Container gardening has never been more popular. Potted roses are a stylish way to introduce colour and fragrance to brighten up your verandah, patio, courtyard, balcony and other garden areas.
With their long flowering season, rounded shrubby growth and fragrance, roses make highly effective containerised plants. They are ideal for placing at entrances or along pathways or on patios, where their gorgeous, often beautifully fragrant flowers can be enjoyed.
CHOOSING WHICH ROSES TO PLANT
Generally, you should consider selecting varieties that have an even growth habit, maintain a regular shape and good repeat flowering throughout the flowering season.
Some good varieties:
Black Caviar FireStar
Per-Fyoom Perfume Double Knockout
Gold Bunny Iceberg
Or choose smaller rose varieties such as:
Bees’ Paradise Pink
Hot Pink Bonica
POTTED ROSES AVAILABLE FROM SEPTEMBER
SPRING ROSE CULTURE NOTES
Fertilise in early spring with Neutrog Sudden Impact for Roses. Follow the manufacturer’s instructions. As the soil should be damp from spring rains, try and apply prior to forecast rain, then no “watering-in” will be necessary.
It is important to water your roses with one good soak per week as the spring weather becomes drier. Assuming the roses are mulched, the established rose plant requires 20 litres of water in one application per week if the average maximum temperature for the next 7 days is in the range 20 – 30˚C. If the average maximum temperature for the next 7 days is in the range of 30˚ – 40˚C, the rose will require 30 litres of water in one application that week. Roses in their first year may require supplementary water in addition to that described above as their roots are not fully established and the young plants can dry out more quickly than well-established plants.
PESTS AND DISEASES
As rose shoots get to 15cm in length, apply preventative fungicides to avoid bad infestations of black spot, rust and mildew. A couple of sprays, a fortnight apart, mid to late September and early October may be required. Avoid using strong pesticides on Aphids and Grubs, instead try Organic oils such as Eco-Oil or Eco-Neem or one of the natural sprays (such as Natrasoap) to control bad infestations. You can also wash off Aphids with a spray of water.
Knight’s Roses recommend Neutrog’s ‘Whoflungdung’ which is a certified organic mulch, biologically activated, nutrient rich and weed free. While it can be applied immediately around the base of mature roses (3 years and older) it is advised not to apply mulch closer than 15cms to new, one or two-year-old plants as sometimes damage can occur to young basal shoots. ‘Whoflungdung’ comes in 20kg compressed bales. Apply water after application to settle the mulch in. Mulch significantly reduces evaporation, saving up to 40% – 50% of the irrigation otherwise required; it cools the root zone and introduces good microbial activity into the soil.
A FEW BASIC RULES FOR GROWING ROSES IN POTS
- Choose a location which receives at least 5 to 6 hours of sunlight each day. The advantage of growing a rose in a container is that you can shift it to ensure it is in the right position for sunlight. Courtyards which are open to full sun every day can get very hot in summer, often 10 degrees Celsius higher than the forecast temperature – it is suggested that some afternoon sun protection is advisable during heatwaves.
- Ensure the pot can be shifted. This can be achieved by having the pot on a low stand with wheels or to fit a sack truck under it for easy relocation. Mark the side of the pot which faces north and when you relocate it ensure that the pot is placed to face the sun in the same position.
- Container Size – the bigger the better! But as a general guide miniature roses or patio roses need a minimum 10 litre container, while a bush rose needs 20 – 40 litres – depending on size. Half wine barrels make excellent containers for roses but shifting or repotting roses grown in such a large container can be a challenge. Terracotta clay, concrete or wood containers work well as they do not absorb heat like plastic pots – particularly black plastic pots which should be avoided.
- Choose the right potting mix. It must be a premium mix with the 5 ticks for Australian Standard certification. It should be free draining but retain moisture. Ask your nursery to ensure you get the correct mixture. Roses should be repotted with new soil, every 3 to 5 years. Winter is the best time to repot your rose plants. Clean pots as disease can spread easily in dirty containers. Add some Neutrog ‘Seamungus’ pellets into the mix.
- Roses in ports require regular watering, the oil must reamin moist and cannot be allowed to dry out. Water the pot until water is seen to be freely draining through the holes at the base of the pot, then cease watering. The drainage holes cannot be allowed to block up as roses hate ‘wet feet’. If the container is the right size for the rose it will need water 2 to 3 days per week in the summer and maybe daily during heatwaves. Watering can be reduced to 1 to 2 times per week at other times. You can put your finger in the pot to test dampness. If your finger comes out clean the soil is dry.
- Fertilising is another important element. Feed the roots with a few Neutrog Seamungus pellets and Neutrog Sudden Impact for roses pellets lightly scratched into the top surface. These break down slowly over 4 to 6 weeks constantly feeding the potted plant. They then can be replenished every 6 or so weeks. Sudden Impact for Roses is also available in a liquid form and its organic base provides a full range of nutrients in a slow-release form, while the water-soluble nutrients have been added to maximise performance.
- The final point relates to pests and diseases. Potted roses can often get spider mite and to avoid this, thoroughly wet the foliage (both underneath and above) with a strong stream of water every 7 to 10 days. Similarly, aphids can be washed off or rubbed off the foliage. An occasional spray with Eco-oil or pest oil will control fungal problems and help with insect control.
YOUR QUESTIONS ANSWERED
Q. 1. What causes proliferation in roses (aka vegetative centre) and is it harmful to the plant? How do you prevent it or treat it? Are some varieties more prone to it happening?
No one is really sure what causes vegetative centres. Certain varieties are more prone to it than others and it generally occurs when the rose bush is in a rapid growth phase e.g. the first spring flush. Generally, the rose does not have a repeat occurrence in the same season and the problem does not spread to nearby plants.
Q. 2. Please advise about soil additives to prevent fungus in container roses, so that we can save the plant from black spot and die-back disease.
From our experience, “die-back” does not occur in well ferterlised, healthy plants with good growth. Die-back can result from sunburn on immature stems or from a grub burrowing into a stem. Black Spot spreads by spores from the Black Spot Fungus (Diplocarpon rosae fungus). These spores can be spread simply from one leaf to another as airborne spores or by a raindrop hitting a spore on the ground which then bounces up onto a leaf. Once a leaf is infected with Black Spot, it will die and drop. Prevention is better than cure and use two applications of preventable fungicides early in spring to protect young susceptible foliage. WE like to use organic preventable fungicides, such as Eco-oil.
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