Quick guide to pruning ornamental plants in the garden

Many ornamental plants will need some form of pruning at some time. Pruning out dead, diseased and damaged growth, encouraging healthy growth, increasing the density, reducing the size of the plant, prolonging the flowering season and promoting bigger blooms are some reasons why pruning is used in the cultivation of plants.

As long as pruning cuts are made in the correct position and cleanly, the plant will heal. Using special paint to seal the cuts is not usually necessary if the cuts are made correctly with clean pruning equipment. Always use pruning equipment appropriate to the size of the branches you will cut. The most commonly used pruning tools are secateurs, loppers and pruning saws. When tying up stems, use soft flexible ties and allow for some movement of the stem. Remember to regularly check and remove ties, as these cause significant damage to plants if they are left on unchecked.

Position of the pruning cut

When making pruning cuts on smaller stems and branches, the position of the cut is just above a node. A node is where a bud, leaf or stem emerges from a branch. The internode is the space along the branch between the nodes. If the cut is made too far into the internode, then the branch usually dies back to the node. This area of die back is a potential entry point for disease.

Note: The angle of the cut is not as important as getting the position right. Ideally, the cut should angle slightly away from the bud so that water is directed away from the bud. Do not cut on a sharp angle as this makes a large wound and may damage the bud.

When pruning main branches, the cut should be positioned so that the branch – bark ridge and the collar are not damaged. The branch – bark ridge can be seen on most trees. It is the ridge of bark on the top side of the attachment point where the branch is attached to the trunk. The collar is harder to see, but it is the swollen area underneath the attachment point of the branch to the trunk. Even if you cannot see it, the collar is still there and should not be damaged. The pruning cut should be made just outside this area.

If you leave a large stub, then this usually dies back and is an entry point for disease. Undercutting a branch before cutting is recommended, particularly on larger branches, as this prevent the bark tearing and damaging the branch collar. Avoid damaging the bark, as this can cause significant damage to the tree and provides a potential entry point for disease.

Other plants

Plant	When to Prune	How to Prune
Clematis	After flowering and in late July	After flowering prune off around half the growth. In late July prune to the 2nd or 3rd set of strong buds. Prune out all weak growth altogether.
Wisteria	Winter and Late Spring	Prune back laterals to the 1st or 2nd bud in winter. After flowering in late spring prune back long wispy growth.
Hydrangeas	Either in February or in winter	Prune flowering stems back to the first set of plump buds. Prune dead and weak growth out at the base.
Bulbs and Lilies	After flowering, when the foliage dies off/ is yellow or brown.	Ideally you should be able to pull the foliage off the top of the bulb easily. For Liliums prune the foliage back to just above the ground.
Azaleas	Late spring	Prune after flowering. May be pruned back hard to promote bushy growth.
Grevilleas, Banksias and Callistemons	After flowering	Prune back just behind the flower.
Salvias	Late summer, winter	Prune back by half in late summer and hard in winter
Canna Lilies	Winter	Prune back stems that have flowered to 15cm above the ground.
Lilac	Early Summer, Winter	Prune behind the spent flowers in early summer. Prune lightly for shape in winter.
Hibiscus	Spring	Prune out old, dead and weak growth and prune to shape.
Camellias	Spring	Prune to shape only. May be cut back hard to rejuvenate old bushes.
Lavender	After flowering	Deadhead, then prune back foliage by one third. Do not prune back into old bare woody stems. Old bushes best replaced.
Miscanthus	Winter	Can keep old flower heads through much of winter, then prune back to approximately 10cm above ground.
Weeping Cherries	Winter	Prune young weepers to outward facing bud to encourage a thicker canopy.
English box	Spring	Clip through the growing season as required.
Conifers	Early Spring. Mid Summer	Be wary of pruning hard into bare woody stems. Prune lightly in early spring. Prune very lightly in summer, only if needed.
Fucshias	August and throughout the growing season	More severe pruning in August to allow a strong framework of branches for the new growth. After each flush of flowers pinch the tips back.
Gardenias	Spring	On younger plants light pruning only is necessary. On older plants more severe pruning will encourage bushier growth