Hi,
For water to freeze in the ground you would have to have below 0 temps for a sustained amount of time. The ground will actually heave and get higher and is rock hard. I do not believe anywhere around you could possibly get that cold. We have been -6 at night all week and the ground is no where near freezing/heaving.

From my experience living in areas with real cold, it is better to have water in the ground. You do not want a plants drought stressed as well as cold stressed. I am not familiar with tropical plants, but I would not do any pruning until after winter is over. Try covering plants with bits of sheet or leaves, anything over them will help to keep them warmer. If you have potted plants bring them next to the house or under eves or trees.

I was in Bellingen a few years ago when there was a unusual hard frost. We had a lot of palms and other plants loose leaves, but none died.

Don't let your tender plants get stressed through lack of water - they really will suffer with frost then. Spraying plants with a seaweed mixture helps them resist frost damage. Or you can spray them with Envy, which coats them with a plastic type film but you have repeat it every few weeks. I always wonder how the leaves transpire with Envy on them.

OK, then: water as needed and spray with seaweed (which I use often) or Envy (must buy some). Thanks!

g'day cestrum,

water will freeze in the hose from anywhere from around +3c downward, and the westernly sub's of brissy noted for cold, archerfield rated the other day with a very low morning temp' and just look at up ipswich way not that far from there as the crow flies, even yesterday they had -1c i think and -3 (with a -6 feels like) or so the other day. we've had 2 frost here on the northern bayside and temps wouldn't have been as low as those western areas.

i need to get an outside thermo' going just for air temp, then you need to remember grownd temp is a lot lower than that. so ok plants need enough water to keep them going but in winter usually in the mornings.

by your description frost sensative plants are already suffering from frost, or yes cold if you put it that way but the cold you are getting is critical cold usually causing black frost and associated with cold fronts moving through.

reckon from my expereince in the bush maximum mulching to keep the root runs warm will be more of an advantage than adding moisture that is likely to add to the freezing problem. with bananas and those things you may need to put a frost cover over the top of them. and even if tops get burnt off with maximum mulching the roots will still be there to come back next season. which is a long way off yet this is going to be a cold hard dry winter by our standards.

len

Here is a link that might be useful: lens garden page

just checked my weatherzone.com.au page and it shows current ipswich at -1.2c and archy at 3c with a dew point of .9c. so that's pretty cold and there could easily be frosts around. shoud have checked ours for coparative but generally around 9c++ or so warmer than ipswich.

good site that weather zone i think the reading come every 1/2 to 1 hour.

len

Hi,
With mild frosts, (the type we are talking about) it is proven better to remove mulch from around sensitive plants. The sun will heat the soil in the day (if exposed) and this heat is then released at night to help warm the plant. Mulch will increase the effects of cold on the plant by decreasing the ground temperature and preventing redation of heat from the soil to the plant.

Mosit soil is much warmer than dry soil. Moist soil produces heat, holds heat and releases heat which keeps the plant warm.

here is referrence with studies
http://anrcatalog.ucdavis.edu/pdf/21429e.pdf

Covering the plant on nights when frosts are expected is the best way to help sensitive plants. It holds heat radiated from the ground around the plant and it prevents frost crystals from forming on the leaves and stems.

Deb

From; Frost, freezing damage and mulch
http://www.global-garden.com.au/burnley/jul01dte.htm

Conditions are quite different in Australia. Here, the winter sun is consistently quite warm and temperatures rarely drop below -6ºC. The soil absorbs heat during the day and radiates it at night, so reducing the likelihood of frost. Radiant heat is lost most quickly on still, clear nights and frosts are most likely to occur under these conditions. If garden beds are mulched with organic material such as hay, straw, pine bark, compost, etc, the soil is unable to absorb much heat during the day. (Just as mulch keeps soil cooler in summer by blocking solar radiation, in winter the same blocking means there is less stored heat in the soil to prevent frost.) During the night the heat is quickly lost and the surface freezes. This is why you will often notice frost lying on mulch while bare soil is frost-free.

For Australian gardeners, the best way to avoid frost damage is to have soil that is clear of organic mulch and weeds. In frost-prone areas raking mulch away from plant roots in winter will maximise the heat that can be absorbed during the day and radiated at night. Moist soil absorbs more heat than soil that is dry, and soil that is uncultivated absorbs heat more effectively. (If soil is light in texture or if it is 'fluffed-up' by cultivation, the air pockets act as insulation, preventing heat from being absorbed readily.) Bare, moist, compact soil will most efficiently absorb and radiate heat, so protecting plants against frost. Air temperature in such a case can be 1 Â 2C higher than mulched or grassed soil. Mulch can then be reapplied once the danger of frost is over. The precautions discussed here are only worthwhile if you are growing plants that are likely to be damaged by the typical frosts your area suffers. If your plants are hardy there is no need to go to this trouble.

Profile: Dr Peter May is Deputy Head of Campus, University of Melbourne - Burnley College. He is a soil scientist with a range of horticultural interests including plant performance in the landscape, turf and viticulture.

The role of mulch in protecting plants against frost is obviously a controversial one (probably because, as Deb says, traditional practices arose overseas where it's cold day and night in winter). I'll water as necessary, but there's not much I can do about the mulch as my garden beds are actually built on about a 20cm layer of sugarcane mulch, with the plants growing in soil pockets in the sugarcane. Creating new soil (as the organic material breaks down) is a slow process ...

an old trick from real frost country - canberra - was to set up a misting spray near you very sensitive plants and mist all night long - wastes water and if it does get really cold you can suffer the shock of everything being an icicle in the morning

another trick is to mound stray around your frost sensitive plants in the evening and then remove it in the morning - another trick is to set up a couple of poles and string some hessian or shade cloth over the plants - bit hard with bananas tho

Mound stray mulch? Or soil? Or just $10 bills :-)

I think in some ways the 'real frost country' has it easier, because frost-tender plants such as fruiting bananas and frangipanis would never be grown outside there anyway. It's this wretched combination--subtropical for 6-7 months of the year, then warm during the day and frosty at night for the remainder--that makes gardening so tough. The cold-hardy plants find it hard to survive the humid summers and the tender sub/tropicals have the same problem with the frosty nights.

But you all know this; it's just me who's having a hard time coming to grips with it :-(

Funny thing is that the big banana (not The Big Banana TM, which is something else entirely) just a few metres along the fenceline hasn't suffered at all. But it's growing right in the corner (where the two fences meet) and probably has a slightly warmer microclimate. Plus it's older: I'm hoping the baby will toughen up a little with age. And the season for sweet potatoes is over, anyway.

My own experience has been to lightly water plants (in frost prone areas)just before the sun gets to them each morning.This thaws the frost before the suns rays can expand the ice crystals. It seems to work?

As Follicle says, water the plants before the sun hits them if you don't mind being out in the cold :)

I wouldn't worry about a bit of frost damage on some plants though. We used to live in Conondale near Kenilworth where it gets colder (too cold for me) than Ipswich and had Frangis, hibiscus and similar. They did get some damaged leaves but came back once the weather warmed up. Remember frost flows downhill so building up something on the higher side might help protect the plants a bit more.