Nasturtiums
Timothy Newcomb, Anoka County Extension Master Gardener
Starting a vegetable garden involves more than just giving plants space and water. We are creating a tiny ecosystem by providing a diverse mix of plants that contribute to the soil, pest protection, or bringing in pollinators. One nifty addition to any vegetable garden is the nasturtium. It is easy to grow, provides pest protection for other plants and its leaves and flowers are edible.
Nasturtiums (Tropaeolum) originate from central and South America where it grows as a perennial (zone 9-11). Up here in the chilly Midwest, our winters limit nasturtiums to being grown as an annual. They can be either started indoors in mid to late April or outdoors towards the end of May and will last until the first hard frost. If starting indoors, use paper-type starting trays that can be planted directly in the soil when ready to avoid transplant shock. The annual life cycle of nasturtiums can be a benefit for a garden because this matches the cycles of other vegetable plants.
Nasturtiums have peltate (disc-like) leaves that are typically two to four inches around and resemble tiny lily pads. Their flowers most commonly range in color from yellow to reddish orange though other varieties can be found. The flowers attract a range of pollinators including bees, butterflies and hummingbirds.
Nasturtiums can either be bush types around 12” tall while others are trailing and make excellent additions to pots, hanging over walls, or trained to grow up trellises. They grow best in full sun with well-drained soil. They will tolerate shade but will not bloom as abundantly there. Interestingly, nasturtiums tolerate and bloom best in poor, low nitrogen soils. Too much nitrogen encourages leafy growth at the expense of flower production. Be sure to deadhead flowers regularly to prolong the blooms.
The leaves and flowers have a spicy, peppery taste similar to watercress, that make great additions to salads. For the best flavor, harvest younger leaves and flowers, as older ones can be bitter. The flowers are milder in flavor than the leaves. When the summer turns hot the flavor gets spicier.
Several university studies have shown that nasturtiums can reduce pest pressure when planted next to brassicas (like broccoli and cabbage), squash and pumpkin plants.
While they are relatively resistant to pests, nasturtiums can attract cabbageworms and aphids. Diseases like bacterial leaf spot, and wilt may occur, but can generally be prevented by good watering practices including keeping the leaves dry when watering and pruning to promote airflow.
While nasturtiums offer many benefits to your garden, from attracting pollinators to deterring pests. They also remind us that gardening thrives on connection, and we gardeners grow stronger when we learn from each other's experiences and offer a helping hand.
Every year, Master Gardeners across Minnesota partner with the University of Minnesota to test different plant varieties for ease of growing, productivity, and flavor. This year, six varieties of nasturtiums are being trialed, and we’re excited to share the results with you early next year.
Until then, consider adding nasturtiums to your garden—not just for their beauty and utility, but as a reminder that vibrant gardens grow best in vibrant communities. Happy gardening!
