Nasturtiums are pretty, low-growing or climbing plants that bring a splash of bright, vibrant colour into any garden. They’re easy to grow, have plenty of benefits for your vegetable or herb garden, and are tasty too! What’s not to love!
The real challenge with nasturtiums is keeping them under control. They grow voraciously in the right conditions and can quickly surge over other plants, overtaking your flowerbeds and becoming a real pest.
In our guide, you’ll learn how to grow and care for nasturtiums, how to use them in the kitchen and – importantly – how to keep these pretty, useful plants under control.
What are Nasturtiums?
The nasturtium, also called Indian cress, Mexican cress or Peru cress originates from South and Central America, from the Tropaeolum genus (and NOT the genus ‘Nasturtium’, which is VERY confusing).
It’s a member of the Brassica family and is fully edible – flowers, leaves and green seed pods. It’s peppery, mustardy flavour is similar to watercress.
There are many different varieties of nasturtium, including climbing, trailing and dwarf varieties, all with bright orange, cream or yellow flowers through the warmer months and rounded, soft green leaves.
Are Nasturtiums Edible?
Yes! The flowers leaves and green seed pods are all edible and can be used as garnished, in salads, pastas, pickles and more. It has a peppery, mustard-like flavour similar to rocket or watercress.
How to Grow Nasturtiums
These are very easy plants to grow and care for, which is why they can take over a garden so quickly.
- Climate – These plants grow well in all Australian climates, and can handle light frost. Once established, these plants are tougher than they look and can be fairly drought- and temperature-resistant, although they may scorch a little in very hot environments.
If you see them start to wilt, give them some water and they will perk up quickly.
- Sun – They enjoy full sun and can grow in partial shade too, though they will not bloom as much.
- Water – Nasturtiums need an average amount of water and thrive in moist, well-drained soil.
- Soil – The soil should drain well and not be too boggy or clay. They enjoy fairly low levels of nutrients and produce more blooms in low fertile soil than in high fertile soil.
- Fertilizer – This plant generally needs no fertiliser. Adding fertiliser will produce more foliage and fewer blooms.
- Planting – They can be grown in flowerbeds or containers. For single plants, plant 30cm away from other plants. They can manage in fairly small containers, but grow well in standard herb containers (about 1 litre).
- Pruning – Deadhead regularly through the warmer months. If you are growing your plants in containers, you can trim them back over the growth season as needed. They respond to pruning very well, so if they start getting spindly and strung out, prune them back and thick, new growth will appear.
Nasturtium plants are very strong self-seeders, and even if your plant dies in a heavy frost or drought, new seedlings will pop up quickly as soon as the climate is right.
Companion Plants When Growing Nasturtiums
Nasturtiums are great companion plants for roses, vegetables and fruit trees, as the peppery oil in the plant attracts pests to its leaves and flowers – and far away from more vulnerable plants.
They attract predatory insects to feast on aphids and other pests too, helping to create a natural pest-trap and healthy biome in your garden.
Their heavy spread also makes them a great groundcover, suppressing weed growth and shading the soil to slow moisture loss.
They are commonly planted with apples, cabbage, tomato, corn, kohlrabi, radish, squash, melon and beans.
How to Grow Nasturtium from Seed
If you are growing nasturtium from seed, here’s what you have to do:
Soak the seeds overnight in water.
Plant when the soil is warm, in the spring or summer.
Poke holes 3cm deep and 10cm apart in the soil, placing one seed per hole.
Keep the soil moist until the plants are established. If you are growing them in the heat of summer in a container, try keep the container somewhere where it won’t catch the main heat of the day.
As the seedlings appear, which takes as little as 10-14 days, you can separate them to 30cm apart.
Pests and Diseases
Nasturtiums are very pest and disease resistant, attracting pests and predator insects to draw them away from other plants and crops with little or no damage to the nasturtium itself.
In very wet conditions, it may get powdery mildew or struggle to grow. This is best solved by planting seeds or plants in well-drained soil in a sunny or semi-shade spot.
You can also improve boggy and waterlogged soil by adding lots of organic compost and bark chips.
How to Harvest Nasturtium
The leaves, flowers and green seed pods of the nasturtium are all edible, and one of the best ways to keep this fast-growing plant under control is to harvest it frequently. Here’s how:
The plant is ready to harvest when it is about 15cm tall.
Gather blooms, leaves and green seed pods in the morning, before it gets hot. This is when the blooms are their most plump.
Snip away the base of each flower, as this can be a bit bitter.
How to Eat Nasturtiums
With their bright colours and piquant flavour, nasturtiums are a great addition to a wide range of foods. Here are some examples to help you use your nasturtiums in lunches and dinners.
- Salads – Use as a substitute for rocket or watercress in salads, mixing in full flowers and leaves for a beautiful dish.
- Cheese dishes – The mustard-like, peppery taste compliments cheeses well, and they make a great addition to cheese boards. You can also stuff the flowers with cream cheese or goat’s cheese, or as a garnish for cheese tapas.
- Dips and sauces – You can mince up your nasturtiums and mix with lemon butter to go on steaks, chicken, seafood or vegetables, or mince it into cream cheese dips.
- Pasta – The flowers and leaves add real wow factor and taste to pasta dishes, and you can add them whole or shredded for both vegetarian and meat based pastas to add a punch of flavour and colour.
- Pickles – Another good idea is to pickle the green seeds. They make a great substitute for capers!
- Stir fry – The leaves and flowers are a tasty, fresh addition to a stir fry, especially as a complement or replacement vegetable for spinach.
Why is it Important to Control Nasturtiums?
If you are new to gardening you might look at the picture of a nasturtium and be asking ‘why wouldn’t I let that plant grow, it looks beautiful!’
Indeed, nasturtiums are actually very attractive plants and it is for this reason they are not generally considered as weeds, because many people actually want to grow them.
The issue with nasturtiums is that they grow so very well and will, if allowed, just about take over any other plant in your garden. They grow so profusely that if left unchecked can actually cause a lot of stress to your other plants as they try and compete with the plant.
The other issue with nasturtiums is that once you plant them, or allow them to grow, they will come back year after year regardless of whether you want them to or not.
I moved into my current residence around August last year and haven’t seen a nasturtium growing until very recently.
Nasturtiums really do like autumn because the milder weather really suits them and gives them time to prepare either for the cold, wet of winter, or the dryer humidity in the tropics.
Just recently a few of these have started popping up all over my garden. They obviously start very small, but if I don’t decide soon if I want them or not, they will start to take over.
As beautiful as the flowers actually are, I am not generally a fan simply because of their growth habit. As such, my decision is to get rid of them.
How to Get Rid of Nasturtiums
Though I am sure there is a chemical way of doing it, I like to advocate a very simple, environmentally friendly way. So, how do you stop them taking over? Simple, pull them out when they are small! As soon as you see a nasturtium starting to grow in your garden, pluck it out.
You may not quite get all of its roots, but it will take a little while to grow back. Even better, dig down around it with a small hand shovel and make sure you’ve got it all.
A real benefit to this is it means you stop them before they get the chance to flower and drop seeds for next season. This will diminish the amount that returns next year, making your job easier.
Now, this isn’t foolproof because nasturtium seeds like to travel with the wind, so they can be blown onto your property from other people’s gardens, but if you at least stop ones on your property getting the opportunity to flower you will go a long way to eradicating them.
Of course, if you like them and don’t actually mind them taking over, if you see them growing in your garden just let them be! They really will take off without the need for any help and a garden bed covered in nasturtium flowers is actually quite nice.
Just be prepared - if you let them go crazy this year, expect them to be back in force in the future also.
This is just one of many plants you may discover ‘popping up’ in your garden as the weather warms up. Not all of them are as difficult a choice to keep or not because not all of them are nice!
The main thing to keep under control is any weeds that try and take over, very few ‘weeds’ are considered nice by anyone! Good luck.
Grow and Enjoy Your Nasturtiums!
Nasturtiums are beautiful, easy to grow, provide protection for plants and crops that are vulnerable to pests, and edible – making it an eye-catching, versatile and useful plant for your garden.
Once planted in a sunny spot (container or flowerbed), it takes care of itself and produces flowers, leaves and green seed pods for your salads, pastas, stir fry dishes and much more, adding a delicious peppery, mustard-like flavour.
Just remember that this plant self-seeds quickly and needs to be regularly trimmed and kept under control or it will take over your whole garden in just a few seasons!