From fixing nitrogen in the soil to actively detoxifying it, plants have incredible powers to improve the environment for themselves and the plants around them. Plants that are commonly found in home gardens, like marigolds or sunflowers, and plants you may never have heard of, like Illinois bundleflower, can help enrich your garden soil. You just need to pick the best soil-enriching flower to address your soil’s deficiencies.

Long taproots break up compacted soil and can help bring nutrients that are deep down in the ground up to the surface, where other plants can access them. Other plants can help remove heavy metals left behind in the soil. Not sure what problems your soil might be suffering from? Sometimes identifying the weeds in your yard can tell you a lot about what’s happening beneath the surface. For instance, a yard full of dandelions can tell you a lot about your soil’s condition. So, be sure to put the right plant in the right location by first understanding the problems you need to confront.

A frequent sight in many gardens and wildflower fields across the country, lupine (Lupinus perennis) was once thought to deplete the soil — but, boy, were they wrong. As a legume, lupine actually helps fix nitrogen into the soil. Different varieties are native to different parts of North America, but it should be easy to find one for your neck of the woods. Native varieties are typically blue or purple, but cultivars come in many colors. Typically about 2 feet tall, they enjoy full sun or partial shade. Lupine is hardy in USDA Zones 3 to 8. 

Borage (Borago officinalis L.) also has lovely flowers, and planting borage in your garden has many benefits. It has a deep taproot that helps break up heavy, clay, or compacted soil, and it attracts beneficial insects. While beneficial insects won’t necessarily improve your soil, they can help reduce your dependence on chemicals, which is good for the soil. More directly, the taproot will make it easier for water to penetrate the ground. Plant with care, as borage is an annual that grows in USDA Zones 2 to 11, and it can become weedy in some cooler climates.

If you want to stick with the blue and purple theme while also adding more nitrogen to the soil, consider wild indigo (Baptisia spp). Found in woodland borders from the eastern to midwestern U.S., these plants are especially easy to care for. They can thrive in full sun or partial shade, handle drought, poor soil, and even some soil erosion. A long taproot makes it hard to transplant, so make sure you’re happy with wherever you plant it. Bees and other pollinators are big fans of wild indigo, which grows naturally in USDA Zones 5 to 8. 

You can spot a sunflower (Helianthus annuus) from miles away, usually because they are planted densely in huge fields. Many fill their field with sunflowers just because they are beautiful, but they are also phytoremediators, which help detoxify the soil. Yes, sunflowers can actually help remove heavy metals from the soil. They have extensive root systems and long taproots to support their large size, which also helps break up the soil, so if you want to clear the traces of old fertilizers or other contaminants from your garden, plant sunflower seeds. 

Don’t have room for nitrogen fixers like wild indigo or lupine? Maybe sweet pea (Lathyrus odoratus) can work for you. These climbing annuals can reach up to 8 feet tall and smell delightful. Start the seeds of these sweet flowers in winter for a beautiful spring display in May and June. The blooms will decline quickly once hot, humid summers set in. They like full sun and moist, well-drained soil. Move them around the garden from year to year to get the best results and improve your soil all over.

Comfrey (Symphytum officinale) is a clumping perennial that can grow up to 3 feet tall and almost as wide. Beautiful, bell-shaped flowers appear in May and June, but more importantly, it has an expansive root system, bringing many advantages to the soil. Not only do those roots break up the dirt, but they also help bring nutrients closer to the soil’s surface, helping the plants nearby access them. Comfrey, hardy in Zones 4 to 8, is a nitrogen fixer and a ground cover that naturally fertilizes fruit trees. Despite its benefits, comfrey is considered an invasive species in Oregon.

We hear a lot about marigolds (Tagetes spp.) being a great companion plant for their ability to repel pests, but did you know it does the same thing below the soil? They release a toxin into the soil that helps repel parasitic nematodes. So, while marigolds may not actively enrich the soil, they certainly make it a safer place for surrounding plants. The good news is they are easy and cheap to come by, and you may even already have them in your garden, as these annual plants easily self-seed.

Perhaps the most unique-looking choice on this list, Illinois bundleflower (Desmanthus illinoensis) is a North American native with an unusual, ball-shaped cluster of flowers that come in green or white. They bloom from May through September, and their deep taproots help break up the soil. They are also nitrogen fixers and are valued for the role they play in soil restoration projects. Wildlife love them too, including butterflies, so they should also be a good addition to pollinator gardens. This native is hardy in USDA Zones 4 through 8.