How To Grow Nasturtium From Seed?

Nasturtiums are beautiful plants with bright red, orange, and/or yellow flowers that look great in gardens and as container plants.

Nasturtiums are a great addition to any garden. They look pretty and have aromatic flowers.

But these beautiful flowers aren’t just for decorative flower gardens anymore – they’re also a food crop!

They’re great additions to salads, desserts, and many other foods as a garnish.

There are other ways to propagate nasturtiums, such as through stem cuttings, but in this article, we’ll teach you how to grow and care for nasturtiums from seed.

How to Plant Nasturtium From Seed

You can plant nasturtium seeds directly in your garden soil or start them indoors. 

To jumpstart the germination process of the seeds, you may try soaking the seeds in water overnight before planting.

You should keep the soil moist constantly until they sprout. They usually sprout in about a week to 10 days and between 4 and 6 weeks to fully mature.

Look out for any specific instructions on your seed packet for different varieties of nasturtium.

When To Plant

Before even asking how we first must know when to start the seeds, so it matches the perfect weather to plant them.

Nasturtiums are cool-season annual flowers/ plants.

If you want blooms in spring and early summer, plant them after the last spring frost.

If you want winter blooms and you’re living in an area where freezes never come, plant them in autumn.

They can’t be planted outdoor until after the frosts pass, but you can start your seeds indoors so that you can transplant the nasturtium seedlings as soon as the weather warms up.

Start your seeds indoors 4 to 6 weeks before the last frost date. Check your local weather to calculate this. 

Sowing

For direct sowing/ outdoor starting:

The soil temperature should at least be 12 to 18 °Celsius at the time of planting or when you’re sure that the danger of frost has passed. 

Plant the seeds about 10 to 12 inches apart and cover them with soil, about 1/2 to 1 inch deep.

Tip!

If you plant them directly in your garden soil, make sure to mark and label where you planted them, so you don’t mistake them for weeds while they’re sprouting!

For indoor starting:

Nasturtium seeds are larger compared to other seeds, so you need a bigger starting pot.

Plant seeds in a 3-inch starting pot and about 1 inch deep in the soil.

Place the pot under a grow light or a south-facing window where it can get lots of light. Make sure to give it constant moisture, especially when under a grow light which tends to dry soil faster.

You can use regular potting soil and even your garden soil as long as it’s not cold.

Tips!

If you’re using your garden soil, leave them indoors in a warm place for 1 to 2 days to warm them up for the seeds. 

You can plant two seeds in one 3 inch pot and pluck the weaker seeding later. This is, so you’re sure to have some growth even if one seed fails to germinate. 

You can sow the seeds in biodegradable pots like peat or paper pots to reduce transplant shock to the plant.

Growing conditions

Light

• Nasturtiums thrive when planted in full sun (6 to 8 hours of direct sunlight daily)
• They can tolerate some shade (only 3 to 6 hours of sunlight daily)
• In warm climates, some shade is actually preferred

Soil

• Nasturtium flowers do well in free-draining, poor soil.
• They don’t need rich soil. In fact, it may be bad for them. If the soil is too rich, you may get more greenery and fewer flowers.
• Nasturtiums grow best in soils with a neutral pH. That’s when the soil level is between 6 and 8 pH.
• Nasturtium plants tolerate dry conditions but do best with moderate moisture.

Learn more here if Can You Use Potting Soil To Start Seeds

Water

• Nasturtiums typically require weekly watering. Water plants once a week in mild climates and twice a week in hot climates.
• They can survive moderate droughts. 
• If they’re planted in a greenhouse or a sunny vegetable plot, the water demand can increase. This is due to water drying from the heat and the use of the surrounding plants.

Temperature and Humidity

• Nasturtium prefers a daytime temperature of about 21 to 26 °Celsius (the 70s in Fahrenheit) 
• Nasturtium can survive light frost to average frost, but it can be easily damaged by freezing temperatures.
• Nasturtium does best at average humidity levels (30–50%)
• Nasturtium can struggle in extremely dry or extremely humid conditions

Fertilizer

Rich soil can cause the plant to put out more foliage than flowers, so organic gardeners rarely need to amend the soil before planting.

Chemical fertilizer use on nasturtium is not recommended if you plan on eating them.

If you have extremely poor soil conditions or you have other plants around that may need fertilizers, you can put organic fertilizer before planting.

Transplanting/ Repotting Nasturtium

Transplant your nasturtiums when they are mature. You can transplant seedlings, but they’re more vulnerable.

Also, make sure the risk of frost has passed. Planting mature nasturtiums also lower the risk of shock and damage from sudden late freezes or autumn frosts when compared to seedlings that may die in severe weather.

As mentioned above, they thrive in full sun, so choose a position to transfer them where they can get plenty of sunlight. 

If transferring to a bigger pot, you may add some pebbles for better draining. 

If you used a biodegradable flower pot, dig a hole in your planting location, cover the pot fully, but leave the plant exposed and set it. 

If you didn’t use a biodegradable pot, you need to remove the nasturtium from the soil completely. To do this, squish on the pot (if flexible) or take the whole soil out by loosening the edges first. 

Generally, you need to loosen up the soil and pull on the plant slowly until it’s free – carefully so as to not damage the roots and the growth.

Soil should crumble easily, but if your soil is too hard, you may try soaking it in water first, so it becomes softer. 

How to Care for Nasturtiums

Do not fertilize your nasturtium. As mentioned above, they will have abundant foliage but not many flowers.

Put mulch all around your nasturtium to keep the weeds down and help them keep their moisture better. 

Water them regularly. They stop their flower production fast if they get too dry.

Give them full sun but if you’re living in tropical weather, give them partial shade, especially afternoon shade.

Pay attention to pests as nasturtiums can attract them (which is why they’re amazing companion plants for vegetables).

For whitefly and aphid infestation, spray the nasturtium with a hose. The jet of water should be enough to blast those off.

For cabbage caterpillars, you can just pick those off by hand.

Aside from that, nasturtiums are pretty easy to care for.

Harvesting And Use

You can eat nasturtium flowers, leaves, and green unripe seed pods.

Harvest the nasturtium blossoms in the morning when they are plumped up with moisture. 

Cut the base of each blossom. They can have a bitter taste.

You can use the edible flowers and immature nasturtium leaves on salads and as an edible garnish on various dishes and cocktail drinks. 

You can also turn immature nasturtium leaves into pesto or mix them into smoothies.

You can also pickle the young buds.

Final Words

In conclusion, nasturtiums are beautiful flowers that grow easily from seeds. They are also edible and can take your dishes and drinks to the next level in taste and visuals.

Growing nasturtiums from seed are very easy and fun.

In a nutshell,

1) Start the seeds indoors

2) When plants are ready to go outside, transplant them into a free-draining soil

3) Water regularly

4) Enjoy!

We hope this article helped.

See you on another one!

You can also read our previous article about how to grow peony from seeds.