How to make Cacti flower

Hello all,

I have a few cacti and would like to see them flowering. I grow them under horticultural LED lamps with a daily ON period of about 16hrs using a timer. The cacti grow very quickly but I haven't yet seen any flowers. Is there a technique to force flowering using light patterns or watering (pictures of my cacti below).




Thanks for your patience.

Ademission

 

I think you are being too kind, desert cacti are very seasonal and need a dry resting period usually with lower temperatures, lots are timed to flower in spring or early summer, others like summer downpours with long dry spells in between.
Would you grow a hardy tree under these conditions, probably not, but it might work with tropical plants.

Some cacti may be possible grown like this but not the majority its very unnatural..

 

I agree with @pete it isn't the right way to grow cacti.
You say they grow quickly, but cacti need to grow slowly. If they grow too quickly they'll get soft and will be likely to rot. Why can't you grow them on a sunny windowsill or in a cold frame ?

 

Hello Pete, Michael Hewett

Ok, I think I understand what you are saying.

I've adjusted the daily amount of light down to 12hours. I'll adjust the lighting period downwards again in a month or so to 8 hours. I will also water them less frequently (instead of once every 2 weeks, I'll change to every 4 weeks and then further to every 6 weeks for a while until next spring when I'll reverse the process.

Unfortunately I cannot adjust the temperature downwards as the pots are not heated in the first place (cacti at room temperature). I have 2 greenhouses but they are not heated and I suspect they maybe too cold in winter for cacti (what's your opinion)?

Do you think the above measures will help to get them to flower?

Best regards

Ademission

 

It might possibly work, different cacti come from different parts of the world, obviously.
Some see frost and snow most years, some dont get very cold at all, they all have differing things that spark off the flowering but I think most do need the resting period, some actually shrivel considerably in the wild while waiting for rain and only then will they flower usually profusely until they get dry again.
Most need to struggle at least bit to flower well in my opinion.

 

I grew some in a greenhouse in the garden when living in Leicestershire, most flowered within a couple of years of planting, I had a prickly pear almost 5 feet tall. Covered with bubble wrap in winter if frosty or snowing and fed sparingly in the summer. Only problem was weeding the bed, a painful chore.

 

Cacti are a large group of plants found from Argentina up into Canada so they are very varied in their requirements when it comes to flowering.
Some need to reach a certain size before they flower and others need to reach maturity; on this basis some of mine are never going to flower others flower every year. I have one that flowers throughout the summer with flushes of white flowers each lasting a day.
The one thing they don't like is damp, cool conditions. Most of mine come in onto a windowsill over winter, some are too large too fit on a windowsill and these with any with mealy bug get left in the greenhouse unwatered and generally come through okay.
A lot of cacti will take -10°C and lower if dry so many of yours will be alright in your greenhouse over winter.
Echinopsis can flower within 18 months of sowing seed and there are many hybrids, bred for flowers, available.
Your indoor setup looks ideal for growing epiphyllums and their relatives, these live in jungles in tree branches so free draining organic material, fairly high humidity and moderate temperatures all year round, consistent light levels and fairly stable day length.

 

I agree Epiphyllum's are a great flowering succulent, I have several colours, one thing they need to flower is to be pot bound.
Epiphyllum by tigerburnie, on Flickr

 

My cacti get watered and fed heavily in april, maybe again in june, a light splash in august then probably nothing at all for the rest of the year