The spikes of life

As if their ar­mour isn’t enough cac­tus also pro­duce strik­ing flow­ers

NewsMail - - GARDEN - with Ma­ree Cur­ran Got a gar­den­ing ques­tion? Email ma­ree@ede­nat­by­ron.com.au

WE USU­ALLY ad­mire cacti for their in­ter­est­ing shapes and some­times vi­cious spikes. But in spring, many cacti also have re­ally pretty flow­ers. Each flower usu­ally lasts a few days, clos­ing in the evening and open­ing again in the morn­ing. Plants can pro­duce dozens of flow­ers, so the flo­ral show can last for sev­eral weeks.

In the nurs­ery, we of­ten see na­tive bees vis­it­ing the flow­ers. Cacti have adapted over the mil­len­nia to sur­vive in the harsh­est of en­vi­ron­ments. Most have spines in­stead of leaves be­cause the smaller sur­face area greatly re­duces mois­ture loss through evap­o­ra­tion. The spines also pro­tect the cac­tus from preda­tors such as birds.

Most cacti are colum­nar or glob­u­lar (spher­i­cal), pro­duc­ing a low sur­face area-to-vol­ume ra­tio, thus re­duc­ing water loss, as well as min­imis­ing the heat­ing ef­fects of sun­light.

The ribbed or fluted stems of many cacti al­low the stem to shrink dur­ing pe­ri­ods of drought and then swell as it fills with water when it be­comes avail­able. There are some cacti that look like lit­tle mounds of peb­bles, and oth­ers that have spines so long and sharp they are pos­i­tively scary. Some of the spines have hooked tips, and some are so fine that they are fuzzy rather than spiky. They are ar­ranged in per­fect geo­met­ric pat­terns over the cac­tus – quite mes­meris­ing when viewed in close-up.

Cacti can be small, only a cen­time­tre or two in height, to large at more than 15 me­tres tall. They don’t need a lot of care so they are per­fect for the time-poor gar­dener.

A sunny po­si­tion is best, even a sunny win­dowsill in­side is okay. Cacti will do best if they are in a po­si­tion where they re­ceive good morn­ing sun but are pro­tected from the worst of the mid­day heat.

A cac­tus has a shal­low, spread­ing root sys­tem, al­low­ing the plants to cap­ture as much of that scarce desert rain as pos­si­ble.

Th­ese adap­ta­tions al­low cer­tain cacti to sur­vive three years with­out water so make sure you water th­ese plants spar­ingly. A cac­tus that is over­wa­tered is much harder to save than one that is un­der­wa­tered.

Cacti and their cousins, the suc­cu­lents, work well as pot­ted plants, and can co-ex­ist hap­pily to­gether in the same planter. Be­cause of their shal­low, spread­ing root sys­tem, a wide shal­low bowl is more suit­able than a tall nar­row pot. Make sure you use a pot­ting mix spe­cially for­mu­lated for cac­tus and suc­cu­lents.

When han­dling spiky plants, pro­tect your­self by wrap­ping the top in news­pa­per or bub­blewrap and wear­ing gloves and long sleeves. Use a small paint­brush to re­move de­bris that may be trapped between the spikes.

Feed them a cou­ple of times a year with a slow re­lease fer­tiliser, or use a liq­uid ev­ery few weeks.

CAC­TUS FLOW­ERS ARE POL­LI­NATED BY IN­SECTS, BIRDS AND BATS. NONE ARE KNOWN TO BE WIND-POL­LI­NATED

PHOTO: CON­TRIB­UTED

A cac­tus flower in full bloom is a stun­ning spring dis­play.

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