companion Planting:
  • Marigolds are slug magnets, and can deter them from your broccoli plants.
  • Chamomile can deter slugs and other pests - I plant it everywhere in my garden.
  • According to a study from Iowa State University, thyme, nasturtium, and onion help prevent cabbage worm and looper damage from brassicas.

Problem 4: Unimpressive Purple Sprouting Broccoli Harvests

If you’ve grown purple sprouting broccoli in the past, you may have had a plant give you minimal harvests. Yes, it’s called sprouting broccoli, but 2-3 sprouts ready to harvest at a time isn’t going to provide much sustenance to dinner.

Solutions for Bigger PSB Yields:

There are a few things I’ve done to help improve PSB yields.

• Early Start: Plants that I started off in late June gave me bigger harvests than those with a July sowing. Thanks to Huw Richards for this tip!
• Continual Harvests: Even though it can feel not worth your while to pick small florets off your PSB, keeping the plants free of sprouts will encourage it to produce more.
• Pruning: Instead of harvesting just the sprouts, I like to prune back the stems to the base of the plant. Removing all stems seems to trigger the plant to create more florets.

Other Purple Sprouting Broccoli Tips

Here are some other things I do to help my PSB plants be as healthy as possible:

• Organic Fertilizer: Provide an organic nitrogen-rich fertilizer as the plant is getting established. I like to use feather meal every 3 weeks until we’ve had our first frost.
• Mulch: In the heat of the summer when plants are getting established, mulch supports the water retention of the surrounding soil. Mulch also helps protect the plants from low temperatures throughout the winter.
• Crop Rotation: Plant your purple sprouting broccoli after you harvest your garlic or onions, and try to go a few years between planting any brassicas in the same area. Crop rotation helps to reduce soil-borne pests and other disease issues that can be detrimental to your harvests.
• Spacing: If you can, space your PSB plants 2-3 feet apart. They get quite big and a wider spacing will allow the plants to get better air flow and circulation.

Purple Sprouting Broccoli Alternatives

You might feel ready to go forth into another PSB season with confidence, excited for the potential of a bowl of fresh broccoli before spring. Or you might be wondering if you should look elsewhere for your brassica fix.

My inclination is to say “why not both”? Here are some options that give you a sprouting broccoli kind of plant without the 220 day wait.

• Broccoli Raab: Broccoli raab, AKA rapini or Cima di Rapa, is a sprouting broccoli that has a fast 45-60-day maturity window.
• Chinese Broccoli: Harvest the florets with the leaves and thin stem, matures in 45-60 days.
• Perennial Tree Kale: While it doesn’t make florets, once it establishes in your garden you’ll have year-round leafy green harvests.
• Green Sprouting Calabrese: A 60 day time to maturity makes this a great pick for anyone who struggles with PSB’s long growing season, but want smaller continual florets.

Frequently Asked Questions About Growing Purple Sprouting Broccoli

Q1: How often should I water purple sprouting broccoli?

A1: Consistent moisture is key. Water your purple sprouting broccoli plants deeply and regularly, especially during late summer dry spells. Aim to keep the soil evenly moist but not waterlogged. Mulching can help retain soil moisture and reduce the need for frequent watering.

Q2: Can I grow purple sprouting broccoli in partial shade?

A2: Yes, purple sprouting broccoli can tolerate partial shade, especially in warmer climates. In fact, some afternoon shade can help prevent bolting during unexpected warm spells in spring.

Q3: How do I know when to harvest my purple sprouting broccoli?

A3: Harvest your purple sprouting broccoli when the heads are fully formed but before the flowers start to open. The ideal time is typically in early spring, but it can vary depending on your planting schedule and climate. Regularly check your plants for the first signs of sprouting.

Q4: Can I save seeds from my purple sprouting broccoli plants?

A4: Yes, you can save seeds from your best-performing plants to cultivate varieties that are well-adapted to your local climate. Allow some plants to flower and set seed, then collect and store the seeds in a cool, dry place for the next season.

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