How And When To Plant Nasturtium Seeds

You should plant nasturtium seeds in the spring after the last frost has passed, and you can also start them indoors a few weeks earlier to get a head start on the season.
 
Knowing how and when to plant nasturtium seeds is one of the easiest gardening tasks you’ll ever tackle, because these vibrant, edible flowers are incredibly forgiving and low-maintenance.
 
If you’re wondering how to plant nasturtium seeds for the best results, the secret lies in understanding their love for cool soil and their dislike for root disturbance.
 
In this post, we’ll walk you through the ideal timing for planting nasturtium seeds, the step-by-step method for sowing them directly in your garden, and a few tricks for starting them indoors.
 
We’ll also cover common mistakes to avoid so your nasturtiums thrive and bloom from early summer all the way to the first fall frost.
 
Let’s dig into the details of when and how to plant nasturtium seeds.
 

When to Plant Nasturtium Seeds: Timing It Right

The best time to plant nasturtium seeds is in the spring, once the danger of frost has completely passed and the soil has warmed to at least 55°F (13°C).
 
Nasturtiums are tender annuals, which means they simply cannot tolerate freezing temperatures, so planting nasturtium seeds too early in cold, wet soil will cause them to rot before they ever sprout.
 
If you live in a region with a short growing season, you might be tempted to plant nasturtium seeds as soon as the snow melts, but patience is key here.
 
Wait until nighttime temperatures consistently stay above 50°F (10°C) because that’s your signal that the soil is warm enough for reliable germination.
 
For most gardeners, this lands somewhere between late April and late May, depending on your USDA hardiness zone.
 
If you’re eager to get a jump on the season, you can start nasturtium seeds indoors about four to six weeks before your last expected frost date.
 
However, when you plant nasturtium seeds indoors, you must use biodegradable pots like peat pots because their roots are extremely sensitive to transplant shock.
 
Another option is to plant nasturtium seeds in fall if you live in a mild winter climate (zones 9-11), where they will happily overwinter and bloom early the following spring.
 
But for the vast majority of gardeners, spring is the golden window for planting nasturtium seeds directly where you want them to grow.
 

1. Direct Sowing After the Last Frost

Direct sowing is by far the most foolproof method for planting nasturtium seeds because it eliminates the risk of damaging their delicate taproots.
 
Once your soil is workable and frost is no longer a threat, simply press the seeds about half an inch to one inch deep into the earth.
 
Space each seed about 10 to 12 inches apart if you’re growing the trailing varieties, or about 8 inches apart for the compact bush types.
 
Water the area gently after planting nasturtium seeds, and keep the soil consistently moist but not soggy while you wait for sprouts.
 
Germination usually takes about 7 to 14 days when soil temperatures are in that sweet spot of 60-70°F (15-21°C).
 
One of the best things about direct sowing is that nasturtiums will settle in without any transplant stress and reward you with stronger, more vigorous plants.
 

2. Starting Indoors for an Early Bloom

If you decide to start nasturtium seeds indoors to enjoy flowers earlier, you’ll need to be extra careful during the transplanting process.
 
Use peat pots or paper pots that can be planted directly into the ground, because disturbing the roots of nasturtiums often leads to stunted growth or plant death.
 
Plant two seeds per pot, pushing them just beneath the surface of your seed-starting mix.
 
Keep the pots in a warm spot with plenty of sunlight or under a grow light, and maintain even moisture until you see those first round leaves appear.
 
About a week before you plan to move them outside, harden off the seedlings by bringing them outdoors for a few hours each day to acclimate them to the elements.
 
When you plant nasturtium seeds indoors, you gain about three to four weeks of extra growing time, which can make a big difference in short-summer regions.
 

How to Plant Nasturtium Seeds: Step-by-Step Guide

Learning how to plant nasturtium seeds properly involves more than just picking a date, because soil prep, spacing, and watering all play a role in your success.
 
Here’s a simple, friendly walkthrough to get those cheerful orange, yellow, and red blooms popping up in your garden.
 

1. Choose a Sunny or Partially Shaded Spot

Nasturtiums thrive in full sun, which means at least six hours of direct sunlight each day, but they’ll tolerate light afternoon shade in hot climates.
 
Choose a location with well-draining soil because soggy roots are one of the quickest ways to kill these otherwise tough plants.
 
Interestingly, nasturtiums actually prefer poor, lean soil over rich, fertile ground, so skip the compost and fertilizer when planting nasturtium seeds.
 
Too much nitrogen will give you a mountain of leaves but very few flowers, which is the opposite of what you want from these edible beauties.
 

2. Scarify and Soak the Seeds

Nasturtium seeds have a tough outer coat, so giving them a little help before planting nasturtium seeds can speed up germination dramatically.
 
You can gently nick the seed coat with a nail file or a sharp knife, being careful not to damage the inner kernel.
 
Alternatively, soak the seeds in warm water overnight (about 12 hours) to soften that outer shell and trigger moisture uptake.
 
This simple step isn’t strictly necessary, but it often reduces germination time by several days and improves your overall success rate.
 
After soaking, you’ll notice the seeds swell up slightly, which is a great sign that they’re ready to sprout.
 

3. Water Wisely and Thin Seedlings

Once you’ve sown your nasturtium seeds, water them thoroughly right away to settle the soil around them.
 
After that, keep the soil lightly moist until seedlings emerge, but avoid overwatering because those seeds can rot if left in standing water.
 
When your seedlings have their first set of true leaves, thin them out by removing the weaker ones so the strongest plants have room to spread.
 
If you’re growing climbing varieties, make sure to place a trellis or fence nearby because they’ll happily scramble up any vertical support.
 
For bush types, you can let them fill in as a lovely ground cover or edging plant along your garden beds.
 

Common Mistakes When Planting Nasturtium Seeds

Even though nasturtiums are easygoing, a few common errors can prevent your planting nasturtium seeds efforts from paying off.
 
Avoid these pitfalls, and you’ll be rewarded with an explosion of color all summer long.
 

1. Planting Too Early in Cold Soil

The biggest mistake gardeners make is planting nasturtium seeds while the soil is still too cold and wet.
 
Cold soil causes the seeds to sit dormant, and if it stays cold for too long, they’ll eventually rot or become a snack for hungry pests.
 
Always test your soil temperature with a simple thermometer before sowing, and if it’s below 55°F (13°C), just wait another week or two.
 
Patience really is your best friend when it comes to the timing of planting nasturtium seeds.
 

2. Over-Fertilizing the Soil

As we mentioned, rich soil is actually a detriment to nasturtiums because it encourages lush foliage at the expense of flowers.
 
If you’ve heavily amended your beds with manure or synthetic fertilizer, your nasturtiums will look gorgeous and leafy but produce almost no blooms.
 
Stick to planting nasturtium seeds in average, even slightly sandy soil, and they’ll thank you with an abundance of colorful blossoms.
 

3. Transplanting Without Peat Pots

If you’re coming from indoors, never yank a nasturtium seedling out of a plastic tray by its delicate stem.
 
Their roots are extremely sensitive, and any disturbance can set them back for weeks or even kill them outright.
 
Always use biodegradable pots that allow you to plant the entire pot directly into the ground, and don’t worry, the pot will break down naturally.
 
This is the single most important tip for anyone starting nasturtium seeds indoors.
 

So, How and When to Plant Nasturtium Seeds?

You should plant nasturtium seeds in the spring after the last frost has passed, and you can also start them indoors a few weeks earlier for an early bloom.
 
The best approach is to direct sow them in poor, well-draining soil with full sun, after scarifying and soaking the seeds overnight.
 
When you plant nasturtium seeds directly in the garden, space them properly, water gently, and avoid rich fertilizers for the best flower production.
 
If you start them indoors, always use peat pots to protect their sensitive roots during transplanting.
 
Now that you know how and when to plant nasturtium seeds, you’re ready to grow a stunning, edible display that pollinators will absolutely adore.
 
Happy gardening, and enjoy those vibrant blooms all season long.