I have a number of questions on hygiene and general gardening practice in a
roof garden.

I live in an apartment with a large roof terrace where everything is in pots
& troughs. There are about 8 troughs (1500mm x 450 mm x 400 mm each) about 6
pots half that size, plus smaller herb pots scattered around.

Creating an environmentally friendly roof garden poses a number of
difficulties and questions:

--

I am wondering if it will be a good idea to get a composting bin. I am
advised that while the soil from these is good for gardens, it will be too
compact if used on its own in pots. I would therefore need to use only a
little soil from the compost bin and mix it in from time to time with the
potting mix in my pots. I'm told on the other hand that plants love the
liquid which comes from the collecting tray in the compost bin.

Q1. At the moment I don't know whether to get one of these bins, there is no
decent shade yet on the balcony (worms will die) and I wonder if I will be
able to use up all the soil produced without producing too much for the
space I have.

Q2. If I don't get a composting bin, can I collect the plant material in a
large plastic pot and mix it with a bit of soil? I did this recently and it
got very smelly: I had left a tray under the pot to catch water as I didn't
want the mixture to dry out. I'm wondering if this will only create a fowl
smell and be a breading ground for disease, which I will then transfer to my
plants. I want to recycle plant debris, but is it going to be feasible
without a proper compost bin?


--

Second dilemma: I put trays under the pots and troughs to measure how much
water is filling the troughs and pots and to catch excess water so that I
could re-use it. If I don't use trays, water leaches from the pots and
creates a build up unsightly red-brown stain, which when cleaned, leaves a
white residue build of what looks like it might be some kind of mineral in
the potting mix. This is impossible to get off the tiles. I want to keep the
place in good order so that when it comes to selling it, it looks almost as
good as the day we bought it.

So, when I water, I water slowly and I stop when the water starts to seep
out of the pots & troughs. Occasionally it rains hard after I water the
plants and there is an over-flow of water. I try to hold out from watering
with the hose, but sometimes the rain does not come when expected and I give
the plants a good drink on one of the two days we are allowed to use hoses.
It is very hot and windy up here.

I collect the water to re-use it, to stop the nutrients from going down the
drain and to stop the staining of the tiles.

Q. Is it bad to use this collected water to water *other* plants in the
area? Some of my plants have become diseased and before I thought about the
possibility of transmitting them through the water in the trays, I had
already put all the collected water into a tub, which I then used to water
plants which had not caught as much water.

Relying on rain water is not a very reliable way of watering my plants as
the ground area around the plants is very limited. Sometimes the foliage
area of the plant acts like an umbrella, causing the rain to fall around the
pot rather than in it.

I'm finding that there are difficulties in managing a roof garden. I cannot
collect rain water from the roof because I am in an apartment. When the rain
falls on the large paved area, it all runs done the drain. I have written to
a number of people asking if they can work out a system of collecting water
from the paving if I blocked the drains. I think it will be a while before
that problem is solved.

I have two more queries:
1) I had started putting dead plant matter into trough with about 20cm of
soil in it - I've been holding out to get the right plant for the pot. There
is good drainage in the pot and the leaf material has slowly been breaking
down in the pot - but so slowly that I have no idea how long it will take to
break down without any worms in there.

Does anyone know if it'll be a problem if I just cover up this layer of
leaves and soil and plant the new plant on top of it? I'm don't want to
encourage any diseases which might affect the new plant.



2) I'm also wondering if I should put worms into the pot soil. If the worms
drop out through the holes in the trough or drop off the top of the pot,
they cant get back in. If for some reason it gets very hot, I'm worried that
I might get mass panic in my worm population.



Cynthia.

"Cynthia" wrote in message
...
I have two more queries:
1) I had started putting dead plant matter into trough with about 20cm of
soil in it - I've been holding out to get the right plant for the pot.
There is good drainage in the pot and the leaf material has slowly been
breaking down in the pot - but so slowly that I have no idea how long it
will take to break down without any worms in there.

Does anyone know if it'll be a problem if I just cover up this layer of
leaves and soil and plant the new plant on top of it? I'm don't want to
encourage any diseases which might affect the new plant.



2) I'm also wondering if I should put worms into the pot soil. If the
worms drop out through the holes in the trough or drop off the top of the
pot, they cant get back in. If for some reason it gets very hot, I'm
worried that I might get mass panic in my worm population.

just a couple of comments:

generally speaking, you shouldn't have worms in pots, however, in a big
trough where it's moist & roomy & there's decomposing matter for them to
eat, it shouldn't be a problem - they won't overbreed themselves out of the
space available. either it will be fine for them & they'll multiply only
according to the conditions, or they won't like it & will all die. you'll
find out ;-) i wouldn't worry about them falling out. when it rains a few
always manage to mess things up & die on the path, but they should be mostly
all right. they are more limber than we think ;-)

generally, you'd compost on earth. i am thinking scraps in a pot with soil
(and _moisture_) would work but might not be as efficient(?) - but
everything should break down. the smelliness is probably just lack of
aeration; anaerobic composting is smelly whereas aerobic composting smells
nice & earthy. try adding a little garden lime & stirring it round regularly
for more air. i just got a tumbling composter, (it's my new love!!!) and it
might be a good idea for your situation!! they're a bit pricey, but they sit
up off the ground & can be put anywhere sunny, are easy to use & very
efficient, you don't need to sit it on soil, you don't need to water it. and
it's fast. compost ends up being 25% (or less, ime) of the volume of raw
materials so you are unlikely to be inundated with it.

personally i'm a very unhygienic gardener, so i'd be throwing water around
from one pot to another, & planting on top of decomposing things & wouldn't
worry one iota :-). some gardeners are real clean-freaks though & won't even
take a cutting from someone else's garden. so, there you are - i think
that's something you need to decide yourself based on if you have any
disease present anyway (probably not), etc, as there's a really wide range
of what people will do and recommend.

your garden sounds fun!! good luck.
kylie

Kylie, you've put my mind at rest. All the answers I was hoping for :-)

You are probably right to that I don't have (as much?) disease in the garden
as I worry I might have. We had a plant delivered over the weekend and I
took the opportunity to ask a couple of the guys about what was going on
with the plants. They were convinced that the brown patches on the viburnum
odoratissium leaves was burning off and that the die back on the 'snow in
summer' was probably caused by over watering.

Thank you for the info on the tumbling composter, I will definitely look
into it as I don't want to put garden waste into the bin.

I'm a bit of a clean freak, but that's from worrying that if I'm not, things
will go wrong, so each word of reassurance from a more experienced gardener
means I can relax that little bit more.

Thanks so much and all the best with your gardening too ;-)

Cynthia.