Gardening Tips
Top 10 Best Plants That Improve Soil Quality, Making Your Whole Garden Thrive
Healthy soil is the foundation of a thriving garden. While compost and other amendments can certainly help improve poor soil quality, there’s an even more beautiful solution—growing specific plants that naturally enhance your soil. Many gorgeous varieties can fix nitrogen, break up compaction, add organic matter, and even help control harmful pests. We’ve consulted with garden experts to bring you the top 10 plants that not only look stunning in your landscape but also work hard to transform your soil into a nutrient-rich growing medium.
Read more: How to Prepare Soil to Plant: A Step-by-Step Guide for Beginners
Top 10 Best Plants That Improve Soil Quality
These powerhouse plants naturally enhance fertility, reduce compaction, and boost your garden’s overall health.
Crimson Clover
Crimson clover (Trifolium incarnatum) produces striking crimson-red flower spikes that add a splash of color to your garden from spring through early summer. “This annual cover crop is one of the best nitrogen-fixers you can grow,” says Maria Johnson, a soil scientist at the University of Plant Sciences. The plant has specialized root nodules that capture nitrogen from the air and convert it into a form that plants can use. When the clover dies back or is cut down and allowed to decompose, it releases this nitrogen into the soil, benefiting nearby plants.
Zones: 6 to 9
Mature size: 18 to 24 inches tall x 12 to 24 inches wide
Care requirements: Full sun to part shade; adaptable to most soil types
Comfrey
Comfrey (Symphytum officinale) is a perennial herb that produces clusters of bell-shaped flowers in shades of purple, pink, or white from spring through summer. Its most impressive feature, however, lies underground. “Comfrey’s deep taproot can reach 8 to 10 feet into the soil, mining nutrients that are inaccessible to other plants,” explains Dr. Thomas Rivera, horticulturist at Green Earth Gardens. These nutrients are stored in the plant’s large, fuzzy leaves. When the leaves decompose, they release potassium, calcium, and other minerals back into the upper soil layers where other plants can access them.
Zones: 4 to 9
Mature size: 2 to 4 feet tall x 2 to 4 feet wide
Care requirements: Full sun to partial shade; moist, well-draining soil
Lupine
Wild lupine (Lupinus perennis) creates a stunning display with its tall spikes of blue-purple flowers that bloom from April through June. This native perennial isn’t just beautiful—it’s also working hard below the surface. “Like other legumes, lupines have symbiotic bacteria in their root nodules that convert atmospheric nitrogen into plant-available forms,” says Rivera. This natural fertilization process enriches the soil while the plant’s deep roots help break up clay or compacted soils, improving drainage and aeration.
Zones: 3 to 9
Mature size: 1 to 2 feet tall x 1 to 2 feet wide
Care requirements: Full sun to light shade; well-draining soil
Sunflowers
Sunflowers (Helianthus annuus) bring cheerful, sunny blooms to the garden throughout summer and into fall. Beyond their beauty, these plants are soil-improvement powerhouses. “Sunflowers have an extensive root system that penetrates deep into the soil, breaking up compaction and improving soil structure,” says Johnson. Their roots can reach depths of 3 to 5 feet, creating channels that allow water and air to move more freely through the soil. Additionally, sunflowers can help extract excess nutrients and even remove certain heavy metals from contaminated soils.
Zones: 2 to 11
Mature size: 3 to 10 feet tall x 1 to 3 feet wide
Care requirements: Full sun; moderately fertile, well-draining soil
Marigolds
Marigolds (Tagetes spp.) are beloved for their bright orange, yellow, or red blooms that provide color from spring until frost. “What many gardeners don’t realize is that marigolds are one of the best plants for soil pest management,” explains Rivera. Their roots release compounds that can suppress harmful nematodes and other soil-dwelling pests that damage plant roots. French marigolds (Tagetes patula) are particularly effective at controlling root-knot nematodes, while Mexican marigolds (Tagetes minuta) produce stronger compounds that can suppress a wider range of soil pests.
Zones: 2 to 11 (grown as annuals in most regions)
Mature size: 6 inches to 3 feet tall x 6 inches to 2 feet wide (depending on variety)
Care requirements: Full sun; tolerates most soil types
Fava Beans
Fava beans (Vicia faba) are cool-season legumes that produce attractive white flowers with black markings, followed by upright pods containing edible beans. “Fava beans are exceptional nitrogen-fixers that can thrive in cooler temperatures when other cover crops struggle,” says Johnson. Their strong root systems break up compacted soil, while the plants themselves add significant organic matter when turned into the soil. The beans can be harvested for eating, or the entire plant can be cut down just before flowering for maximum soil benefits.
Zones: 3 to 11
Mature size: 2 to 5 feet tall x 8 to 18 inches wide
Care requirements: Full sun to partial shade; well-draining soil
Buckwheat
Buckwheat (Fagopyrum esculentum) is a fast-growing annual that produces clouds of delicate white flowers that pollinators love. “This is my go-to plant for quickly improving poor soil,” says Rivera. “It can transform a plot in just 30 to 40 days.” Buckwheat’s fine roots create a dense network that improves soil structure, while also accessing phosphorus and calcium that other plants struggle to reach. When turned into the soil, buckwheat decomposes rapidly, releasing these nutrients. Its quick growth also suppresses weeds, giving you multiple benefits in a short time frame.
Zones: 3 to 10 (grown as an annual)
Mature size: 2 to 4 feet tall x 1 to 2 feet wide
Care requirements: Full sun to partial shade; adaptable to poor soils
Borage
Borage (Borago officinalis) is an herb with fuzzy leaves and striking star-shaped blue flowers that bloom from late spring through fall. “Borage is a magnet for pollinators and a wonderful soil builder,” explains Johnson. Its taproot breaks up compacted soil, while the plant accumulates potassium and calcium. Borage has hollow stems that decompose quickly when cut down, returning these nutrients to the soil. The plant also attracts beneficial insects that prey on garden pests, providing multiple benefits to your garden ecosystem.
Zones: 3 to 10 (self-seeds readily)
Mature size: 1 to 3 feet tall x 1 to 2 feet wide
Care requirements: Full sun to partial shade; well-draining soil
Daikon Radish
Zones: 2 to 11 (grown as an annual)
Mature size: 12 to 18 inches tall x 8 to 12 inches wide
Care requirements: Full sun; moderately fertile, well-draining soil
Alfalfa
Alfalfa (Medicago sativa) is a perennial legume with deep roots and clusters of purple flowers that bloom throughout the summer. “Few plants can match alfalfa’s contribution to soil health,” says Johnson. Its extensive root system, which can reach depths of 20 feet or more, breaks up compaction and improves soil structure at multiple levels. Like other legumes, alfalfa fixes nitrogen, but it also mines calcium, magnesium, iron, and other micronutrients from deep soil layers. These nutrients become available to other plants when alfalfa leaves drop or when the plant is cut back and allowed to decompose.
Zones: 3 to 9
Mature size: 2 to 3 feet tall x 1 to 2 feet wide
Care requirements: Full sun; well-draining soil
By incorporating these soil-improving plants into your garden design, you can naturally enhance soil fertility, structure, and health while creating a beautiful landscape. Many of these plants also support beneficial insects and pollinators, creating a more balanced and resilient garden ecosystem. Whether you dedicate a specific area to grow these plants or integrate them throughout your landscape, your soil—and all the plants growing in it—will thank you.
