I can't help with greenhouse nurseries in St Louis but a stop at the Missouri Botanical Gardens is a "must". It's one of the best I've ever been to and I go each time I'm in St Louis.

I just opened a Houseplant store in St. Charles last week. We have lots of tropicals! St. Charles is just on the other side of the river from St. Louis. Take a look at my website - later on this week I will be posting a picture of the store. Our name is O2 Houseplants at 510 North 5th St. in St. Charles, MO.

www.o2houseplants.com

Here is a link that might be useful: ST. CHARLES HOUSEPLANT STORE

I also love the Mo Botanical Garden. Their giftshop plant offerings are limited but they always have bonsai and now have lots of orchids. Loads of info here: http://www.mobot.org/gardeninghelp/plantinfo.shtml
Their master gardener answer service phone line is staffed by very knowledgeable people (volunteers I believe) who can steer you to some in the direction you might be going.

A few of my favorites (close to my home) are:

Summer Winds/Timber Creek (2 locations in the metro area) http://www.summerwindsmo.com/

Ahner's on Manchester Rd just east of Hwy 270 is great. http://ahners.com/

Sugar Creek is also close but is more for outdoor plantings. http://www.sugarcreekgardens.com/

There are many more very nice nurseries in this area. Have fun shopping!

Thank you so much for the Mobot idea and website. Great idea also to call the volunteers. I will do so. I'll also be checking the websites of the other nurseries--thank you thank you thank you.

Jennifer, can I get to O2 by public transportation? Looks great. I'll be staying at the Adams Mark, if that means anything to you.

I live in Wisconsin now, and moved here 3 years ago from St. Louis. The Adams Mark is a long way from O2 in St. Charles -- more than a 1/2 hour drive if traffic is good. You could take a taxi but it would be a high fare, probably more than $50.00, especially during a time of heavy traffic. It's possible to take a city bus, but it would take a long time. Not much from a floral/garden perspective to choose from in downtown St. Louis(location of the Adams Mark). I recommend Ahner's for houseplants/tropicals. But it's on Manchester Road in Kirkwood/Des Peres, about a 20 minute drive from downtown (location of the Adams Mark). The Missouri Botanical Garden is about a 10 minute cab ride from downtown. It's one of the leading botanical gardens in the world, and has an amazing collection. Not really any plants to purchase (though the Garden Gate Shop is very nice), but you can see lots. I highly recommend it. I've placed their website below.

Here is a link that might be useful: Missouri Botanical Garden