Fall is normally the best time because roots on a new plant need help establishing themselves. The shallow root system can't take in all the water it may need to survive and a drought can spell disaster. Water them frequently in the morning. Mature plants are much hardier and Mother Nature seems to take good care of them under normal conditions. When transplanting a large plant several steps should be followed. * First, it is best to stimulate a tight root ball by root pruning the plants to be moved about a year before moving. This is accomplished by cutting a circle around the plant with a shovel to cut off roots that extend beyond where you will be digging when you transplant. This radius is usually slightly smaller than half way to the drip line. If you can't do this you will need a larger root ball, probably almost to the drip line. * Second, it is best to move when the plant is dormant and not stressed. This would be in the spring or fall when the plant is still dormant but the soil is not frozen. Moving in the fall before the ground freezes is preferable if you don't have a problem with frost heaving. Sometimes winter freezing and thawing cycles can actually lift a transplanted plant out of the ground where the roots are then desiccated and the plant dies. For this reason, it is safer to transplant in the spring after the ground thaws in climates where frost heaving is a problem. * Third, take precautions to preserve the integrity of the root ball. Tie the ball together and support it so it doesn't fall apart. The very safest approach is to dig a trench up to 12 inches deep, around the dripline of the plant. Then undercut the plant to form a cone, removing the soil an inch or so at a time, moving all around the plant, until you begin to see that you are removing roots. If possible, then get a square of burlap under the plant. Tilt the plant to one side, put one edge of the burlap close to the center of the plant, wadded up so that only half of it is on the open side of the plant, then rock the plant the other way and pull the burlap through. Tie the corners of the burlap to each other across the plant. Tie the burlap tightly to keep the soil around the plant roots undisturbed. Then lift the plant by the burlap and the bottom, not by its stems. If the plant is very large it is important to dig a wide root ball. Don't worry about digging deep into the soil since most azalea & rhododendron roots are near the surface. Dig the plant, preserving a root ball as wide as can be safely moved. You can lift it onto a tarp and then use the tarp to drag the plant to its new location rather than picking it up. Be sure not to plant too deeply and water it thoroughly after transplanting. Since you will be keeping it out of the ground, I would be best to ball and burlap it to hold the roots in and temporarily mound dirt around it so the roots don't dry out, but also they won't get too wet. If you put it in a temporary hole, that hole could fill with water and drown the roots. It is best to leave the plant in the temporary location about 3" out of the ground but mound soil to slightly below the original depth where it was planted, never higher. Then mulch it with oak leaves, straw, bark chips or whatever, but not walnut leaves. Don't water too often, but never let it dry out either. * Finally, pruning the top helps match the demands of the top to the capability of the roots after they are stressed by the move. People have been known to cut the top off wild rhododendrons before moving and the plants have come back with superior shape. This is drastic and not recommended for a plant you don't want to risk loosing. Rhododendrons and azaleas have dormant buds beneath the bark which sprout to form new growth after severe pruning, hence severe pruning which removes 1/3 to 1/2 of leaf area is quite common when transplanting. Make sure you watch the plant after it was moved like you would a new plant. Its roots are compromised and it will need a reliable source of moisture. If the weather has a dry spell, make sure you water any newly planted rhododendrons, large or small.

Ms Joy, I was all ready to suggest somnething about your dahlia....then realized you are in California and not subject to a killing frost which is the noraml ---usual...northern practice which dahlias are given. So you'd better wait until one of your neighbors suggests something.

i am of the opinion that hosta come up on stored energy .... if you interfere with such too much.. yes... you may set them back ... if you are simply talking about halving a large clump ... probably little or no set back ... if you are talking cutting it into 100 pieces.. then they will probably be stunted ... i tend toward late summer.. when they are already looking ratty .. others here seem to like spring ... 6 of this.. half dozen of the other ... but ...hosta never really need to be divided... which leads me to think you have a plant that is too big in a space that is too small ... why not just get rid of half of them.. and buy some smaller plants... that you dont have to dig up repeatedly??? upgrade one might say ... i dont understand why you want to divide a plant that is already too aggressive ????? so you have twice as many to divide next time????? but as always.. whatever rocks your boat is fine with me .... good luck ken PS: if you a few extra .. try growing them on the driveway ....

My experience - which may not be what other iris growers have learned - is that the very mildest of frosts does not stop the settling-in process. When I planted a large quantity of iris very late one year, I had one unnamed variety that I used as a sort of control. I planted eight of them and dug one up every week to inspect it. This is what I observed. At one week, the dried out roots had started to swell up a bit, a nearly negligible amount. At two weeks, there were the tiniest new roots beginning to bud on the bottom of the rhizome. Average temps during this time were still in the high 50's to low 60's at night. I kept the soil lightly moist during this time. By the fourth week I had some substantial new root growth and the rhizomes felt 'anchored' when I tugged on the leaves gently. It was not until the sixth week, by which point the temps were occasionaly in the light frost range at night, that I saw any new leaf growth. The iris that bloomed the following year were generally those that had some new leaf growth in the fall - the others were fine, but just didn't bloom the first year. When I plant earlier in the season, the root growth seems to happen a little bit faster, and then there's more time for the foliage to grow after the roots become somewhat established. Understand that this wasn't a highly scientific experiment, just some observation over a few weeks in one particular year of late planting. Hope this helps though. katie