Some like it hot, but not hydrangeas, they need shade and water, says gardening columnist JACKIE WARBURTON. 

HYDRANGEAS and other large, leafed plants will dry out the quickest in the hot weather. Keep them in the shade for the hottest part of the day. 

The colour of the hydrangea flowers can be changed if you prefer pink or blue, but remember white cannot be changed. 

To keep hydrangeas blue, feed them throughout their growing period with aluminium sulphate or iron as a blue tonic from July to October. It can take several years to get them to dark blue. 

Make sure the soil is acidic and the pH is below 6.5. If the pH is above 6.5-7 there will be pink flowers. Adding lime makes the flowers pinker still. 

I have cuttings from an old shrub that I divided and placed in steel-wool pads (not stainless steel, as I want them to rust) and buried them in a pot. I’ll be interested to see if the steel wool will add the iron that I need to turn the flowers blue.

The old gardener’s trick is to put a handful of rusty nails (not galvanised) at the bottom of the hole when planting, which could work as well. 

There are many different types of hydrangeas to choose from. One of my go-to plants in designing a garden is Hydrangea quercifolia. It loves shade and has a lovely contrast with purple foliage and large white/cream flowers. A little unusual is Hydrangea petiolaris, a deciduous climber in Canberra and very easy to prune. 

FOR anyone away during the holidays, there are a few things to help get indoor plants through this time. 

• For peace of mind, make sure plants are in good health before leaving on a holiday.

• Place all the plants in a cool part of the house where there is no direct sunlight to dry them out (the bath can be a good option with wet towels under the pots). 

• Give your indoor plants a good, deep soaking by submerging them in a bucket of water for 30 seconds and drain. 

• Drip trays can be used only as a short-term method as too much water around the roots will cause the plants to rot but see if there is a neighbour or family friend that can come by and check if you are away for longer than a few weeks. 

FOR outdoor gardens, it depends on the weather. 

Irrigation plays a big part in summer and getting this right is the key to a garden looking lusH.

There are many choices of different types of irrigation and engaging an irrigation specialist will help with the most water-efficient ways of watering the garden and what system is best. 

Choosing drought-tolerant plants is a sure way of keeping a summer garden alive. 

THE rain over the last few months has been great for growing herbs and vegetables. Sow and transplant all that you have. 

Some herbs, such as oregano and sage, can be cut back quite hard to make room for smaller plants to grow. Continuously pick off leaves and produce to increase your yield at the same time.

Keep the water up to any shallow-rooted herbs to prevent them from drying out. Mulching will help preserve the moisture as well. 

GREVILLEA robusta is described as a tree not a shrub as most would think and is the largest species in the Grevillea family. 

It is a fast-growing evergreen tree and sheds so much material under its canopy where nothing will grow under them. They are endemic to this area and great for windbreaks on large properties, but not a good choice as a suburban tree. 

They have the most amazing large golden/orange flowers and a terrific food source for wildlife such as the honey-eater birds, rainbow lorikeets and bees. 

Keep the ponds topped up with water for the birdlife and the bees. Plants such as the water irises should be flowering now. 

jackwar@home.netspeed.com.au