A guide to autumn hedge planting and maintenance for Sydney gardens
Hedges are often taken for granted - but with a little bit of care and attention, they add a lush and lovely element to the garden. Hedges create shelter and privacy while also acting as a backdrop for other plantings - but proper hedge maintenance is essential for their ongoing survival.
The best plant choices are dense, evergreen shrubs with smallish leaves and branches making them easy to prune and maintain. Some hedges are simply green, while others are variegated or display colourful new growth, but flowering plants such as camellias also make reliable and attractive hedges.
Hedge planting basics
Perfect hedge plant choices
Autumn is the perfect time to get started with a new hedge as it is planting season. Thanks to the warm soil and mild conditions, the hedge plants can get their roots established ready for a burst of growth when spring comes around. Reliable hedge plants include lilly pilly, murraya, sasanqua camellia and viburnum (particularly Viburnum odoratissimum), all of which can be pruned into formal hedges. These plants can be trained into hedges around 2-3m high and grow best in a bright, sunny position, although all tolerate light shade, and especially afternoon shade. For even growth, select named varieties.
Other good hedge plants are Japanese box (Buxus microphylla var. japonica), which is a good choice for a low but very neat green hedge around 50cm high, and plumbago, which can be grown as a loose informal hedge or trimmed as a formal hedge.
Hedge preparation and planting
Prepare the soil well before planting by digging it over, removing any weeds, rocks or old roots. Dig organic matter such as compost and aged manure into the soil ahead of planting. Want more detail on creating the perfect soil environment for autumn planting? This article has all you need to know. If you're growing your hedge alongside a lawn, consider installing some garden edging to keep your hedge and lawn separated and prevent root competition.
The spacing between each hedge plant relates to the width of the mature plant. For example, a shrub that grows 2m wide should be planted 1m apart. Usually hedges are planted around 60cm-1m apart. Pay close attention to the spacing listed on the pot or plant label. Closer spacing will create a hedge sooner, but the plants will need extra care and attention as they grow.
To get a perfectly even hedge, set the plants out in their pots so they are equally spaced. The first and last plant should be half a space in from your intended start and end points. For example, if your chosen plants have a recommended spacing of 1m, your end plants should be placed 50cm in from the end points of your hedges. Use a stringline stretched the length of the hedge to get them planted in a straight line. Make sure to allow space both in front of and behind the hedge. This is necessary not only for growth, but also to allow access for pruning and maintenance.
When calculating the number of plants needed for the hedge, it's a great idea to buy a couple of extra plants to grow elsewhere in the garden or in pots. This means you'll have spares on hand to replace any hedge plants that fail. Keep a note of the variety planted in case you need additional plants in the future.
Hedge plant care
Remember, hedge plants are a long-term feature and the individual plants will compete with each other for light, water and nutrients. Therefore, it is important to look after new plantings so they establish a strong root system and even growth. There are also a few things you can do to make hedge maintenance much easier for you as a gardener. Prune your hedge upon planting so that the plants are all the same height, and to encourage bushier growth. If possible, lay out a watering system along the line of plants to make it easy to keep them well-watered. Liquid feed after planting and regularly during the hedge's active growth period (spring to early autumn). Fertilise with a complete, slow-release granular formula twice a year (autumn and spring). Place mulch around the plants to deter weeds.
If one plant within the hedge grows more slowly than the others, there could be a few reasons. Check that it is getting adequate water, is well-drained and that its growth isn’t being affected by other factors such as weeds, rocks beneath the soil or exposure to wind or excess heat.
Hedge maintenance: pruning
Aside from being the perfect time for planting, autumn is also the ideal season for hedge maintenance. The big deal with hedges is pruning - and it's important to remember that a full and lush hedge requires time and patience. As a rule of thumb, the quicker-growing the hedge, the more frequently it needs to be pruned. Ideally, you'll prune your hedges twice a year with a trim at the end of summer or in early autumn before the cold weather sets in, followed by a prune in late spring after new growth has hardened up. If the hedge has flowers, wait until after flowering to prune. Fast-growing hedges may need more frequent pruning to encourage fuller growth and prevent gappiness through the middle.
Before getting out the pruning shears or electric trimmer, check the hedge carefully looking for bird or other nests. This check is especially important in spring when many birds seek the shelter of a hedge to build their nests. Often just observing the hedge will alert you to the presence of birds. If you encounter a nest, simply stop pruning. Within a matter of days or weeks the eggs will have hatched and the young birds fledged and left the nest. It is then safe to continue your hedge maintenance activities.
While many gardeners prune by eye, it is safer to use stringlines to keep the hedge level and square. Also prune the sides, tapering the cut slightly so it is marginally narrower at the top than the base. This allows sunlight to reach the base of the plant and avoids having a bare base.
Hedges can be pruned from when they are first planted to keep them bushy and to encourage leafy growth from the top to the base of the hedge. After pruning, give the hedge a light feed and extra water to feed the new growth that pruning encourages.
For more information on pruning, read this article.