Growing roses 101

Contents:

• When to grow roses
• How to plant roses
• Pruning roses
• How to fertilise a rose bush
• Rose pest and diseases

The core requirements for growing roses are sunshine, compost and manure, along with a simple program of pruning. There are plenty of organic products on the market to treat pests and diseases, as well as specially formulated rose foods to help bring on the very best blooms.

When to grow roses

May, June and July are the months to plant bare-rooted roses in Australia. You’ll find them at nurseries, specialist rose nurseries and mail-order suppliers.

How to plant roses

When growing roses, it’s important to prepare the planting spot at least three weeks beforehand. First, find a suitable long-term position. Roses must have at least half a day of sun (preferably from the morning) right through the year, so consider the seasonal changes of the sun’s trajectory that may cause deciduous trees or structures such as buildings or fences to block the light at various times.

They like good drainage, so if you have a heavy soil, consider building a raised bed or mounding the soil. If clay is present, mix gypsum into the topsoil and avoid digging into the deeper clay layer as this will create a water-holding ‘sump’. Blend plenty of compost into the soil. In acid soil areas, add a handful of lime per square metre, and mix in well.

Roses are often grown in specially designated rose beds, although some free-flowering shrub varieties can be mixed in with other plants to create a softer, cottagey effect. Standardised or ‘tree’ roses are useful for giving a more formal look to a garden, especially if they’re planted in delineating rows. Small or miniature rose varieties are often at their best in containers, while shrub roses are usually planted about 1m apart. It’s important, especially in humid climates, to leave breathing space between rose plants so there’s good air circulation, as this leads to lower rates of disease. Good spacing also makes it easier to prune and feed the rose plants when required.

Pruning roses

Pruning is needed to remove dead or diseased growth and to encourage new flowers. As soon as your rose bush has finished a show of blooms, cut them off (called deadheading).

Winter-prune: Roses are hard-pruned in winter and are on most gardeners’ to-do lists. July is the ideal time to prune roses in most areas, but in very cold zones, especially those subject to late frosts, leave your pruning until the end of winter. The aim is to remove about half to two-thirds of last season’s growth to encourage new growth, as this will produce flowers in spring and summer.

Find a step-by-step method for pruning roses, here.

Summer–prune: Repeat flowering rose bushes can tend to look a bit ordinary at this time of year. Summer rose pruning is like winter pruning, only not as hard. The aim is to give them a general tidy up and reduce their height by about a third.

Find more tips on summer-pruning roses, here.

How to fertilise a rose bush

Roses can do with a feed three times a year, at their first flush in spring, at the start of summer and again at the start of autumn. Giving your roses a feed will provide the plants with all the nutrients they need to produce a super show.

1. GIVE the soil around the base of the bushes a good soaking, which will prepare it for fertilising. Apply a few generous handfuls of organic fertiliser around each bush.
2. SPREAD a 3–5cm layer of compost around the bushes. If you’re short on homemade compost, buy a good quality commercial product.
3. COVER the soil with a 5–7cm layer of fine shredded organic mulch. You can use tea-tree mulch, sugarcane, lucerne or straw.
4. GIVE the bed a final soaking to settle everything in and activate the organic fertiliser. If conditions are dry, follow up with a good soaking every 10 days or so. Early morning is the best time to water roses, so that the foliage has time to dry out during the day, which reduces diseases.

Rose pests and diseases

Roses are prone to a number of pests and diseases, so it’s important to get in early with the right controls to keep your plants in top condition.

Powdery mildew

This disease causes powdery patches on rose leaves, stems and buds.
Here’s what you can do:

• Follow the tips (below) for controlling black spot
• Change the variety, as some roses are more vulnerable
• Strengthen your plants by giving them regular doses of liquid seaweed, following the instructions on the label

Find more tips on managing mildew, here.

Black spot

A fungal disease that causes ragged-edged black spots on the leaves, followed by leaf yellowing and leaf drop. It looks ugly and weakens the plant.

Here’s what you can do:

• Keep foliage dry as the fungus infects plants when leaves remain damp overnight
• Grow roses in full sun with lots of space around them
• Fertilise regularly, especially with a product high in potash
• Spray plants with a rose fungicide or make up a spray based on bicarbonate of soda
• Pick up any infected leaves that are lying on the ground, and dispose of them in the bin, not in the compost

Aphids

This is the main insect that attacks roses, feeding on soft, new growth. Numbers increase exponentially when conditions suit them, and shoots become smothered in aphids. These pests weaken plants by sucking their sap, and carry diseases from one rose to another.

Here’s what you can do:

• Squash aphids by hand, which is easy as they tend to cluster together on new growth
• Prune off badly affected tip pieces, squash them and bin
• Grow a mix of flowering plants in your garden to attract natural aphid predators such as native wasps and hoverflies
• Spray with a pyrethrum insecticide, but avoid doing this if beneficial insects such as bees, lacewings or ladybirds are around. Adult ladybirds eat aphids and their larvae, which look nothing like the adults as they have narrow, spiny, segmented bodies, devour even more of the pests than their parents, as do lacewing larvae.

For more tips on controlling aphids, read here.

Thrips

These tiny sap-sucking insects spoil light-coloured blooms, especially in spring. The edges of petals look as if they’ve been burnt. Thrips are particularly hard to control when they shelter in full double blooms.

Here’s what you can do:

• Put foil under plants to reflect the light – thrips don’t like glare
• Apply insecticidal soap spray
• Hang sticky yellow traps made from plastic coated with petroleum jelly, or cut sticky yellow tape into small sections
• Plant some decoy flowers nearby, such as alyssum (Lobularia maritima) to attract pests away from the roses
• Wait until the weather changes, when the problem will naturally reduce

Whether you’re a novice gardener, or rose enthusiast, there’s no doubt growing roses is rewarding. They will bring elegance and fragrance to any garden — and make lovely cut flowers in your home!

Text by Judy Horton, Jennifer Stackhouse & Phil Dudman