CactiGuide.com

Hello everyone,

I was wandering through different resources and mostly found that for good spines growth cactus need a lot of sun (at least 5-6 hours). I didn't find anything else what could help. In my case my cacti grow inside and has around 4 hours of afternoon sun. I noticed that spines are not so thick and well developed as it should be.

E.g. Last year I bought Ferocactus rectispinus, his spines were thick and close to 5cm long (2 inches), during growing at my place spines decreased almost 2 times - half thickness and length close to 2-3cm (1 inch).

Ferocactus townsendianus stem is pretty big, it grew at my place for a while. As you know spines should have started becoming much thicker however they are still pretty thin.

Echnicactus grusonii also produces wicker spines than expected (last year I put it closer to Ferocactuses but it started getting burns so I had to move it to light shade)

Similar issues I have with Lobivia korethroides, some Mammillarias, some Notocactuses.

However Gymnocalisiums, Echinopsises spines are developing well.

I regularly repot and fertilize, roots are in a good shape.

I've even bought a special growing lamp which producing around 20k lux for 8 hours of additional light in the morning.

I would really appreciate some hints

Nothing can substitute the sun. Ferocacti aren't good choice for indoor growing. These guys need much space, light, air. I hold them all summer in polycarbonate greenhouse which is probably the best solution - they don't burn and spines grow larger than in southern nurseries. Here, in latitude of 61. Though I use some shadings with very light old curtains from may to july.

I think heat may also have some influence, which could explain why they do so well in the greenhouse - it traps heat.

PS But my plants are probably very poor from the viewpoint of those who grow own plants outdoors all year round somewhere in Mediterranean or SoCal.

Thanks a lot!