Why We Changed Our Minds on Irrigation

For a long time, we were pretty staunchly against irrigation.

As a landscape practice founded on “restoring ecosystems while making beautiful places for people,” putting pipes and plastic and who-knows-what-else into the ground to water a plant has always seemed like a bad idea. It felt like solving one problem by creating countless more: more waste, more products, more infrastructure, more maintenance, more labor, more transport, more…everything. Again, antithetical to what we’re doing here at Viridian. Our work primarily uses native plants adapted to this climate and less resource intensive. “Less is More” isn’t just for architects.

But…

(I’m sure you knew there was a “but” coming)

But, as we’ve grown older and wiser and as we’ve watched the world spiral toward environmental cataclysm, our thinking has evolved. We no longer believe skipping irrigation automatically makes us the good guys. Sometimes it's the more responsible thing to do.

The Case for Irrigation

For us, it comes down to one thing: establishment.

If you plant a native meadow or a garden or a restoration area and then it gets hit by one of these brutally hot summers with no support at all, what exactly do you think is going to happen? Withering. Withering will happen. Dying too. We see it a lot more than we used to, unfortunately. The new plants may be native, they may be carefully selected for a specific micro-ecosystem, and they may be tough little generalists, but they’re still vulnerable little guys trying to get rooted in a world that's getting hotter and less predictable every year.

Those first few years in a plant's life are enormously important. Plants are adjusting to unfamiliar soil, sun, and competition. Their roots need time to develop. The whole landscape needs time to become what we designed it to be. Irrigation buys that time. An appropriately scaled irrigation system can ensure that a new landscape becomes a resilient landscape.

Obviously, it's never our goal to create a landscape that depends on irrigation forever. Quite the opposite. We want landscapes that need less from us — eventually nothing. But sometimes, to get there, they need real support at the beginning.

We saw this clearly in conversations with our collaborators at the Nantucket Conservation Foundation, who are about as serious about ecology as anyone we know. Even there, in restoration work, the answer was not “never water.” It was more nuanced. Temporary irrigation is occasionally needed during the first year or two, especially on a harsh site like Nantucket or in a hot August, when even two-year-old plants are under stress. Our work at the Philadelphia Zoo is another instance where installing irrigation made sense. There, it was due to the constant crowds and lack of staff capacity for establishment watering.

Climate Change (Again)

Our shifting stance on irrigation reflects yet another instance where climate change makes the old rules harder to follow. Yes, ecosystems have always changed, but the speed of change now is the problem. The conditions we're designing for now aren’t the same ones we designed for just ten years ago. Summers are hotter, storms are less predictable, and planting zones are drifting north. So we've adapted.

We adapted first with plant choices, using plants from more southern zones, for example, or generalists.  But even those can still need a boost in the first three years. So, then we became more realistic. We're no longer asking, “is irrigation good or bad?” We're now asking: what does this landscape need in order to thrive with the least waste over time?

Sometimes the answer is nothing. We love that. Sometimes the answer is a drip irrigation line. We’ve accepted that. Sometimes it will be better soil preparation, a different plant strategy, or a maintenance plan that's appropriate for the design (and actually followed). Usually, it's a combination of those things, figured out site by site.

The Cost of Failure

We can all agree that, yes, putting more plastic into the ground isn’t great. But replacing a failed landscape isn’t really great either. That failure has a cost that’s easy to look past – an ecological cost as well as a financial one. Replacing a failed landscape means growing/buying/shipping replacement plants. It means crews coming back on site. It means more soil, more mulch, more trucking, more labor, more carbon, more money. Now we’re back to more again.

Every site and situation is different. But if a drip irrigation line helps a landscape establish and thrive, that may be the more responsible choice, even if it makes us a little uncomfortable. We do the best with what we’re given.  It’s like I told an engineer when he asked me which tree was best: “A live one.”