Rescuing a Rhodo from underground attack
Posted by: sydh at 23:50, May 26 2013.
Kay's 'Red Ace' has a root-mass infested with Euphorbia. Replanting the rhododendron gives you the opportunity to try it somewhere safe. Decide on a suitable site for rehabilitation: fair shelter, brisk drainage and pH below 6.8. Lever the root-mass of the victim with a fork to get an idea how wide and deep a hole it will need. At the new site, mix a generous proportion of composted bark or equivalent material such as leaf-mould into an area twice that of the branch spread and a spade deep. Settle it down with a knifing action of the spade. Excavate a suitable hole in the middle of the prepared site, and sieve the soil excavated using the finest mesh you can find. Mix the fine soil with equal volumes of damp peat and gritty sand that is free of all saltiness and shell fragments, but add no nutrients.
On a calm day dig out the victim and wash all the soil out of the root-mass, then pick out every fragment of the attacker. Note whether any honey-fungus bootlaces are attached to roots: if so then cut out each affected root at a point as near to the crown as you think the plant can spare.
Shake the cleaned plant dry and set it in the prepared hole using the sievings to raise the plant if needed to get its collar a cm above ground level, and use more sievings to keep the plant upright. Now work the fine mixture into the root mass working up from the bottom. If there is not enough mixture use peat&sand mixture until the whole mass is filled. Pack sievings into the space around the root-mass and sprinkle water through the plant until the root-mass is puddled and the topmost roots are visible. You'll never drown the root-mass this way but you will avoid a drought inside it.
Next morning make good with fine mixture or peat&sand where the first filling has washed down, until the root-mass is covered up to collar level. Be careful not to bear down on the root-mass at all. Then gently lay a non-compactable mulch beneath the branches and erect a wide cylindrical wind and sun screen made from a big plastic bag (from a peat bale perhaps) cut along the long sides and held clear of the shrub by a palisade of at least half a dozen of my free 4-ft canes. Sprays of water over all the foliage will be appreciated in the evenings whenever summer weather finally appears.
If Red Ace notices any of this, it will be grateful, not hurt. I wouldn't want to give it any nourishment until it's been in the new site for a month, but then I'd give enough very dilute Ericaceous Miracle-gro as weekly foliar feed - enough to penetrate the mulch. No more feeding (as for any outdoor rhododendron) after mid-August, firm with the sole in early autumn only if the plant seems a little loose, and leave the screen in place until next Spring.
