Here's another site for reference:
http://www.squawmountaingardens.com/tabs2.cfm?CID=4&tab=%27aSempervivumsThis spectacular group of plants is commonly known as 'Hens & Chicks' or 'Houseleeks'. They are European in origin and are mostly hardy to Zone 4 They exhibit a profound ability to survive dryness. These plants display a dazzling show of progressive color changes throughout the year. The species cross readily, resulting in the fantastic collection of hybrids we list. Soil and light conditions will alter the plant color greatly, so take care not to overfeed Semps and provide ample light for them. In areas of the country where extreme summer temperatures are experienced, some light shade is beneficial. Semp sizes are roughly classified as follows: Mini- up to 1/2" Small- 1/2" to 2/1/2" Medium- 1 1/2to 2 1/2" Large- 2 1/2 and larger HC indicates that variety holds color. WC means the variety has good 'winter color'.
http://www.squawmountaingardens.com/product.cfm?CID=13Jovibarba Heuffelii:
This gorgeous species of Jovibarba is unusual in that it does not produce it's offsets on stolons. Vegetative propagation may be achieved only by splitting the main stem with a sharp knife. The plants form very tight clusters of enchanting rosettes and are generally hardy to Zone 4 Both the species and the hybrids are listed together here.
Sedum & Sempervivum Garden culture
Sedums and Semps are versatile and useful plants that lend themselves to a variety of garden situations. They are both delightful in rockeries. Sedums work great around stepping-stones. Areas that often are passed over because they are "difficult" will lend themselves beautifully to these little charmers. They make beautiful mosaics to take the place of lawn.
Some sedums seem to do well, or even better, in the shade, so one is not limited in situation entirely. For the most part, however, they all need a lot of light, but not necessarily full sun. We have grown them in full sun in open beds with success, but even here we get days of 90 degrees to 100 degrees and some varieties will burn a bit. They do survive, however.
Good drainage is a must. If your soil tends to be heavy, you may need to add coarse sand (not builders sand, or pumice- this floats to the surface, or fine gravel). If your soil is light or summers are hot and dry, add some peat moss or extra humus.
These are mainly alpine plants so most species like a blanket of snow in the winter. Some hybrids may need more protection from severe freezing, but will usually survive.
Many people who have been "bitten" prefer to grow their collections in containers. Usually a 6" pot is used. Side drainage is desirable, but not essential. Do not cover drain holes; leave them free.
A good potting mix can be bought at nursery centers or you can mix your own. I do believe there are as many mixes on the market as there are growers. Just be sure it's light and free draining. Our mix is made up of fine bark, peat moss, and pumice. Coarse sand can be added to this. Many prepared mixes have a commercial fertilizer added, but these will be active for only about six weeks. The addition of bone meal will give them something to go on. Addition of slow release pellets may be used as well.
Wind seems to be something of a problem. Where we're located we get nasty east winds that suck the life out of everything. The freezing winter winds are our worst enemy, but we've had people from other areas of the country tell us of trouble from drying winds in summer. It may be well to provide temporary shelter for choice collections.
Our plants are grown in alpine houses. These are covered with poly in the winter to protect them from the weather. In summer we take the poly off and cover the houses with 30% shade cloth. This is enough shade for us as it allows plenty of light and air circulation.
Propagation of Sedums and Semps is simple. With Semps a single rosette or offset is all that is needed. The base of the rosette should be in contact with the soil, don't plant it; just set it on top of damp soil and stand back. Many Sedums will start from leaves, all from stem pieces, or root divisions. When you receive plants that appear to have broken apart, scatter these bits and pieces on a pot, press them down gently and they'll grow for you.
Jovibarba heuffelii need a different procedure for propagation. These plants do not produce offsets in the usual manner, but form directly from the crown of the main root. Once in a while they will divide themselves, but usually the best thing to do is to cut these rosettes off. Use a sharp knife and cut so that each new plant or rosette has a piece of the main root on it. Dust this with a fungicide and place in moist soil. Sometimes we let the cuts dry for a day or so. This seems to work well.
Semps will die after blooming, but not to worry. They don't bloom for 2-3 years and in the meantime you've gathered generations of "chicks" to carry on. It is useless to try and stop the process by cutting off the bloom stem. Nature is wonderful and has a way of doing her own thing.
You'll find infinite color, form and character in these plants. Many Sedums growing in starvation conditions produce vivid color. Many are at their best in the spring while others provide lovely winter color.
In summary, good drainage, air circulation, light shade, and a measure of imagination will bring great returns.
