Help your roses beat the heat


The Citizen (KZN) - - City - Lud­wig Taschner Build strong roses Keep leaves healthy Keep groom­ing

A bucket of wa­ter twice a week per rose de­liv­ers 10 to 20 litres, which is ad­e­quate.

In­tense heat, hot nights, and late rains that are a week or more apart. Is this the new nor­mal for grow­ing roses? The heat has speeded up re­flow­er­ing. I have no­ticed that it takes only a month from cut­ting back to new blooms, com­pared to well over two months from win­ter prun­ing to the first flush.

How does that change the way we grow roses?

Fer­til­is­ing is even more im­por­tant than be­fore, oth­er­wise the roses will quickly be­come starved of nu­tri­tion, which af­fects their growth and flow­er­ing.

Once a rose has pro­duced flow­ers it prefers to go semi-dor­mant, pro­duc­ing hips (fruit) and slow­ing its growth for the rest of the sea­son.

The con­tin­u­ous avail­abil­ity of nu­tri­ents, cou­pled with wa­ter, en­tices the rose to keep sprout­ing new shoots and flow­ers. Do not ne­glect the monthly ap­pli­ca­tion of Vig­orosa.

The hot days, es­pe­cially those up to 31ºC, in­crease the tran­spi­ra­tion rate and evap­o­ra­tion from the soil.

Giv­ing more wa­ter in a time of wa­ter short­ages doesn’t seem like a re­spon­si­ble re­sponse. How­ever, there are ways to get wa­ter to the roots:

In be­tween rain­fall, har­vest grey wa­ter from the shower and bath. A bucket of wa­ter per rose twice a week de­liv­ers 10 to 20 litres, which is more than ad­e­quate.

In­vest in a 5 000-litre rain­wa­ter har­vest­ing tank. One good down­pour can fill a tank.

If the roses are suf­fer­ing from root com­pe­ti­tion, dig them out and plant them in pots. Ei­ther sink the pots back in the ground or grow the roses as con­tainer roses.

They must be wa­tered ev­ery day in this heat, and that is where grey wa­ter comes in. Wa­ter from the kitchen, used to wash veg­eta­bles or as rinse wa­ter can be used.

Mulch around the roses with a one to two cen­time­tre layer of mulch. It re­ally does keep the soil moist for longer.

One side ef­fect of the heat is bad in­fec­tions by thrips.

Chilli thrips is a par­tic­u­larly vi­cious type that de­forms buds and leaves and has a rapid breed­ing cy­cle. It takes only a week or so from the lay­ing of eggs to two stages of lar­vae and new adults ready to lay eggs.

Gar­den­ers who pro­tected their roses by drench­ing with Koinor or its equiv­a­lent are not ex­posed to this prob­lem. The drench­ing can still be done.

Badly in­fected parts of the roses are best cut off, put in plas­tic bags and thrown away. Spray­ing with Plant Care pro­vides im­me­di­ate re­lief for the roses.

When the rain does come in the form of drench­ing all-night rain­fall, the next prob­lem is black spot, which oc­curs when leaves are wet for at least six hours.

Spray as soon as the rain stops with the fungi­cide Chronos that pre­vents de­fo­li­a­tion caused by this dis­ease. The spray is ab­sorbed by the leaves within min­utes and can­not be washed off by sub­se­quent rain.

If one wants a show of roses for Christ­mas now is the time to cut off dead flow­ers and even un­der cut stems that have sprouted al­ready.

ROSE OF THE MONTH. Im­pala (Korstern­fue) has won awards in Euro­pean Tri­als. Im­pala is a flori­bunda that flow­ers freely, grow­ing into a dense chest-high shrub.

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