Should You Soak Nasturtium Seeds Before Planting?

Sometimes seeds can be tricky to plant, especially if they’re very hard or large, as this can prevent them from germinating. Soaking seeds before you plant them in the soil is recommended, but it’s not effective or required for all types of seeds. So, if you have some nasturtium seeds you’d love to sow in the garden, should you soak them first? 

You should soak nasturtium seeds before planting because they’re hard and have a dry coating on them that reduces germination rates. This can make it difficult for water to enter the seed and force it out of its dormancy so that it sprouts.

In this article, I’ll explore everything you need to know about nasturtium seeds, how to soak them, and how to plant them so their charming flowers can brighten up your garden within 35-50 days

Why Nasturtium Seeds Need To Be Soaked Before Planting

Nasturtium seeds need to be soaked in water before they’re planted in the garden so that water can soften their hard coatings while also penetrating them. 

By giving your seeds water, you mimic the natural conditions that the seeds would be experiencing if they were already in the soil, such as moisture in the form of rain. Since seeds can determine the temperature and moisture level in their surrounding environment and use this as an indication of when to sprout, if you mimic the conditions that encourage their growth, this will help them germinate quicker

Another benefit of soaking seeds in water is that the water will remove any growth inhibitors or substances in the seeds that can prevent them from sprouting. 

If you don’t soak hard seeds, their chances of a successful germination will be significantly reduced. Alternatively, they simply won’t grow at all. 

How To Soak and Prepare Nasturtium Seeds Before Planting

When you’re ready to soak your nasturtium seeds, you might wonder how to go about it. Here are some essential tips to bear in mind. 

  1. Scarify the seeds before soaking them. Before you soak your seeds, you should scarify them to ensure greater germination rates. To do this, scrape a side of the seed with a metal file so that you can see inside it. Doing so ensures that the seed will absorb water through this cut. 
  2. Use warm tap water. After scarifying the seeds, fill a bowl with warm water from the tap, and add your seeds to them. Avoid using boiling water, as this is too harsh and can cook delicate seeds. 
  3. Leave the seeds in the water for eight hours. Since nasturtium seeds are large and tough (they resemble small brains!), they should be left in the water for several hours. However, avoid over-soaking them. If you leave the seeds in for too long, such as the whole day, you risk them rotting. You should leave nasturtium seeds to soak for no longer than eight hours, as Napa Master Gardener Column reports. 
  4. After eight hours, you’re ready to plant the seeds. When the seeds have soaked enough, drain the water, and plant the seeds. 

How To Plant Nasturtium Seeds After Soaking Them

Once you’ve soaked the nasturtium seeds, make sure you don’t leave them to dry somewhere. You have to sow them immediately because if they’re exposed to the air, this will cause them to ferment. Once you’ve sown your seeds, they should sprout within two weeks. 

However, if you don’t soak the seeds, you can keep them longer until you have the right conditions to plant your seeds. Read my article to see how long nasturtium seeds last: How Long Do Nasturtium Seeds Usually Last?

Here are some other tips to ensure success when you’re ready to plant your nasturtium seeds, whether you’re planting them indoors or outdoors. 

How To Plant Nasturtium Seeds Indoors

You should start your nasturtium seeds indoors around four to six weeks before the last spring frost has occurred. This will ensure that the transplants will be ready to be placed in containers or in the garden when the temperature is warm. 

However, note that nasturtiums have taproots and don’t want to have their roots disturbed, which is what happens during their transplantation. This is why it’s always best to directly sow their seeds straight into the soil wherever you want them to grow in the garden. 

If you still want to plant your nasturtium seeds indoors, you should plant them in peat pots. This will make them easier to transplant in the garden later, as these pots prevent root disturbance because you can plant the peat pots straight into the ground. 

I’d recommend purchasing HOMENOTE Peat Pots, available from Amazon. They’re biodegradable pots equipped with drainage holes. They come in a 60-pack of peat pots that are textured, which makes them easy to remove from each other when you want to use them, preventing sticking.

Here are some other essential tips for growing seeds indoors. 

  • Put the potting mix in a pot or container. Make sure the pot or container has drainage holes to remove excess water. 
  • Add warm soil to the pot. If you’re adding soil from the garden to your pot, you should let it stay in a warm area of the garden for a day or two before you use it. This will ensure the seeds are placed in the right conditions to sprout. 
  • Maintain a soil temperature of 70°F (21°C). The seeds will germinate best when they’re planted in warm soil. 
  • Give the seeds enough room. Put one nasturtium seed in each pot, or place them two inches (5 cm) apart. This ensures that the nasturtium plants will have enough space, especially because their seeds are large. Plant the seeds about one inch (2.5 cm) deep in the pot. 
  • Keep the seeds in darkness during their germination. Then place them in a bright, warm area until you’re ready to plant them outdoors. If you live in a region that experiences lots of overcast weather, you should invest in grow lights for your seeds.
  • Water the seeds regularly. Once your nasturtium plants start to grow, make sure you water them regularly. They require deep soaking and about one inch (2.5 cm) of water per week.
  • Give the seeds fish emulsion.Dilute fish emulsion and feed it to the plants once in a while to replace nutrients that can be washed away from watering them. I recommend purchasing Liquinox 5-1-1 Fish Fertilizer, available from Amazon. It’s safe and doesn’t burn, and can be used on flowers, lawns, trees, and vegetables. 
  • Choose clay or stone containers. If you’re growing seeds in containers, make sure they’re made of clay or natural stone with enough drainage. A good tip is to add a layer of pebbles to the bottom of the container so that you enhance the pot’s drainage capacity, as The Spruce reports. 

How To Plant Nasturtium Seeds Outdoors

When planting nasturtium seeds in the garden, make sure you first prepare the soil. Here’s how to do that (along with other essential planting tips to follow): 

  1. Ensure the soil is well-draining and gets a minimum of six hours of light per day. 
  2. Avoid applying fertilizer to the soil, as nasturtiums don’t want to be planted in rich soil. 
  3. Work two inches (5 cm) of compost into the soil. This will enhance drainage and improve the quality of the soil
  4. Plant your nasturtium seeds one inch (2.5 cm) deep, and ensure they’re about three or so inches (8 cm) apart from each other. If you have a large plant variety, keep the seeds about 24 inches (60 cm) apart. 
  5. Keep the top six inches (15 cm) of the soil moist so that the seeds will have enough moisture to sprout. 
  6. When they sprout, ensure that you water your nasturtiums when the soil becomes dry, so aim to water them a few times every week. Stick your finger into the soil to test if it’s dry and therefore requires water. 
  7. When you can see the seeds have sprouted, thin the plants. You want them to have about eight inches (15 cm) of space all around them so that they have enough room to grow. You can thin the plants by cutting any weak or crowded seedlings. 
  8. Once you can see the nasturtium seedlings are growing, it’s a good idea to label them as you might mistake them for weeds
  9. When the nasturtium plants reach a height of approximately seven inches (18cm), you should provide them with support in the form of a stake or trellis, as the University of Florida reports. 
  10. Water your nasturtium plants around their roots instead of from above the plant, as this will prevent too much moisture from getting on the plant and causing mold or fungal diseases. 


If you’re planting nasturtium seeds in your home, whether indoors or in the garden, it’s always a good idea to soak them first. Soaking these hard, tough seeds before planting them will boost their chances of germination success. Soaking seeds provides many benefits, such as: 

  • Softening the exterior coating of seeds 
  • Ensuring that the seeds can absorb moisture to speed up their growth  
  • Mimicking natural conditions, such as rain, to acclimatize the seeds to their environment

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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