Spice Up Your Garden with Nasturtiums

Nasturtiums are an excellent addition to your garden and dinner table. Photo courtesy of allispossible.org.uk.

If you are looking for a striking annual that flourishes in Alaska and doubles as a culinary delight, you may consider giving nasturtiums a try. By following a few simple tips, these flowers are a fun and easy addition to containers and garden beds, and are a hit with adults and children alike.

Nasturtiums (genus Tropaeolum), have lush foliage, vibrant flowers, a pleasant fragrance, and are attractive to garden pollinators. However, it is their flavor that really makes them stand out in the crowded world of Alaskan annuals. In fact, the name nasturtium translates from Latin as “nose-twister”, conjuring up images of the face you might make after your first bite! Nasturtiums received their common name because they produce an oil that is similar to watercress (Nasturtium officinale).

The buds, flowers, seeds, and young leaves of this genus are edible and have a peppery flavor ranging from mild (buds and flowers) to intense (seeds). In addition to their flavor, nasturtiums are appealing because of their high content of vitamins A, C, and D. Typically, flowers and young leaves are used in salads and stir-fries. Seeds can be used to flavor oils or may be ground for a pepper substitute. Buds and immature seed pods can be pickled and used in place of capers, although some say that the buds should be ingested small quantities, as they are high in oxalic acid.

Nasturtium flowers and young leaves are an attractive and tasty addition to salads. Photo courtesy of the Nebraska Herbal Society.

The nasturtiums grown in gardens today descend primarily from two species native to Peru. These species were introduced to Europe in the late 15th and 17th centuries, and quickly became widespread. Nasturtiums were recorded in the US as early as 1759. From at least 1774 onward, Thomas Jefferson planted them in his vegetable garden in Virginia. Early species of nasturtium were trailing or semi-trailing in nature with orange flowers. Over time breeders have produced varieties that are smaller and more compact, along with those exhibiting different flower shapes and colors.

There are many articles and discussions online that provide information on growing nasturtiums. I have included links to a small selection of these articles at the end of this post. Here are three tips to help you successfully grow great nasturtiums. These tips are based on my experience and observations in the Anchorage area.

Tip #1: Nasturtiums need space to spread

Nasturtiums do well when seeded directly into garden beds or containers. They also do well as transplants. In both cases, it is important to provide plants with adequate space. Trailing varieties can get quite large; I have seen plants on a second-story apartment balcony trailing all the way to the walkway below!

When designing gardens or containers it is important to consider how your nasturtiums will spread. Nasturtiums are aggressive in both foliage production and rooting. They have a tendency to out-compete their neighbors by growing over them or by using a disproportionate amount of available water and nutrients. The latter is especially important to consider when designing containers. I have seen plants go into full wilt after the nasturtium flourishing next to them used all of the available water! If you are starting nasturtiums indoors, make sure to use an adequate pot size or your starts will quickly become root-bound.

Tip #2: Nasturtiums need proper nutrition

The prolific nature of many nasturtium varieties means that it is important to provide them with adequate nutrition. In garden beds, working in well-aged compost or manure before planting is often enough, but you may also want to consider adding an organic fertilizer. Try a fertilizer blend that includes one part blood meal to one half part bone meal and mix a handful into the soil at the time of planting.

Nasturtiums in containers will require fertilizer in order to thrive. Whether you select an organic or processed option, I have found that watering with a 12:9:6 quick-release fertilizer once per week works well. You can taper-off to less frequent fertilizing when plant growth slows in late summer.

If you notice that the leaves of your plants are turning yellow, it is likely a sign of nutrient (primarily nitrogen) deficiency. Luckily, nasturtiums respond quickly to liquid fertilizers. This summer, the leaves of nasturtiums I had growing in containers turned yellow despite the fact I was feeding them a 4:4:4 liquid fertilizer each time I watered. As soon as I switched to the 12:9:6 blend, the plants responded by producing dark green foliage and abundant blooms.

Tip #3: Nasturtiums need moisture, but don’t like to be soaked

Nasturtiums do well with even moisture or when they dry out between waterings. What nasturtiums do not like is to be soaking wet. This can be a challenge in rainy parts of Alaska. This summer was a rainy one in Anchorage and I watched a number of nasturtiums crash after being exposed to a series of downpours. Placing nasturtiums in areas where they will be protected from heavy rains will result in much happier plants.

With these tips and the resources below, you have all that you need to grow nasturtiums that will be both a feast for your eyes and tastebuds. Enjoy!

Additional Resources

Growing Tips: Nasturtium by the Denali Seed Company

Edible Landscaping – Edible of the Month: Nasturtium from the National Gardening Association Learning Library

Overview of Nasturtiums, their History and Uses from the University of Wisconsin System BioWeb

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