Silver Torch or not???

[aimeekinsey]

Could someone please tell me if i'm correct or not in thinking that the large cactus in the window box is a silver torch? I got it from ikea a few months ago along with the grafted cacti to the right of it also in the window box, it was the same size as them and it has grown considerably since i put it in some cactus compost. It's roughly 12 inches in height and i've read that they are mature at roughly 18 inches(if i've identified it right), could anyone also give me some advice about fertilization in order to encourage flower growth in the summer months? Many thanks

[iann]

Maybe you misread 18 feet as 18 inches? 18 feet might be a stretch for Cleistocactus strausii, but certainly 10 feet. They don't branch but they do they clump from the base. However, you have three (four?) separate plants of and they're a long way short of mature. They can start to flower at 2-3 feet tall in good conditions. They don't need a lot of heat but they do need a lot of sun to do well. They like regular summer water, but not sitting in soggy soil for long periods. Dry and cool in winter, frost hardy.

[Rod Smith]

I don't agree entirely with Ian's comments. My C. strausii flowered this year at 10 years old and 18 inches high. I lost the tops of my two tallest stems through withering due to lack of water in the winter and the flowers came on the stem that had withered, just below the withered section that I had cut off. This species is apparently prone to this so as yours appear to be kept indoors they will definitely need occasional light watering during the winter months. Fertilising is beneficial in the summer at every 2nd or 3rd watering. They need as much sun as you can give them in order to flower.

[iann]

Good news! Plants with dead tips should quickly sprout at the base, sometimes several stems at once.

[SnowFella]

Mine did the odd thing and restared growth at the tip after some pesky critter chewed the whole tip off.
Now a healthy near 3 foot plant with no hints of flowering or sending up new stems.

[cactushobbyman]

These pics are from 2-2012 for the tall one, 1-2013 for the small one. The one in full bloom about 8 feet, the other 2+ feet. The tall one did not bloom until about 2008???? The tall one was planted in that spot about 16+ years ago. The small one, 2-3 years in that spot,. and was a gift from my son in a 4 or 6 inch pot. Plastic of course. Outside full sun 100+ degrees in summer, and down to high teens in the winter. I put cups over the tips in winter.

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[Mr Monopoly]

These pics are from 2-2012 for the tall one, 1-2013 for the small one. The one in full bloom about 8 feet, the other 2+ feet. The tall one did not bloom until about 2008???? The tall one was planted in that spot about 16+ years ago. The small one, 2-3 years in that spot,. and was a gift from my son in a 4 or 6 inch pot. Plastic of course. Outside full sun 100+ degrees in summer, and down to high teens in the winter. I put cups over the tips in winter.

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Man I envy you Californians...

[DaveW]

I agree with Rod, my Cleistocactus strausii started flowering as a single stem from seed about 18 inches high in my greenhouse bed in the UK. It was growing about 4 inches a year at that time too. Though Ian is correct in a way since with all plants some individuals of a species will flower earlier than others, also seed collected from some populations in the wild may produce plants that flower much smaller than others. Mine has a BLMT number so was seed originally collected in habitat by Brian Bates.

One problem I find with them like Rod is the main stem will often stop growing and it starts to offset around the base, growth not always starting from the main stem again later. However a friend of mine had one 6ft high in a comparatively small pot and it's main stem had never stopped growing, but his greenhouse was kept warmer than mine in winter. Maybe it's our growing conditions Rod, or just plants from different sources having different characteristics?