This post contains affiliate links. As an Amazon Associate I earn from qualifying purchases. If you click a link and make a purchase, I may receive a small commission at no extra cost to you.
The best time to plant out nasturtiums is after the last spring frost has passed and the soil has warmed up a bit.
If you’re wondering when to plant out nasturtiums, the short answer is that these cheerful, sun-loving annuals are tender to cold and will not tolerate a hard freeze.
Planting them out too early can mean stunted growth or even death, so timing is everything.
In this post, we’ll dig into the ideal conditions for planting out nasturtiums, how to know when your garden is ready, and a few clever tricks to get a head start.
Let’s get those vibrant flowers and peppery leaves growing.
When Is It Safe To Plant Out Nasturtiums?
The safest time to plant out nasturtiums is generally two to three weeks after your average last frost date.
This is when daytime temperatures consistently stay above 60°F (15°C) and nighttime temps don’t dip below 50°F (10°C).
While nasturtiums are tough in many ways, their roots and leaves are surprisingly sensitive to cold soil.
So if you’re eager to plant out nasturtiums, resist the urge to rush them into the garden in early spring.
Watch Your Local Frost Dates
Your local frost date is your best friend when it comes to knowing when to plant out nasturtiums.
Check an online planting calendar or your local extension office for the exact date in your zone.
Once that date has passed, you can confidently plant out nasturtiums, but keep an eye on the forecast for any surprise cold snaps.
If a late frost is predicted after you’ve planted, simply cover them with a sheet or row cover overnight.
It’s a simple fix that lets you plant out nasturtiums a little earlier if you’re willing to play guardian.
Soil Temperature Matters More Than You Think
Air temperature is only half the story when you plant out nasturtiums.
The soil temperature is actually the bigger deciding factor for healthy root development.
Nasturtiums prefer soil that is at least 55°F (13°C) to germinate and grow strongly.
You can check this easily with a soil thermometer, but a simpler trick is to just press your hand into the soil for a minute.
If it feels comfortably warm rather than cold and damp, it’s likely a good time to plant out nasturtiums.
Cold, soggy soil can cause the seeds or young transplants to rot before they even get going.
Planting Out Nasturtiums From Seed vs. Transplants
When you decide to plant out nasturtiums, you have two main paths: direct sowing seeds or planting out young transplants you’ve started indoors.
Each method has its own timing sweet spot.
Direct Sowing Nasturtium Seeds Outdoors
Direct sowing is the most foolproof way to plant out nasturtiums because they hate root disturbance.
You can plant nasturtium seeds in the ground at the same time you’d transplant seedlings, right after the last frost.
Just poke the seeds about an inch deep and 10–12 inches apart.
They’ll germinate quickly once the soil warms up, and because you planted them directly, they won’t suffer from transplant shock.
If you want a continuous display, you can even sow a new batch every few weeks, though the first round is the most important.
Planting Out Potted Nasturtium Seedlings
If you started seeds indoors to get a jump on the season, you’ll need to plant out nasturtiums carefully.
Start by hardening them off for about seven to ten days.
Set them outside in a sheltered spot for an hour or two each day, gradually increasing their time outdoors.
After they’re fully hardened, choose a cloudy day or late afternoon to plant out nasturtiums.
This gives the roots a head start without the stress of intense midday sun.
Be gentle with the roots when removing them from their pots, as even slight damage can set them back.
Best Conditions For Planting Out Nasturtiums Successfully
Once you’ve nailed the timing for planting out nasturtiums, you also want to make sure the spot you choose is perfect.
These versatile plants aren’t fussy, but they do have a few clear preferences.
Sunlight Needs for Nasturtiums
Nasturtiums thrive in full sun, which means at least six hours of direct sunlight daily.
If you plant out nasturtiums in too much shade, you’ll get lots of lush foliage but very few flowers.
In very hot southern climates, a little afternoon shade is actually welcomed to prevent scorching.
But for most of us, more sun equals more vibrant blooms and peppery leaves.
Soil Quality and Drainage
Poor soil is actually better for flowering when it comes to nasturtiums.
If the soil is too rich or heavily fertilized, you’ll see an explosion of leaves and barely any blossoms.
Before you plant out nasturtiums, aim for average, well-drained soil.
They don’t need compost or extra feeding; in fact, they prefer lean conditions.
Just ensure the area doesn’t stay waterlogged after rain, as soggy roots will lead to rot.
Spacing and Companion Planting
Give each plant enough breathing room so air can circulate freely.
When you plant out nasturtiums, space them 10 to 12 inches apart for bush types and up to 18 inches for trailing varieties.
They make fantastic companions in the vegetable garden.
Plant out nasturtiums near brassicas, tomatoes, or cucumbers to help deter aphids and whiteflies.
Their bright flowers also attract beneficial pollinators and predatory insects that keep pests in check.
What Happens If You Plant Out Nasturtiums Too Early?
Timing really is everything when you plant out nasturtiums.
If you jump the gun and plant them out during a cold snap, several things can go wrong.
The leaves may turn yellow or develop brown, crispy edges from frost damage.
Growth will stall completely until the temperatures climb again.
Worse yet, prolonged cold, wet soil can cause the stems to rot at the base, which is often fatal.
So while it’s tempting to get them in the ground early, patience pays off big time with nasturtiums.
Even if your plants survive an early planting, they’ll often lag behind those planted at the right time.
So, When Should You Plant Out Nasturtiums?
You should plant out nasturtiums only after the danger of frost has fully passed and the soil has warmed to at least 55°F.
This is usually two to three weeks after your last expected frost date in spring.
By waiting for warm soil and stable nights, you give them the best possible start for a long season of color.
Whether you direct sow seeds or carefully transplant seedlings, the golden rule is to keep them cozy and warm.
Do that, and your nasturtiums will reward you with cascades of cheerful orange, yellow, and red blooms all summer long.
So check your local forecast, warm up your soil, and get ready to plant out nasturtiums at the perfect moment.
Happy gardening.