The best companion plants asparagus does well with are tomatoes and basil. Parsley, dill, and nasturtiums also make great plants with asparagus in your garden beds. Each one helps your garden in ways beyond just filling empty spots around the asparagus.
I plant tomatoes next to my asparagus every year and the combo works great for both crops I grow. Asparagus sends out chemicals that push away tomato hornworms from the area. Tomatoes then help keep asparagus beetles away too. West Coast Seeds and other sources confirm this two-way pest control works in real gardens like mine.
Plan your asparagus garden companions around the tall ferns that grow after harvest ends in late spring. Those ferns reach 6-8 feet (1.8-2.4 m) high by midsummer in most gardens. They cast shade on nearby plants all day long. Put sun-loving crops like tomatoes on the south side of your bed where they get full light. Set herbs like parsley where the ferns will block hot afternoon sun.
Herbs do double duty when you plant them with asparagus in your garden space. Basil and dill attract tiny wasps that eat asparagus beetle eggs each season. Parsley draws in the same helpful bugs that prey on garden pests. Nasturtiums act as trap crops that pull aphids away from your other vegetables in the garden.
Some plants hurt asparagus more than they help so keep them far away from your asparagus bed. Onions, garlic, and other alliums compete for the same nutrients in the soil. They can stunt asparagus root growth over time if planted too close together. Potatoes and beans attract pests that also attack asparagus plants in your garden area.
Leave at least 18 inches (45 cm) between asparagus rows and your companion crops so both can thrive well. This gives roots room to spread out as they grow over the years. Asparagus roots grow wide and deep over time and need their own space to stay healthy. Crowding them with other plants too close will hurt both crops in your bed.
Pick your spring asparagus before you set out tomato plants nearby in the garden bed. This timing gives you a clear work area and lets you enjoy fresh spears first. Then the summer ferns and tomato plants can grow up together side by side. They will not get in each other's way when you plan your timing right each year in your garden.
Read the full article: How to Grow Asparagus from Crowns Successfully
