The minimum spacing broccoli needs is 12 inches between plants. You can push them this close, but your harvest will look different than plants with more room. Expect smaller heads and fewer side shoots when you plant tight.
I tested this broccoli plant distance in my raised beds two seasons ago. Half the bed got 12-inch spacing. The other half got 18 inches. Both produced edible heads, but you could spot the differences right away. My kids even noticed which side grew bigger crowns.
The tight side grew heads about half the size of the roomier plants. We're talking baseball-sized heads versus softball-sized ones. The crowded plants also stopped producing side shoots after I cut the main harvest. My wider-spaced plants kept giving me bonus broccoli for another six weeks.
Here's why close broccoli spacing creates these trade-offs. At 12 inches apart, root systems start overlapping. Broccoli roots spread 18-24 inches wide under ideal conditions. When you cram plants together, those roots fight for the same water and nutrients in the soil.
Utah State University research backs up what I saw. Their studies show that 1x1 foot spacing cuts side shoot growth. Plants spend energy surviving the crowding. They have less left over to build bigger heads for your table.
The nutrient fight stays mild at 12 inches. Roots overlap at the edges but still reach separate soil near their stems. Go tighter than 12 inches and you'll see stunted plants everywhere. Your leaves turn yellow. Florets stay too small to bother harvesting.
So when does minimum spacing make sense for you? Small gardens gain the most from tight planting. If you have limited square footage, fitting six plants beats fitting four. You'll harvest more total pounds even though each head weighs less.
I also tried tight spacing again last year with the same results. You get more plants but smaller heads every time. The math works out similar in total yield, but you save garden space for other crops.
Growers who want lots of heads should consider 12-inch spacing. Restaurant gardeners plant tight since small heads sell just as well. Home cooks feeding big families follow this same plan when they need volume.
For the biggest heads and longest harvests, you should stick with 18 inches between plants. This spacing lets your roots spread without fighting. Your main heads will weigh 1-1.5 pounds instead of 8 ounces. Side shoots keep coming for weeks after you make the first cut.
My advice: match your spacing to your goals. Want maximum plants in minimum space? Go with 12 inches and expect modest heads. Want prize broccoli? Give each plant the 18-24 inches it prefers. Either approach works when you plan for what you'll get.
Read the full article: Broccoli Plant Spacing for Maximum Yields
