Growing vegetables without dirt?

[Hippie]

BACKSTORY: After global warming has caused the ice shelves of Greenland and the Poles to melt, the sea levels have risen over forty feet. London, New York and many other cities below current sea-level are under water almost completely. Since there are buildings taller than 40ft in many cities, I was thinking of having the people who fled up to the rooftops be survivors, and build boats (think, like, gondolas and rafts) to get to each other, and build platforms off from the tops of the buildings, to form a sort of community of survivors... but they need a way to eat and live.

So! I really need a way to have a group of survivors have the ability to be self-sufficient, and that means they have to have a reliable food source other than the fish that have poured in from the ocean (which aren't very numerous). Any ideas?

[Thuriel]

...One of the buildings had a rooftop greenhouse, and they propser by selling/bartering food to the other roofs? *shifty eyes*

[Hippie]

Well the whole thing is a group that is surviving together, instead of fighting and competing. But an already-established rooftop greenhouse is a good idea! :D

[Lord of Fools]

I answered your lj post, but those things I mentioned were tropical foods... I'm not sure of the scenario and I think that New York has a fairly humid summer as is, but what's the climate like, apart from being watery?

[Hippie]

I'm not quite sure... with the real science, it'd be cold, like going into an ice-age, but I don't want that... so I'm thinking like... normal NY weather? I don't really know what that is.

[Thuriel]

I'm going to ignore everything I know about the weather in New York (City) because so much of that would be totally different... but, um, in general, in this area (I'm in New England, but I'm also about an hour from the city) the weather is anything you can imagine it being. About the only thing I can think of that we don't get is that kind of really dry, hot summer you'd get in Arizona or something. Our hot summers are all really, really humid... typically. Again, we get pretty much everything around here. I remember summers over 100 degrees and winters in the single-digits. And it can change really quickly, too.

...If you can't tell, I'm mostly just rambling... I've lived here all my life; it's hard to describe our weather because I have nothing to compare it to.

[Hippie]

Sounds like Oregon. Don't like the weather? Wait five minutes, it'll change.

I'd call it 'temperate', though.

[Gene]

I'm going by the assumption that I'll be dead when this finally gets round to happening, because a tidal wave is definitely on my Top 10 list of Ways to Die. Anyway, maybe we'll have to cram millions of years of evolution into a few months and start living off solar power. WE SHALL CONQUER!

[Lord of Fools]

Hmm. See, most of the water-growing plants I know are ones from tropical climates. I guess maybe genetic engineering enhanced the ability of some of these things, like lotus lillies and mangroves, to resist severe cold weather and frost- which generally doesn't happen in the tropics- but given the propensity of water to freeze, water-dwelling plants are difficult.

I suppose they could all be kelp-farmers. Kelp's got a lot of nutrients and you can make all sorts of things from it, including chutney and sweeter jellies (agar). I'm assuming this is salt-water they're living with, right?

[MichaelB]

Has anyone thought about hydroponics? The plants grow in little plastic bags, fed with nutrient-rich water, compltely free of soil. Would they have the capacity for that?

Or would they have to evolve to be able to eat blue-green algae?

[AXJ]

^ I was going to recommend hydroponics, too.

[Lord of Fools]

Actually, apparently there was a village or city in China at some point that was under siege. So to stop themselves all dying of starvation, they set up a sort of collection and put all their urine in a big pot of some sort (or more than one I guess) and harvested the bacteria from that.

Yum yum.

[AXJ]

Whaaaaat?

Okay, I'm going to have nightmares about that now. Fucking EWW.

[Hippie]

I agree, AXJ. *ickyickyicky*

NO URINE BACTERIA HARVESTING PLZ, CHARACTERS.

I like the idea of hydroponics as well. I think Michael told me about it last night, and... no wait, I think it was Schu. >_> I totally can't remember, now I feel horrible. >_<

WHOEVER told me about hydroponics. Anyhow, they don't have to FIND a solution, it just has to be there. Mostly because this is like 3rd-5th gen. (haven't decided) of roof-dwellers at this point. And the system they use will have been in use for years.

[butterfly]

When I saw the title of this thread I got all excited because my mum has just managed to grow a pea on a pea plant that was grown on saturated cardboard, but it's not looking edible, and it's not really what you're looking for :(

[Lord of Fools]

I'm sorry. Know me long enough and you'll find out I'm a well of useless, often horrifying information.

[snooze]

Hrm...I have a book back home in Canada that might've been just the thing, but that doesn't help now, does it? I can't even remember the title or author, but it was this completely serious/significantly batty fellow who wanted to colonize the seas and the moon or something because the land was going to shit.

[Hippie]

If you're back in Canada before this year's NaNo, it'll still help me. :D Because that'd be perfect for me! It sounds like a fascinating read if nothing else. :D

[snooze]

I'll have a look in September.

[Le Grand Tango]

I think there are some semi-tall mountains kind of near NYC- maybe twice yearly they go off in boats to plant, and then harvest crops.
Mosses and lichen grow on concrete, some are edible.
Some things grow in sand, which might be easier to get then dirt.
butterfly- Growing things in wet cardboard? I have to try that.

[Thuriel]

^ The Catskills? I'd forgotten about them...

[KeinesV]

Hydroponics has been mentioned before, but here is some more data:

http://en.wikipedia.org/wiki/Hydroponics

http://en.wikipedia.org/wiki/Passive_hydroponics

http://en.wikipedia.org/wiki/Aquaponics

and aeroponics:

http://en.wikipedia.org/wiki/Aeroponics