> I have a drip irrigation system to water my roses, each
> rose has two 4 litre/hour drippers. At the moment I am
> leaving the system running for an hour in the late evening
> each day. The ground seems damp enough and the roses
> are flourishing but it seems a lot of water for each rose.
> Can anyone give me an idea how much water a four year
> old [or older], bush rose, would need?
> I live in Sydney [Aust.] and we are in the middle of a
> severe drought so any possible savings without
> compromising the plants is in the general interest of
> the community.
Last year I didn't use my drip irrigation at all: here in North
Florida it either doesn't rain for months or it rains to the point
of flooding. Anyone growing any crop apart from pine trees
for lumber pretty much has to have some sort of irrigation on
standby: either it'll barely be used, or it'll be essential to
keeping the plants able to produce any crop at all.
I found a couple years ago that during a drought, an hour with
one 4 liter/hour dripper daily was about right for my (slightly
younger and smaller than yours, then) bushes, but my soil holds
moisture well even though it's largely sand (the rest is clay,
with pure clay underneath for quite a depth above limestone).
My guess: you're giving them about what they like, but they'd
get by on less: roses are greedy for water and so long as the
drainage is good they'll take whatever you give them. I'd try
cutting back a little (maybe 45 minutes a day instead) for a
week or so, and seeing how they fare.
Again, this was a couple years ago in Florida, where the air
is rarely dry, and when even during droughts a foggy morning
is likely. I didn't have mulch either.
Mark. Gooley, from north peninsular Florida (frost this morning,
frost forecast for tomorrow morning)