Hi there.
I am very new to the world of electronics and solar and would like some advice on the battery and solar panel system that I will require for the following project.

I am attempting to set up an automatic watering system to keep my plants well fed during long stays away. I have a 12 volt bilge water pump that will be submersed in a large drum of water and will be connected to plumbing feeding to approx 10 pot plants, all that have another pumping system pluged into the bottom to allow the drained water to return to the drum.

I have purchased a 12volt digital timer that will be programed to turn the pump on 6 times throughout the day. (Every 2 hours starting at 6am). It will run the pump for 5 minutes.

What type/size deep cycle battery will I require to run this system?

What size of solar panel will i need to keep the battery charged?
(The location gets fantastic sunlight all year round; west brisbane, queensland, australia)

What size wiring will i require to hook them all up?

Your help and advice would be greatly appreciated.

Here are the specifications for the pump and timer;

Timer;
Contact Rating: 16A @ 30VDC
Operating Voltage: 12VDC
Max. Current: 8A
Voltage: 12V
"ON" Power Usage: 3W
Backup Batt: 1.2V NiCad


Pump;
Rated power: 50W / 5800rpm
Current: 5.4 amps
Voltage: 12V
Rating: Continuous

Very interesting project, im glad to help.

PANEL SIZING
Ok we have the pump running for 5 minutes 12 times a day, so that's a total 1 hour per day. There fore, every day our pump is using up 50W for 1 hour, or 50Whr.
In Brisbane, you'll have an average of around 6 full sun hours a day, so a 10 watt panel will give you average of 6hrx10watt ~ 60Whr per day.
Now assuming a system efficiency of 85%, after battery charging and storage, we are only seeing 51Whrs from our solar power.
So a ten watt panel would be sufficient.

You can make the panel slightly larger, 12 - 15 watts if you like to compensate for cloudy periods.

BATTERY SIZING

Now your using a total of 50Watts for 1 hour each day. To ensure you don't stress the battery, and have some supply for a full cloudy day, we need our battery that store double the power we use in 1 day. so we need a battery that will store 50W x 2Hr ~ 100 watts for 1 hour.

Using a 12 volt system and SLA battery the current capacity would need to be 100watts/12hrs = 8.33 amp hours, however, we usually get less to to internal resistance of the battery, so aim for a 12volts 10Ah battery.

Overall, you looking at around a 12 watt panel and 10Ah battery. Larger panel and battery would be better, just make sure you don't over charge the battery.