Time to prune wisteria

Although the feeling rarely endures – last year we had our biggest snowfall ever on July 16th – it’s good to strike while the horticultural iron’s hot.

July is my big month for pruning, starting with wisteria.

There are many forms of this huge, dramatically beautiful climber and they flower better if pruned twice a year, immediately after flowering and again in winter.

Cutting back branches to two or three flower buds encourages bigger flowering spurs. Flower buds are easily distinguished from leaf buds. they are plumper and rounder.

While I’m at it I remove a few of the oldest, longest branches in a feeble effort to keep the plant in check.

Ornamental grape vines (Vitis) can also be pruned now. Remove side branches and retain two or three leaders. Next season’s branches will quickly create a leafy canopy and you’ll avoid a build-up of old wood.

Summer flowering perennials can be cut back, divided and replanted in July. Hardy catmint (Nepeta), Michaelmas daisies, veronica, sedums and many others have a neat mound of leafy growth beneath their dead or dying flower canopy, ready to take off when days become longer and warmer.

Cutting back perennials clears the way to lime beds if your soil is acid. Test with a $20 kit from your garden centre and aim for a pH of around 6.5.

Lime is easy to spread – fill a plastic washing up bowl and throw out approximately one handful per square metre, preferably with the wind behind you. You can rake it into the ground or leave for the first fall of rain to wash down.

Dolomite lasts three times as long as garden lime (it costs slightly more) so I make a diary note when I spread it.

Lime turns hydrangea flowers gloriously pink or red. Aluminium sulphate turns them blue, though it doesn’t last long on alkaline soil and needs topping up every winter.

Mid-winter is the best time to take hardwood cuttings of deciduous shrubs. These are the easiest cuttings of all with success pretty well guaranteed, so go for it.

Propagating a precious treasure means you never have to worry about losing it to the inevitable droughts, floods and grasshopper invasions that plague all country gardeners from time to time. Replacing plants is expensive, far more fun and rewarding to produce your own.

A hardwood cutting is a 15-20 centimetre piece of stem, removed from the most recent growth. Pop one third into the ground, tread in firmly and keep damp, this is vital.

In spring (or later, be patient, ha) tiny leaves will sprout, the longed-for sign of success: your plant has roots.

Once a stem has rooted you can pot it up to plant out, either next autumn or the following.