While planting certain plants next to pepper plants can aid their growth, other plants like brassicas, fennel, and nightshade can actually hinder their growth instead.

Plants in the brassica family like cauliflower, broccoli, cabbage, and kale crave the same nutrients as peppers. When planted together, they compete for nutrients in the soil.

By planting them far apart, each plant can better share nutrients while growing in the soil they prefer. Brassicas prefer a neutral soil while peppers want more acidic soil.

Fennel is best planted away from all other vegetables, peppers included. This is because some varieties (like Florence fennel) produce a chemical that can stop nearby plant growth.

Fennel also attracts swallowtail butterflies, which may lay eggs and give rise to caterpillars in your garden. They can make a feast of your pepper plants when hatched nearby.

Nightshade vegetables like potatoes and eggplants should be planted far from peppers with other plants between them since they are all susceptible to the same diseases.

Additionally, nightshade veggies can attract insects that eat peppers and need nutrients similar to what peppers need, so they’ll compete if grown near each other.