Questions about Pruning, Feeding Hibiscus

We have about 8 of the large "frisbee" hibiscus, deep red, in our back yard in Columbia SC (zone 8). They have done real well, but seem to go through cycles where the buds die before they bloom, leaves turn brown, and the plant looks unhealthy. I had a plague of white flies attack two or three of them. I now believe I have gotten rid of them (with Safer's Soap). Is it a good idea to cut these plants back periodically? One plant nearly died when we uprooted it to move in another tree behind it. I cut it back half way and it grew back healthy and full of blooms in no time. I'm wondering if similar treatment would help those that are looking bad, as described above.

Regarding feeding: what is the most effective plant food and how often do these plants need to be fed. My landscaper told me every month or so when they are blooming that I should spray or apply granular fertilizer. I'd like some more specific advice of what kind to use.

I love these plants; they are so exotic looking and I love the fresh blooms that come up again and again.

Sounds like you have the hardy ones and yes, they do get a bit raggy but like you have already found out, they pop right back when you prune them. They will probably lose all their leaves around the end of October.
I am a bit of a fanatic about this but - worm castings naturally repel whiteflies in hibiscus and many other plants. A good layer of them under the drip line will pretty much eliminate them.
Since you like the hibiscus, I hope you have the fall bloomer H.mutabilis, the Confederate Rose. They are probably about to bloom (if they aren't already) in Columbia and nothing is prettier this time of year.

Where does one purchase worm castings? What exactly are they? I'm willing to try anything. The white flies are now gravitating to my lemon tree.
I'm interested in the Confederate Rose and will look into getting one, or two. Sounds nice, especially if they can offsett the fading hibiscus this time of year.
thanks
--Don

HVH sells them, I believe.

See this page: http://www.hiddenvalleynaturearts.com/acatalog/wormcast.htm

Castings are worm poop. Completely odorless and an excellent WF deterrant. I also use it on my tropical hibiscus that I bring in the house. You can call the nurseries and ask about it or order it on eBay. The shipping is high but the total comes out to the same amount I used to pay when I bought it in Charleston.

This is who I bought from:
http://cgi.ebay.com/Worm-Castings-Organic-Fertilizer-15-lbs-fast-ship_W0QQitemZ170150820049QQihZ007QQcategoryZ20540QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

You could check the Market Bulletin (SC Dept. of Agriculture) for someone in the Midlands selling the Confederate Rose.

ifyou are on the Lexington side of columbia, then you should check out wingard's nursery. when i lived there, that was my favorite place to go. also, a lot of the farms and old houses have them in their yards. you could maybe stop by and ask some random person for cuttings... i got mine from the Greenery down here, and its already got buds!

Diehrd and doyle, here is the link for the market bulletin.

http://www.scda.state.sc.us/marketbulletin/backissues/backissues.htm

You can view back issues for free on line and most of the listings stay the same issue to issue. You want to go to the "Plants and Flowers" section. Sometimes "Garden Plants" has some things of interest too but they are mostly fruit and veggies. There are a number of places in the midlands that have Conf. Roses in the last issue and these are all backyard growers selling their excess. Really inexpensive and fun to meet some of these growers! They are also generous, you generally come away with much more than you buy.