ESSENTIALS FOR ROSE GROWING SUCCESS
AUTUMN ROSE GROWING CULTURE NOTES FOR
SOUTH AUSTRALIA
In South Australia roses are a favourite choice for the garden because they are easy to grow and maintenance is relatively simple. The frequent balmy days, particularly later in autumn, are ideal for producing a magnificent autumn flush of high quality, colourful flowers. Here are a few tips to care for your roses.
March often sees a continuation of summer-like conditions with some very hot days and lower rainfall. Milder days generally appear in April and continue into May. Seasonal opening rains often occur in late April or early May, heralding the onset of the wetter, colder months.
The average daily temperatures in Adelaide in March are 26.5°C, April 22.8°C and May 19.0°C. Average rainfall in autumn is about 26mm in March, 40mm in April and 61mm in May.
Evaporation rates decrease from their summer highs and daily sunshine hours reduce from around 10 hours per day in January and February to 8.6 hours in March and continue to decline to 5.4 hours in May.
So, what does this mean for our roses and how can we care for them during autumn?
- WateringIt is essential to maintain a regular and thorough watering regime. We can be easily misled by milder days and cooler nights. However, the average March and April rainfalls are generally insufficient to maintain healthy Autumn growth in our roses. Like summer, it is best to look at the forward weather forecast for the next 7 days. If the weather forecast is for warm to hot and dry conditions, hydrating roses with a weekly thorough irrigation is recommended. If rain accompanied by lower-than- average temperatures occurs, irrigation may be halted for a period and recommenced when a dry, warm to hot period is forecast.Generally, irrigation is needed until the opening seasonal rains occur late April – early May. If unsure whether watering is required, scratch down 3 to 5cm below the ground under a rose plant. If dry at this depth, apply water immediately. Remember, the rose has many roots just below the surface and these can dry out, hindering optimum performance.
Roses in pots also require regular watering during the autumn months.
- MulchThe mulch which was applied late spring or early summer will be breaking down in autumn and its thickness reducing. Providing sufficient mulch was initially applied, adequate cover will remain to reduce evaporation, continue to cool the roots and feed the earth worms and beneficial microbes in the soil during autumn. However, if all mulch has disappeared, a fresh application of Neutrog’s Whoflungdung (certified organic mulch) in early autumn is recommended. This mulch is biologically activated, nutrient rich and weed free. It comes in convenient 20kg compressed bales and can be taken to and easily spread where it’s needed.
3. Flowering
Autumn is an excellent flowering period for roses. A light, late summer or early autumn trim will ensure a great flush of flowers around 55 days later. This trim is simply removing the spent summer blooms and a portion of the stem down to a healthy pin-head sized bud nestled between the leaf and stem. Stem removed is generally around 15 – 30cm. Importantly, this is a trim and not a prune and sufficient foliage must remain to avoid exposing the stems to sunburn.
The summer – autumn trim is far more effective if it is completed two or three weeks after an application of Neutrog Sudden Impact for Roses. Don’t be concerned if autumn colours are different to spring colours of the same variety. The on-set of cooler nights and less sunlight through autumn often produces more intense colours in some varieties.
‘Brass Band’ showing autumn colour
- FertilisingIf an application of Sudden Impact for Roses was not applied in February, ensure the rose plants receive it in March. Once applied, it should be “watered in”. If possible, and given favourable weather, apply just before forecast rain, which will assist in ensuring the fertiliser is taken to the root zone. If you can’t rely on rain or a sprinkler system, use Sudden Impact for Roses Liquid Fertiliser applied in fortnightly applications until the end of March. Neutrog Go-Go Juice will certainly provide an additional boost to plants after enduring a long hot dry summer.
- Pests and DiseasesOur autumn seasons are generally warm to hot and dry until the end of April and these are favourable conditions for rose growing. As far as pests and fungal diseases are concerned, usually no preventative or curative remedies are required. With the change in season to wetter weather, cooler nights and even heavy dews, in late April or early May, some fungal diseases may emerge. You can choose to do nothing and tolerate some infected foliage or apply a preventative organic oil or fungicide spray mid to late April to ensure plants remain clean well into late autumn and early winter.
- New Rose PlantingsAutumn is the best period to commence soil preparation for new rose plants, including the removal of underperforming old plants. Where a rose plant is to be removed, commence the process in April or early May by removing the old plant. Endeavour to dig-up as many of the old rose roots as possible. If you can, take a half a barrow of old soil out and replace with soil from elsewhere in the garden which has not grown roses. Then apply an application of 10cm of Whoflungdung plus Neutrog Seamungus and Go-Go Juice to the area to be planted with the new rose(s). This should be dug into the ground to at least the depth of the spade or even deeper if possible. If the soil is lumpy from a high clay content, an application of gypsum maybe required.Repeat the application of Go-Go Juice every few weeks until the end of May. Keep on digging over the soil to reduce weed growth and to encourage the earth worms and beneficial microbes to remain very active.
New rose beds or locations should be prepared in the same way, except the removal and replacement of soil is not required. These should be in full sun and free of root competition from trees or shrubs. Preparation should commence on or before Easter.
- Recommended Specialist Rose RetailersAutumn is also the best time to pre-order new rose cultivars. Rose plant producers and specialist retail nurseries release their catalogues listing and describing the varieties available. Order early to ensure you don’t miss out on the roses you wish to purchase. Watch out for release information on new varieties in garden magazines and on social media.If you want to purchase bare root roses in winter, it’s time to order them now. Contact South Australian specialist rose nurseries such as Wagner’s Rose Nursery www.wagnersrosenursery.com.au Knights Roses www.knightsroses.com.auand Newman’s Nursery or your local garden centre. Look at their websites and also interstate specialist rose suppliers. Not all varieties are in abundant supply, especially the new releases. Therefore, order early in Autumn to avoid disappointment. Autumn is a great time for roses and gardeners who provide the care necessary to maximise performance will be rewarded.
