Growing Plants In Heat & Wind
July 7, 2010 10:12 AM   Subscribe

What can I plant on a hot, windy roof garden? My New York City apartment boasts a private roof deck. The problem: It gets constant sun all day long, and is the tallest building around, so it can get quite windy. Nearly everything I've planted has shriveled and died. What will work?

Before you link to them, I've seen the similar posts like this one, and they've helped, but my situation is rather more extreme, due to temperature and wind.

My wood deck is about 15'x7', and sits on top of the same black tar paper that covers the rest of the roof. There's no shade from other buildings, so this paper gets HOT over the course of a day, and while the deck itself is raised off the paper, plants can be exposed to pretty high heat. The aforementioned wind problem is also significant; while this is no skyscraper, and the wind isn't constant, I've found that delicate plants simply get blown to pieces when the wind gusts.

Another complication: This is New York, so while on a day like today, the roof deck is pulling temperatures in excess of 100 degrees, it will be exposed to plenty of cold and snow in the winter. I'd like plants that can survive both extremes.

My preference is for plants that will provide screening from the rest of the deck. I'd rather have something big and bushy than a delicate flower. I'd like perennials for screening, but I'm willing to plant the occasional annual for accents. And I'm not particularly interested in edible plants.

Here's what I've tried and how its fared:

> Acer saccharinum (silver maple)
about 5' tall in a big pot, it has survived for years, but not exactly prospered.

> Climbing Rose
grew nicely on a trellis, and stays green. it blossomed for the first time in 2 years this spring, but the flowers only lasted a week before they were scorched by the sun and died.

>Diervilla ionicera (northern bush honeysuckle)
only a sapling when planted, it grew pretty well for ~2 months, but then started to wither. not dead yet, but looking pretty weak.

> Viburnum dentatum
About 1' tall when potted, lasted about two weeks then withered and died.

> Daisies
Grew spindly stalks about 1.5' tall. Never blossomed or budded. Eventually died.

> Morning Glories
Grew spindly, climbing vines, which wound their way up the trellis i'd placed in the pot, but never blossomed.

> Crepe myrtle
Planted about 2 months ago as a 2' sapling. It hasn't grown very much, but it seems quite healthy and stable.

> Salvia gracias (creeping sage)
Planted about 2 months ago, seems to be prospering, and has grown quite a bit. But sage is rather small and while it provides a nice accent, I'm in the mood for bigger, more screening plants.

So, thoughts?
posted by eduke to Home & Garden (14 answers total) 1 user marked this as a favorite
Are you sure they're getting sufficient water? Heat + wind = dry soil.
posted by leotrotsky at 10:19 AM on July 7, 2010

Sedum. The right kinds are bomb-proof and used in several rooftop green projects.
posted by Cool Papa Bell at 10:19 AM on July 7, 2010

We've found that silver lace vine is pretty hardy and grows fast. It only lives a few seasons though.

Is there any chance you could cheaply build some sort of sunshade? Gazebos like this are really popular in Ontario and usually cost less than $200. They have holes in the base so you can screw them into the deck.
posted by bonobothegreat at 10:20 AM on July 7, 2010

My preference is for plants that will provide screening from the rest of the deck.

Whoops. Sedum won't work here. I recommend trellis + creeping fig.
posted by Cool Papa Bell at 10:21 AM on July 7, 2010

The biggest thing is to keep the soil moist. Check out what they're doing here.
posted by Threeway Handshake at 10:21 AM on July 7, 2010 [1 favorite]

posted by BobbyDigital at 10:45 AM on July 7, 2010

Best answer: I have the exact same situation as you - although I find winter wind is more of an issue for my hinoki cypress then the summer wind. I have a magnolia that does fine, and a big japanese cut-leaf maple that doesn't really thrive. Deciduous stuff is fine for winter. I wrap the evergreens in burlap to protect them.

For screening I use lots of annual grasses underplanted with some flowering things. All of my color comes from annuals.

Water Water Water. This time of year everything needs to get water AT LEAST everyday. And I'm contemplating switching to twice a day for some of the more exposed things.

Agree on the Sedum and other succulent-y type things - bombproof - in fact with this years heat the sedum variety I planted is taking over its container.

Also you seem to be buying plants not realizing what they are - for example your crepe myrtle is a tree - it shouldn't be growing very fast. That Viburnum is really an understory plant - not a full sun plant.

Morning Glories - spring and fall in NY - by mid summer they will be shot from the heat.
the Salvia is a good choice - but it is a perenniel variety so it won't grow supper fast.

In summation - use annuals not perennials for a lot of things - and assume you will have to change those from spring to summer and then back again in fall. Use grasses for screening. Maybe a bamboo in a container? Or a trellis with something growing on it? And water water water.
posted by JPD at 10:56 AM on July 7, 2010

Also what kind of containers do you have them in - you want something that will help retain moisture but won't crack during the winter when the soil freezes
posted by JPD at 11:04 AM on July 7, 2010

I grew marigolds and zinnias in an NYC tarpaper roof garden. They loved it (although they guzzled water). If you have a lot of space, there's okra.
posted by zvs at 1:07 PM on July 7, 2010

Best answer: Your main enemy on a hot, windy, roof deck is going to be the soil drying out. Unless you are watering your plants deeply every day, plants in containers in the conditions you describe are going to be incredibly stressed and struggling.

You have two solutions:

1) Increase your watering frequency or install drip irrigation

or 2) use xeric plants. You're in NY City, so you're in zone 7. However, you are planting in containers so it's probably much much safer to plant shrubs and perennials that are hardy to zone 5. High Country Gardens carries a large number of xeriscape shrubs and perennials.

Some suggestions: Caryopteris clandonensis, Cytisus purgans, Sand Cherry, and Rhus trilobata are all good sized shrubs that will probably thrive on your deck.
posted by lydhre at 2:15 PM on July 7, 2010

NYC is in zone 7 - but in reality because of the heat island effect winter hardiness is really not an issue even in containers.

Xeriscape stuff can be tricky as well because of the very high summer humidity.
posted by JPD at 2:56 PM on July 7, 2010

Think about a sun shade. I live in New Mexico, where not even tomatoes always do well in direct sun. You can see the white row cover material.

You may need to slice some holes in the cover to keep the wind from picking it up, but if it can survive the monsoon winds here it can survive NY.
posted by answergrape at 7:12 PM on July 7, 2010

Peppers absolutely LOVED my scorching, windy roof. While they are edible, which I know you mentioned isn't totally your scene, they come in a whole bunch of decorative varities aside from the standard stuff. Several of them are quite bushy and as a bonus have awesome tiny little colorful peppers to liven up the greenery.
posted by troublewithwolves at 9:27 PM on July 7, 2010

As stated, you might have a watering problem. If so, consider making an Earthtainer.
posted by mbarryf at 5:37 AM on July 8, 2010

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