Blue Fox Garden: Dangerous Gardens, on Garden Designers Roundtable

The topic for this month's Garden Designers Roundtable is “Dangerous Gardens” and I've been invited to guest post, what an honor! Since dangerous gardening is my passion I do have a few things to say on the matter, I’m sure you’re not surprised.

Agave utahensis

I believe a truly dangerous garden includes multiple layers of perilous essentials…..first up is monetary danger; any gardener that hopes to build a "Dangerous Garden" must be able to throw financial caution to the wind at a moment’s notice and buy a trunk-load of plants whenever the opportunity arises.

the trunk of my car after a fabulous day of plant shopping with friends...

The word “budget” has no place in this style of gardening. Of course you won’t want to spend your actual mortgage payment on plants, that would be fool-hardy…you need a plot of land on which to put your plants after all! But if your goal is to have a spectacular dangerous garden there’s nothing wrong with putting off investing for retirement, or even that new roof you should be saving for.

Secondly, what is more dangerous than the possibility of death? It’s very important for any dangerous garden to have several poisonous and carnivorous plants.

carnivorous Sarracenia

Take the genus Euphorbia, it’s a garden mainstay in many parts of the world, yet lurking just below the surface is a caustic, poisonous milky sap. This sap has the potential to not only irritate any skin that it comes in contact with, but also cause permanent blindness. Use care when handling!

Eryngium agavifolium (left) Euphorbia excalibur (right)

Next, forget the commonly accepted parameters of your climate zone, what fun is there in playing is safe? Embrace the danger; push that zone, after all how do you really know that plant isn't hardy in your garden until you've killed, it at least twice?

unknown Cylindropuntia from my in-laws in New Mexico,
is it hardy in my garden? Only time (and the upcoming winter) will tell...

Hybrid Echinocereus triglochidiatus v. gonacanthus (left), Yucca rostrata (right)...the Echinocereusis
hardy to temperatures colder than it will experience in my garden, but can it handle the winter wet?

But the most important (and my favorite) component for a truly "Dangerous Garden?" The spikes!

Agave gentryi 'Jaws'

Whether they be the obvious spikes found on Yucca, Agaves and Cactus or the more unexpected tips of Mahonia, Phormium and Poncirus nothing beats a few carefully chosen spikes to really make a garden memorable!

Mahonia x media 'Charity'

Seriously though, beyond any other type of plant I think it’s the spiky ones that cause the average gardener pause. I've been told that since they look so different from “other plants” they are intimidating. As though anyone can grow a daisy but it takes special knowledge to grow an Opuntia or Agave.

Blooming Opunita humifusa with Cotinus 'Royal Purple'

Actually, in some ways they’re right; it all depends on where you’re gardening. Many of the best spikes are dry sun-loving plants; you've got to make sure the soil around these plants will allow water to flow away. Here in winter-rainy Portland I make sure to work in enough grit (pumice, small gravel or chicken grit) with the surrounding native soil that it’s impossible to make a ball of soil in my fist without it breaking apart when I open my hand. Secondly I mound up the area around the plant so it sits on a mini hill, to keep the rain streaming away. Also I tilt the plant a bit, so that water can’t collect in the crown, which can be the kiss of death for an Agave. Finally a little gravel mulch helps keep the plants clean and allows you to cover the neck of the plant with a material that lets it stay drier than if you brought the soil all the way up.

Agaves in my garden planted on a small hill and tilted slightly for rain run-off

Another factor that I believe intimidates people from planting spiky plants is the question of where to plant them? You can’t just plop a cactus down in the middle of a perennial bed; you need to have a designated area, a rock garden!

Or so the thinking used to be. Thankfully that’s changing and more and more people are realizing how beautiful a few spikes can be mixed in with the rest of the garden.

Agave parryi 'J.C. Raulston' with Ceanothus gloriosa ‘Pt Reyes’

In fact their pointy tips and dangerous look can be the perfect counterpoint to a soft billowing grass or a big leaf.

Puya coerulea in the center surrounded by blooming Grevillea molonglo, with a tiny Agave ovatifolia
in the foreground (left) and Nassella tenuissima (right)