Digger's Club MapsClick on the relevant map to be taken to the enlarged version on the Diggers Site. For those interested, you can read a small article regarding these here.
Cold Zone MapThese are similar to the USDA Hardiness Zones, in that they show the absolute minimum temperature that can generally be expected in an area. The Digger's Club Cold Zone Map is in centigrade only, but if you want to compare this to the USDA map (see below) then they helpfully provide both centigrade and farenheit. This is important for those growing plants that require a period of winter chill, or who want to grow plants perennials that are not hardy below a certain temperature.
Hot Zones MapThis map shows the number of days over 30c you can expect in your area and is great for those who might want to grow plants from cooler climes or who are considering whether they can grow more tender perennials.
Combine using the cold zones and the heat zones map and you will be able to determine whether your climate is suitable for a certain plant.
Growing Weeks by AreaThe growing weeks by area is particularly useful for us gardeners who like to grow our own veggies. This map tells you the number of growing weeks over 15c for your area, which you can use to check against the number of growing weeks required to grow something from seed. If they need more weeks than you have, you might then consider growing those plants under cover or at least starting them off under cover.
BOM Climate MapsFor those of you who might be looking to grow vegetables, or other non-drought tolerant plants, you may of course also want to know what your likely rainfall is.
The BOM website provides maps that allow you to find out a large range of information specific to your area. Of particular use are the number of days of rainfall above a certain level. This can be used in conjunction with other information (soil type, plants grown, evapo-transpiration etc) to determine an fairly accurate watering schedule for your garden.
This is particularly important over the hot, dry months in Australia, especially when we have water restrictions.
We also have a tendency to over water our plants, particularly vegetables, causing leaching of nutrients, slowing down root development and growth, not to mention encouraging certain pests and diseases.
I found the maps showing the average number of days with rainfall to be invaluable when initially planning out a garden. You can choose the month and the rainfall amount from a drop down list.
Check out the full range of useful maps here and for more specific information on historical rainfall for your area (useful for those with automatic irrigation systems or who wish to design watering schedules), then have a look at the climate data online here.
Many of the gardening reference books available in Australia still use the USDA Hardiness Zones when talking about suitability, particularly for ornamentals. Once you've used the Digger's Club Cold Zone Map to determine your zone, you can use the scale on the USDA map to work out the equivalent hardiness zone.
USDA Hardiness Zones
For example, in Melbourne you are Cold Zone 10, perhaps 9b if you live a bit further out from the city. This would be the equivalent of 10a, or 9b, using the USDA system. Note that not all zones transfer so neatly!
Soon I'll be writing up some info on planning water schedules and budgets for you guys at home, which will be useful whether or not you have an automatic irrigation system or not.
Come back soon! :)