Summer Cultural Notes

Roses are hardy plants and will stand a reasonable drought situation, but they will not thrive unless the soil remains moist. If the soil gets too dry they may sulk or even stop growing. Constant moist, not water logged soil, is of the utmost importance. It is difficult to supply too much water if the drainage is adequate.

How much water is needed? This depends to some extent where you live, how hot during the summer months, dry winds, humidity etc. In the NW Sydney region, a general guide is around 15 litres per bush (or per sq. metre). This amount is applied on a weekly basis during summer. If any rain falls accept it as a bonus.

Moisture meters are available at most good nurseries; these give a general guide. You could also push a rod in the soil in various locations and note the dampness of it. This is particularly effective in clay soils. These are some ideas to make a reasonable judgement.

Very porous or sandy soils will require the same amount of water a little more frequently than heavier soils. It will also take less time to saturate the area. Cease watering if any seepage is visible from your beds, this is a waste of water, and leaching of nutrients.

Keep a rain gauge in your garden (a good Christmas present), check the gauge regularly, this way the exact amount can be recorded; you can regulate your watering accordingly. A reading of 40mm on the gauge equals approximately 15 litres.

Remember, weekly deep, penetrating watering is much more beneficial than frequent light sprinkling.

Roses grown in pots require much more attention to watering than field grown roses. The problem is that container roses in our climate are vulnerable to heat stress. Temperatures may soar as high as 50 degrees Celsius in pots exposed to “BLOW TORCH” full sunlight.

The greatest way to reduce heat reduction is afternoon shade. A bonus of shade is that it gives heat relief to the whole plant, not just the root zone. Using lighter coloured pots rather than black pots will also help. Pots grouped close together can also buffer some sunlight.

In my own garden I use pot in pot where possible, I also group small miniatures onto one large container to help shield the sun’s rays and conserve moisture. Try not to stand the pots on hot sealed surfaces such as concrete.

Thrips, small elongated insects about 1mm in length are pests of a wide variety of plants. The most serious damage to roses results from the thrips entering the opening buds and feeding on the petals, causing disfigurement of the blooms. Severe infestation will bruise buds to the extent they will not open. They feed by rasping away the surface tissue and sucking away the sap from the petals.

Bud and bloom spot coverage is good (if preparing for a show) in spring time. Recent research suggests thrip control should include good spray coverage of the entire plant as well as the rose beds. Weekly spraying is recommended during the thrips’ season. Any spray material (even water) can damage pastel colours (thrips’ territory) when applied on hot days. Spray early if possible or spray late for best results.