Plenty of sunshine and water (spring and summer) will do it. I have never actually applied a fertilizer to my cactus and they grow very well here outside. Even in pots, they do well. Just make sure you have them in a quality soil mix. Red

Outside in the ground you won't need to fertilise. In a pot you will need to fertilise, either by repotting every couple of years into a fresh soil which includes fertiliser, or by using a dilute soluble fertiliser. Generally a cactus fertiliser should be relatively low in nitrogen and used 2-4 times more dilute than recommended for normal plants. Some people use fertiliser with every watering, at maybe 5 times more dilute than normal. A lot depends on your soil. You are much more likely to over-fertilise than under-fertilise, burning the roots and potentially killing the whole plant.

Lastly and most importantly, you won't make your cacti bloom by fertilising them unless they happen to be in extremely old depleted soil or a completely nutrient-free medium like haydite or coir. Cacti flower when they receive sufficient warmth, sun, and water during their growing season, possibly combined with a cool dry dormant period, and only when they are mature enough.

I have found that using a high phosphorus fertilizer (like 15-30-15)is very helpful in getting cacti to bloom. The amount of fertilizer used depends on how much light the plant gets and the other growing conditions. Mine are outside all year around in full sun, so I fertilize rather heavily. Virtually all my plants bloom. However if you are growing your plants indoors on a windowsill, I would only use a very dilute solution once a month.

Keep in mind that other factors like a dry winters rest is helpful in getting many cacti to bloom. Also unless a plant gets very good light, often no amount of any type of fertilizer will make it bloom.

I have a crown of thorns I've toted around for 30 years.
It's a booger to repot so I haven't for about 5 years. I use a generic brand of house plant fertilzer mixed very weakly and the darn thing blooms for months at a time twice a year.
I let it get real dry before watering. It is inside.

hi .what time is the best time to fertilize cactus?

I have found the best fertilizer for me is tomato fertilizer, half strength of whatever is stated for tomatoes. Best time of year to fertilize is during their growing season.

I have a couple of huge Opuntias, 3-4' in diameter, that grow year round (Zone 3)outside in the ground and bloom profusely every June. The only fertilizer I give them is a good dose of bone meal every Spring.

just curious if a water soluable 2-7-7 fertilizer would suffice for a newly planted cactus cutting. I'm not too experienced in cactus growing.

please inform me, Thanks
BEAR

Hi Bear,

You accidentally stepped into an old place, where folks don't post much, the Photo Gallery. Better to post this at the more currently used site called 'Discussions'.

Short answer, a newly planted plant doesn't need fertilizer, assuming the mix is new (& not recycled) & what kind of mix it is, it will still have some nutrients for a short while.

Also, since you say you're somewhat a cactus newbie, cacti don't require as much fertilizer as other plants. Some of us who grow cactus &/or succulents barely use fertilizer at all, depends on which plants & which mix.

I'd hold off on the fertilizer another few months, then only do it when the plant is in active growth.

i feel guilty for my cactuses. summer out/ winter in, no ferilizer. shame on me.

i do not know the name of my cactus but it did flower this summer, first time in my life that i did have something like that, i was happy.
I should do something more to my cactuses; talk to them more often, fertilize them, transplant them, etc.

i have no photos but i would like to know what kind are they so I can talk to you ppl and ask more questions.

Chatting with a cactus ?