looks like a Pilosocereus

weekly is a lot of watering. That pot has holes in it for drainage?

Yea, I thought so too. I've killed a few plants from over-watering, so I'm trying to ID this so I can adhere to the best schedule for it.

The pot didn't have any drainage holes, but I drilled 5. I added about 3'' of pebbles at the bottom and mixed perlite in with the cactus soil to help with drainage. I'm hoping this works.

These need as much bright light as you can give them. A south facing window would be best. Always use a pot with drainage, preferably unglazed terra cotta.

Words of advice,..never take the word of a nursery or BBS employee regarding plant care, as many times they have little knowledge of the particular plant. Also, never water on a schedule. Water only as necessary. But I do not water my cacti at all in winter. To do so can cause the plant to start week and spindly growth, a condition known as etiolation.

Christopher

The three inches of gravel at the bottom does not increase drainage. That is a myth. Take your cactus soil and mix it with equal parts of perlite, pumice crushed grantor some form of grit. That is how you will increase drainage . Put a screen over the bottom of your pot.

If you want to try researching the ID yourself . It is all about legwork. somewhat boring but try it.

Here is a link that might be useful: IDing by habit on CactiGuide.com

wantonamara - I can't say I agree with you about gravel at the bottom of a pot. If you are using any type of soil or finer materials (such as those in cactus mix) in your potting mix, gravel (or pebbles as was mentioned above) can keep the drainage hole from getting clogged up.

Ehun, actually the fines will settle in between the larger stones and soon clog all the holes. Think of it this way, if you have a cylinder of the same sized objects, the gaps will always remain. Once you add smaller particles, they settle in between, going to the smallest crack they fit. Once the process starts, increasingly smaller cracks will accommodate the smallest particles. It does not happen all at once, but after a year or so of watering, the settling really shows.

I found this:http://www.sustainable-gardening.com/how-to/tips/drainage-in-containers

And this about a perched water table etc.:http://www.todayshomeowner.com/garden-myth-putting-gravel-in-pots-and-containers/

This myth of better drainage refuses to die, along with the widely held myth that water drops burn leaves. Life goes on.

I can see that, Dzitmoidonc - thanks for the additional info.

I have never personally heard anything about water drops burning leaves but it sounds kind of ridiculous...

-EHuns