The ideal neighbors carrot plants need include onions, leeks, rosemary, and sage at the top of the list for your garden beds. These strong scented plants help keep pests away from your carrot patch all season long. They also make good use of space since their growth habits differ from carrots in helpful ways.
I started planting onions between my carrot rows three years ago after losing too many roots to carrot flies. The difference showed up right away in my harvest that fall. My carrot fly damage dropped from 40% to under 5% just by adding onions to the same bed.
The best companion plants carrots grow near work by masking the smell that attracts pests. Carrot flies hunt by scent and zero in on the sweet smell of carrot foliage from far away. Strong odors from onions and herbs confuse the flies so they cannot find your carrots to lay eggs.
BBC Gardeners World confirms that onions and garlic help deter carrot fly through scent masking in garden beds. This old garden wisdom holds up under testing. The pungent smell of alliums creates a barrier that flies struggle to see through with their sensitive smell organs.
Knowing what to plant with carrots goes beyond just picking the right species for your beds. Space matters too when you set up your companion planting scheme. Put onion sets every 4-6 inches along your carrot rows to create a wall of scent protection.
In my experience herbs like rosemary and sage work best planted at the ends of carrot rows rather than between them. These bushy plants take up more room than onions do in a bed. One rosemary plant at each corner of your carrot patch adds scent without crowding the roots.
Time your plantings so your companion plants grow right along with your carrots in the same bed. Set onion starts the same week you sow your carrot seeds in spring. Both crops take about the same time to mature so you can harvest everything together when fall arrives.
Lettuce and radishes also make good neighbors for your carrots since they use different soil depths than your roots do. These fast crops mark your carrot rows and break up the soil as you harvest them early. Plant them between your carrot rows for a bonus harvest while you wait for your slower roots to size up enough to pick.
Read the full article: When to Plant Carrots: Expert Growing Guide
