As the heat dome continues to blast through the US, many are battling the constant struggle to keep plants hydrated and healthy. But the real trick to having a thriving garden in the midst of a heatwave is choosing drought-tolerant, heat-loving plants that won't wilt as soon as the sun hits.
Enter, eryngium. Also known as sea holly, this blue (or white) thistle-like plant is my go-to for a fuss-free summer perennial. Perfect for growing in containers (especially compact varieties like these eryngium 'Blue Hobbit' seeds on Amazon), it's a gorgeous plant to have on your patio to keep your hosting space looking bright and lively even in scorching temperatures.
The best part is, it really doesn't need much attention – sea holly doesn't need pruning until much later in the year, nor does it demand fertilizer. Not to mention, I find bees and butterflies buzzing around my eryngium all summer long. Here, I explain more about why it's my top pick of a drought-tolerant perennial to grow on your patio in a heatwave.
Suited to Drought
Eryngium is found in a few varying habitats across Europe, the Mediterranean, Asia, and the Americas. It grows everywhere from grasslands to rocky slopes, and even coastal dunes, all of which have little rainfall and well-draining soil.
Once established, they're super drought-tolerant. This is thanks to their deep taproot accessing moisture deeper in the ground. Even in containers, they can cope with drier conditions better than other plants, making them much less susceptible to heat stress.
In fact, excessively wet soil is likely to cause root rot and the collapse of sea holly, so it thrives in the well-draining environment of containers.
They likewise thrive in full sun, ideally needing 6-8 hours of direct sun daily. The more sun exposure, the more vibrant their iconic blue or silvery white is. Plus, they thrive in poor soil types, including sandy soil, so fertilizer isn't necessary to get a big cluster of thistles.
A 50:50 mix of this well-draining Miracle Gro potting mix from Walmart and this horticultural grit from Amazon will work perfectly for eryngium.
So, for a sun-soaked patio in a heatwave, eryngium will reliably keep your space looking fresh and bright, without much effort.
Loves Growing in Pots
As mentioned, eryngium is suited to container garden growing because it loves well-draining soil and doesn't mind when nutrients deplete.
A planter with a drainage hole is essential, and because sea holly has a deep taproot, it's best to choose a planter at least 12" deep. This large white planter from Wayfair would work well.
Position your eryngium pot in a full sun corner. At a minimum, it will need 4-5 hours of sun exposure, so it can adapt to partial shade.
You should water regularly when you first plant your eryngium, but it will need less watering once established in following years. You can use a soil moisture meter (like this from Amazon) to check when the whole pot has dried out before watering again.
And once winter comes around, it's best to move your container to a sheltered spot. I like to wrap mine with burlap (like this from Amazon) to protect these plants from frost.
Best Eryngium Varieties to Try
There are so many different types of eryngium, but some are better suited to container growing if you're planning to position it on your patio.
I have a 'Blue Hobbit' eryngium, pictured above (you can find seeds on Amazon). It's a compact variety that produces multiple clusters of blooms in summer. It reaches just 12-20" in height, ideal for pots.
If you have larger containers to fill and you want something architectural, eryngium 'Big Blue' is a good option (and it's available at Plant Addicts). It produces tall 24-36" flower spikes.
For something a little bit different, opt for eryngium 'White Glitter' (you can find seeds available at Walmart), which has silver-white blooms. It also reaches a height of 24-36" tall. Full sun will bring out a shimmer to its bracts, hence its name.
A US native eryngium for pots is the white 'Rattlesnake Master' (you can find seeds on Amazon). It's another tall variety, reaching up to 48-60", so it definitely makes a statement piece and requires a large planter. It has much more compact bracts than other types of sea holly, giving the flowerheads a more spherical silhouette
What to Shop
'Blue Glitter' sea holly reaches a mature height of 2-3ft. It's suited to USDA zones 5-8.
This soil moisture meter can help you avoid watering mistakes. Simply insert the probe and it will identify how wet the soil is.
This large planter has a beautiful patina finish. It measures 13.8" in height, ideal for eryngiums.
If you want to boost your yard's resilience to extreme weather even more, consider adding more native plants for a drought-tolerant pollinator garden to your yard.
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