Maybe they have phytophthora root rot. Does the soil around them seem wet at all? Any muckiness or bad smells? What about the original soil balls, were they field grown, so that they have claylike soil balls or were they grown in soilless potting media? If claylike rootballs are allowed to dry out between the grower's field and the final purchase and planting by the end consumer they may repel water later, without the purchaser knowing it. Coarse soilless potting media may also remain dry if the soil around it is less coarse.

The soil is not wet and seems to drain properly after a rain. The shrubs were not field grown as far as I can tell and from what I remember looked like they were grown in the 2 gallon containers. I'm not sure if it was a soiless media or something simmilar in the plastic pots. It was the typical dark brown\black "soil". Thanks for responding.

I'll defer to any advice bboy offers, but it sounds like you are on the right track already, areno. I'd dig a few up and tease the roots out of the pot shape. You may consider rinsing off the potting medium, or if there are water absorption problems, using a small bit of detergent mixed in water to get moisture to the roots.

A few more thoughts to consider, in addition to the possiblities of disease, encircling roots, and insufficient water. How much sun do your shrubs receive? (If in full shade, these types of shrubs, especially the "dwarf" rhodies, might not be receiving enough sunlight to put on significant growth above ground or underground even over a 4-year period.) How does the foliage look on your shrubs? Are leaves yellowing or browning, or becoming less numerous? This could also tell you something about the ability of the roots to take up important mineral nutrients from the soil that are needed for growth and maintenance of the shrubs. (Your rhodies will be better able to take up these nutrients in a more acidic soil, and the boxwoods, in a neutral or more alkaline soil.) After the initial tilling and preparation of the soil, has your soil since retained that less-dense structure (as opposed to becoming more compacted)? If the soil around the root balls has become considerably more compacted than what was in the original pots, the shrubs (especially the rhodies) might have been having a difficult time rooting out into the soil and getting nutrients, including oxygen. (Perhaps the organic material you initially added to the soil has decomposed so much that your soil has reverted to a much denser structure?) How's the mulch situation been over the years? And has there been any serious competition for nutrients from a groundcover, like vinca, ivy, or pachysandra?

From your description, I am quite sure that the plants were root bound in the pots. People are often told not to disturb the roots of plants, but, in fact, it is absolutely necessary to disturb the roots of plants that are root bound. One way to do this is to tease out the roots by hand. Another quicker way is to make three cuts vertically around the root ball, cutting into the roots. When you plant, pull the root ball open and make sure soil gets into the cuts.

You should be able to do this now, and the difference this season will be astonishing.

Plants in decent condition before planting will soon make new roots that grow out of the original configuration and into the new soil, even if rootbound. I have seen multiple instances of this myself. Opening up the rootball serves to get rid of the material on the roots (field soil or potting medium), which if markedly different in texture from the existing soil on the new site may cause moisture problems, and to enable deformed (circling, j-rooted, kinked) mature roots from strangling the plant years down the road.

If you cannot discern any new top growth (there must have been at least a little or they would be dead) then there is a severe condition present that is stunting your plants. How good did they look when you bought them? Plants in poor shape before planting are much slower to establish than healthy stock.

Here is a link that might be useful: Successful Plant Establishment

Thanks for all of the suggestions. The shrubs were in great condition when planted and are located in an area that receives 70% full sun. The surrounding soil still looks good and is not compacted. We mulch this area every year. After reading your thoughts I'm thinking that I need to dig up the shrubs and attempt to expand the root base by removing some of the original soil that was in the pots and then teasing\cutting the root structure. I'll give it a try this weekend and hopefully they will begin to grow this spring. Thanks for your help.

I agree with laceyvail. I would dig them up, get a utility knife and make some slashes from top to bottom. You can also pull roots out of the bottom. I've had the same thing happen to me. The roots grow in a circle and never find their way out.

Whenever I plant I really hack at the roots. You will have to dig them up and hack away.

Plants with any kind of vigor do not "never find their way out". Roots of shrubs have two sections: the mature (inner) part near the stems and the immature (outer) part, near the ends and including the root tips where roots elongate. Unstraightened mature root sections formed before planting will stay in the same orientation as when in the pot, but new roots made after planting immediately grow away from the center of the plant. A plant dug up later that has no root growth coming out of the sides at all has not had any obvious root growth at all. For this to happen the interval between planting and digging up later either has to have been winter, when roots may not be very active or the plant is in such poor condition that it hasn't be able to manage much root growth.