So, I have this funny idea that I want to grow a deciduous vine up from my gutters onto the roof. The goal would be to shade the roof in the summer, but die back to allow warming in the winter. I imagine I would have to have some amount of growing media in the gutter, probably expanded clay, and I would need a drip line to keep water on them in the long dry spells we have here in Cheyenne. I was thinking of using Maypop, counting on the south facing nature of the gutters and close proximity to the house to keep them zone 5 warm in our zone 4 climate.

So, how dumb is this idea?

You really want those gutters as a way to channel excess water off the roof safely. Much better to install a rainwater catchment system, plant a climber near the overflow (so it can help use the water you can't store) and then train that climber back up over your roof, doing the same job as you propose. But watch out, you'll need to clear out all the leaves or else you'll end up with plants in your gutters for sure!

So, how dumb is this idea?
.....
Really, really dumb. As pointed out already, your gutters serve a purpose.

I started laughing and shared the idea immediately.

So residue in the gutters is currently not a problem. We have no trees large enough to get leaves in the gutters, and likely never will. I really don't see water evacuation as a problem, but if it was, the locations I'd be doing this on have either concrete below the gutters, or, a lower level of roof, so over flowing the top of the gutters wouldn't be an epic house melting problem.

The biggest problem I could foresee would be using a plant like English ivy which could do damage to the roof. Or a clog in the gutter, maybe a buildup of organic matter.

I like the idea of a parallel or secondary gutter dedicated to this purpose probably with a line to get water straight from the main gutter,suplemented with water from a drip or float.

So the next question then focuses on the vegitarion type. I'd think a vine would work best. I was considering maypop for its perennial roots, flowers and fruit. But I could see using beans too. Any suggestions?

I think a "rain garden" - garden at the outflow of the gutter makes much more sense than a gutter garden, because of the challenge of attaching a strong enough structure to the house to support the weight of wet soil and plants, and the tremendous temperature fluctuations in the exposed gutter garden versus the dirt garden.

http://www.lowimpactdevelopment.org/raingarden_design/whatisaraingarden.htm

What type of roofing do you have? I think most vines would quickly destroy a asphalt style roof. Even for something more durable, I still think you'd be better served by adding a trellis that rests a few inches over the actual roof surface. That would improve airflow for the vine, reducing disease; and raise the climbing structures of the vine (many of which can get destructive) away from the actual structure of the house.

Another problem that I haven't seen here is the root mass. How much room does a vine need for it's roots to support that mass of growing leaves, vines, flower, and fruit? Gutters tend to be fairly small. The only plants I've seen grown successfully in them are the kinds that need very little root space (lettuces, strawberries, succulents) and they still require daily watering.

If you can stand to wait for the time it takes to grow that big, there are vines that are traditionally used in this fashion on more open spaces. I would still want the trellis laid on the roof, but off the top of my head, both grapes and hardy kiwi are known to grow massive enough to cover large trees.

I'm intrigued.

I don't think I'd want something growing directly in the gutter, but what if you were to add what would amount to extra downspouts (two, three?) along the length of the gutter. Keep the original downspout clear so that water could flow down and away from the house, but add a few other downspouts along the length of the gutter.

But you wouldn't run these new downspouts to the ground --- just run them down a foot or so, and then cap them. Drill a couple of holes in the bottom on the cap so that they will still drain slowly when water fills them, then fill will potting soil and plant in these "dummy downspouts". I would make sure that the level of the dirt in the dummy downspouts is lower than the gutter, so water can still flow along the length of the gutter and overflow out to the real downspout.

So . . . when it rains, the water will flow down the roof into the gutter, and the first places the water will collect is the dummy downspouts, where your shade vines would be growing. Once these are filled, the water will continue to flow down the gutter and out the original downspout to the ground. Now you get the best of all worlds -- rainwater collection for your shade vines, and you are still moving the water away from the roof and house.

In dry times, you'd just spray some water up onto the roof and it would naturally flow to the low spots along the gutter -- the dummy downspouts where your vines are planted.

But the bigger the vine, the larger you would need those dummy downspout planters to be --- large vines are very thirsty. I would imagine that they could get quite heavy. I'd want to plant something annual, rather than a big vine like wisteria because eventually the roots of that vine would start to tear things up.

Most vines that I'm familiar with can become quite aggressive.
I wouldn't want them clinging to my roof, considering their aggressive nature.

I have seen vines damage brick homes. What could they do to flimsy shingles?
They would probably begin growing under the shingles rather quickly, destroying the integrity of the roof. Water would begin to be held under the shingles, further compromising the integrity of the roof.

I see this as a Win/Win for the vine, but a Lose/Lose for the homeowner.

It's asphalt shingle. I would definitely use a standoff trellis for all the reasons you mentioned Casie. Probably a galvanized, welded wire fence with 2-3 inches (?) of air gap. Weight on the gutter would be reduced by using an expanded clay medium, and by reducing root mass and plant stress with constant access to water, but then we're basically talking hydroponic growing, and I don't want to mess with maintaining nutrient levels and such, and I don't have a good way to incorporate aquaponics, especially on the higher roofs.

However, if I could get a vine with perennial branches, then I could have the vines grow from planter boxes, with soil from the ground or lower roof level and then grow up to the roof level. With maypop or beans the yearly die back would prevent this, but kiwi, or maybe grape, could make the distance over a few deasins. Pruning would be an issue though, and removing leaves in the fall would be difficult with the standoff trellis.

Thoughts?

I'm personally not seeing how you'll get enough vigorous growth from a plant in a container/gutter to effectively cover the roof. Why not just grow it in the ground where it has a much better chance of success? Why insist on a difficult course of action likely to fail?

Okay, I'm stretching a little here, but I have a very vague memory of seeing a roof top trellis that was hinged to lift out of the way when painting and roof maintenance needed to be done. It was on a rather pricey home so I don't know how difficult it was to actually achieve. (Doesn't it seem like some problems shrink when you have money to throw at them )

With Grape vines, you might be able to prune back to the roof eaves each year and just allow the yearly growth onto the roof. Keep a main trunk that is trained to run along the eaves rather than over the roof. Look at some pictures of vineyards before and after pruning. Those are some crazy vigorous growers. I'm not sure about the kiwis. I hear stories but haven't actually seen them grow in person.

How about vines trailing down? Maybe cucumbers? It'd put a lot of weight on the gutters though.

For vines, how about hops?
As for the weight, I don't see that as much of an issue, unless the house itself is decrepit. Anchor in the studs or in the brick.
But I would prefer a ground based approach myself, because I would want to shade the walls of the structure as much as the roof.
More than the roof actually, since my first floor is 12" of brick....
If there is to be any pumped irrigation at all, perhaps evaporative cooling of the the roof is the way to go.

Something I have been considering with gutters is running a slotted 1 1/2 to 2" pipe along the bottom as a reservoir, and fill the rest with wicking medium.
Then, discharge greywater through this setup. I was thinking some kind of trailing vine, or even comfrey if I was willing to run multiple gutters in stacks.
The thing is, grey water is more regular than rain,and when the weather cools, I would rerouted the grey water back to the city sewage,thus withdrawing nutrition and moisture and encouraging dormancy.