Part VIII - Living Walls - Rhododendrons & Azaleas
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- MaryS_10
- Cottage_Garden
- Marge_Talt
- Gay_Klok
- Gay_Klok
- Gay_Klok
- Gay_Klok
- Gay_Klok
- blazeburns
- Marge_Talt
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» MaryS_10 - Mary Stamper Hi Marge... The fact that we've had 14 days s
Mary StamperHi Marge...
The fact that we've had 14 days straight of rain lent some credence to what you said. I had to wait a couple of days until after the rain stopped. Of course then the temp shot up to 90 degrees.
Then I noticed some powdery mildew forming on the leaves and stems of the new growth were drooping.
I decided to exhume the thing. I had planted about 1-2inches above grade. I found that the soil around the root ball was nice and moist. The burlap, which they told me to roll back but leave on was nice and moist, but the root ball was clearly too dry. I know there are near religious arguments about whether to leave the burlap on or off. I followed my instincts and took off the burlap, and followed your advice and set it about 4 inches above grade. Then I watered the root ball well. In about two hours, the drooping stopped. I sprayed some sulphur spray to hopefully get the mildew to cease. The yellowing may or may not be related to a dry root ball. With all of the rain we had, it could very well be that I had BOTH problems. I'm wondering if there would have been an advantage to planting balled and burlapped plants in the fall instead of spring so as not to have to contend with excess heat while the root ball is so small. Is it my imagination that balled and burlapped plants take more babying than container grown ones? It would make sense because of the dramatically reduced root surface. By the way, I found very little root growth sticking out of the ball when I removed the burlap. I'm still not certain how to tell when it needs watering...I hate to wait until leaves start to droop because that seems to me to indicate that stress is already taking place. Any tips on how to tell if water is needed? Sometimes soil FEELS cool, and it's damp enought that I wouldn't want to sleep on it myself, yet the plant droops after the hottest part of the day. I'm still a bit confused about this watering stuff.
-- posted by MaryS_10
» Cottage_Garden - Sometimes the original soil that the ball and burlap plants are
Sometimes the original soil that the ball and burlap plants are grown in is radically different from the soil where we plant it and the two do not mesh well.Sometimes the machines used to dig the ball and burlap plants compress and compact the soil around the root ball so tight it causes a problem later. (This can also mound soil up around the root flare resulting in planting too deep.)
Sometimes ball and burlap plants come with a muddy casing of clay-based soil around their roots which is probably supposed to help retain moisture around the roots but can end up inhibiting take-up of moisture if it is allowed to dry out at any stage of the process. That clay "shell" can also be extremely difficult to rehydrate, even if the soil on both sides (meaning in the ball and surrounding) is not.
For all of these reasons I actually almost prefer bare-root plants! At least I am dealing with a known factor (my soil) and can take steps to accommodate the rooting and adjustment process accordingly.
Just as an aside, there are many types of synthetic burlap being used now and they do not degrade the way the natural fiber will. (Sometimes I think there are so many traps for the gardener and it is amazing anything ever grows!)
Barbara Martin
The Cottage Garden Editor
-- posted by Cottage_Garden
» Marge_Talt - Well, Mary, everything Barbara says is true - especially the par
Well, Mary, everything Barbara says is true - especially the part about traps for the gardener. Unfortunately, in today's world, the advice given by many nursery personnel is erroneous or incomplete. Around here, at least, you seldom find anyone at a nursery during the high season who really is a gardener, much less a knowledgeable plant person.I think they tell everyone not to take the burlap off because they assume most people don't know enough to try to keep the rootball intact or what to do if it isn't....so they opt for the lesser of evils.
I'm one for removing the burlap if at all possible and if the rootball is too big to manhandle and get it out from under, I cut it off as far down as I can.
I want to see the rootball so I can make some semi-intelligent judgement about what condition it's in. If it's one of those mashed into a clay mass or covered in clay, I make a point of disturbing it as much as I can without really wracking the root system - just so the roots can get out of it and into the surrounding soil.
I've found that many rhodies are grown in nurseries in very sandy soil - at least a lot of them I've gotten B&B. This does make life interesting since, as you've found, the rootball will be dry as a bone while the surrounding soil is moist. If this is the case with yours, you may want to run the hose slowly right at the base of the trunk, weekly, even if there is some rain - just to make sure that rootball remains moist. Sometimes rain just doesn't penetrate through the leaves right at the trunk area and it remains too dry.
I don't think it's your imagination - B&B plants do need more care than container grown ones. Lord only knows how many roots were cut off when it was balled. And, since rhodies have a shallow, spreading root system, they can remove a lot of them when making a "compact" rootball!
Other than monitoring drooping, the only way I know to figure water needs is to ram my fingers into the rootball to make sure it's damp. If it is damp, then watering isn't needed. If it's really hot and the new growth is drooping, you might do some misting around the foliage even if the root area is moist. Rhodies like a good deal of humidity.
It is better to figure out what state the soil is in before drooping occurs because that does indicate stress is happening.
Is this guy in the sun? If so, you may want to rig a burlap screen to give it some shade during mid day and afternoon while it recovers and grows roots. If it is trying to flower, you may want to foregoe the flowers so it can put its energy into making roots. If it has already flowered, dead head it so it won't try to set seed.
If the new growth continues to droop really readily, remove it so the plant doesn't have to keep trying to keep it hydrated. Once the plant recovers, it may try to put out some more growth this year and if not, then it will next year. The important thing is to reduce calls on the plants reserves while it is trying to recover from root pruning.
I've read glowing accounts of Superthrive - never used it myself, but those who swear by it say it is marvelous, especially for newly planted stuff or stressed plants. You may want to try that or one of the liquid fertilizers designed for promoting root growth - Roots for Acid Lovers comes to mind; or liquid seaweed. Can't say for sure these will make a difference, but my philosophy is that they couldn't hurt.
Since you've obviously found the cause of the drooping as well as the mildew (dryness) you're well on the way to solving this. Now, I'd just keep an eye on the plant and make sure it has moist soil and wait for it to recover. These are a tough breed of rhodie and it should do alright for you.
Keep me posted on its progress, OK?
Marge
Gardening in
Shade
-- posted by Marge_Talt
» Gay_Klok - There are many gardeners now preaching the removal of everything
There are many gardeners now preaching the removal of everything before planting -When a plant has been in a pot for a longish time, the roots learn how to confine themselves into that area of constriction. This is very detremental to such surface rooting plants such as the Rhodos and Camellias.
The consequence of this is the roots begin to grow in a circle. When placed with the root ball into your well prepared growing area, the roots continue to curl around themselves and end up strangling themselves. The new theory is that on receiving a plant that has been confined for a growing season, whether it be in a pot or burlap, the planter should brush most of the soil away, uncurl the roots and if necessary, cut them so you can sort of comb them out. It is obvious if the roots have been growing in good soil and have not been confined, then it is preferable to plant undisturbed.
Two more observations - quite often plants such as Rhodos don't show lack of water or too much water until 1 ir 2 years later. The other is that it is a good idea to build up the area where the plant is to be placed
Tasmanian Garden Journal Come for a stroll in my garden, great photos
-- posted by Gay_Klok
» Gay_Klok - There are many gardeners now preaching the removal of everything
There are many gardeners now preaching the removal of everything before planting -When a plant has been in a pot for a longish time, the roots learn how to confine themselves into that area of constriction. This is very detremental to such surface rooting plants such as the Rhodos and Camellias.
The consequence of this is the roots begin to grow in a circle. When placed with the root ball into your well prepared growing area, the roots continue to curl around themselves and end up strangling themselves. The new theory is that on receiving a plant that has been confined for a growing season, whether it be in a pot or burlap, the planter should brush most of the soil away, uncurl the roots and if necessary, cut them so you can sort of comb them out. It is obvious if the roots have been growing in good soil and have not been confined, then it is preferable to plant undisturbed.
Two more observations - quite often plants such as Rhodos don't show lack of water or too much water until 1 ir 2 years later. The other is that it is a good idea to build up the area where the plant is to be placed
Tasmanian Garden Journal Come for a stroll in my garden, great photos
-- posted by Gay_Klok
» Gay_Klok - There are many gardeners now preaching the removal of everything
There are many gardeners now preaching the removal of everything before planting -When a plant has been in a pot for a longish time, the roots learn how to confine themselves into that area of constriction. This is very detremental to such surface rooting plants such as the Rhodos and Camellias.
The consequence of this is the roots begin to grow in a circle. When placed with the root ball into your well prepared growing area, the roots continue to curl around themselves and end up strangling themselves. The new theory is that on receiving a plant that has been confined for a growing season, whether it be in a pot or burlap, the planter should brush most of the soil away, uncurl the roots and if necessary, cut them so you can sort of comb them out. It is obvious if the roots have been growing in good soil and have not been confined, then it is preferable to plant undisturbed.
Two more observations - quite often plants such as Rhodos don't show lack of water or too much water until 1 ir 2 years later. The other is that it is a good idea to build up the area where the plant is to be placed
Tasmanian Garden Journal Come for a stroll in my garden, great photos
-- posted by Gay_Klok
» Gay_Klok - There are many gardeners now preaching the removal of everything
There are many gardeners now preaching the removal of everything before planting -When a plant has been in a pot for a longish time, the roots learn how to confine themselves into that area of constriction. This is very detremental to such surface rooting plants such as the Rhodos and Camellias.
The consequence of this is the roots begin to grow in a circle. When placed with the root ball into your well prepared growing area, the roots continue to curl around themselves and end up strangling themselves. The new theory is that on receiving a plant that has been confined for a growing season, whether it be in a pot or burlap, the planter should brush most of the soil away, uncurl the roots and if necessary, cut them so you can sort of comb them out. It is obvious if the roots have been growing in good soil and have not been confined, then it is preferable to plant undisturbed.
Two more observations - quite often plants such as Rhodos don't show lack of water or too much water until 1 ir 2 years later. The other is that it is a good idea to build up the area where the plant is to be placed
I'm sorry if this appears twice, it won't seem to post it.
Tasmanian Garden Journal Come for a stroll in my garden, great photos
-- posted by Gay_Klok
» Gay_Klok - Marge, I'm really sorry. I am having trouble posting. I only c
Marge, I'm really sorry. I am having trouble posting. I only clicked once and went to answer the door bell, so it was not impatience! I did click again after I got back. I hope you know how to remove multiplesTasmanian Garden Journal Come for a stroll in my garden, great photos
-- posted by Gay_Klok
» blazeburns - A couple of Rhododendron questions
I've had a difficult time maintaining healthy Rhododendrons since I've moved to northern Virginia. I think the cheif cause is awful, nearly all clay soil, in conjunction with difficult weather conditions the last three years (two droughts and a very rainy year this year). Many of the remaining plants are exceptionally large and I don't think it is feasible to remove them to raise them or relocate them to a prepared area. Are there any steps I can take to amend the soil?Also, I lost one of the very large plants this year (I think due to root rot) and received advise from the garden center that I should remove the dead plant's roots or the fungus in the ground would spread and also taint the earth so that no Rhodie or Azalea could ever be planted there again. I made an effort to remove the dead roots, but it appears the task may be extremely difficult due to the size of the roots and proximity to other healthy plants. Is it absolutely essential to do this? I will do it if it is, but it sure would be nice if I could avoid it.
Thanks in advance for any help you can give.
-- posted by blazeburns
» Marge_Talt - Re: A couple of Rhododendron questions
In response to message posted by blazeburns:Welcome to Gardening in Shade!
Clay soil is more a problem than the weather, tho' the last few dry years have not been kind to rhodies.
However, if your plants have survived being planted in clay long enough to become too large to comfortably move, then IMO, they have adapted to it pretty well.
The best thing you can do is keep them mulched with pine bark or pine needles or both and make sure the soil doesn't dry out for them. Their root systems are fairly shallow and very fibrous - as you've probaly found out trying to dig out the dead ones. They will not appreciate a lot of digging and scratching around within the root spread.
If you think that your soil isn't draining when it rains a lot (and losing that one to root rot indicates this may be the case), you can also dig some drainage trenches between the plants.
If the ground is flat, you'll need to dig the trench so the bottom angles down to a hole filled with gravel (a french drain). If they are on a slope, you can trench out to daylight.
The trenches should be as deep as the bottom of the plant root balls so that water will drain away from the roots and into the trench and be carried away.
Fill the trenches with small gravel and sand and cover with mulch. This is a fair amount of work, but less work than trying to lift and move a very large plant.
Root rot and wilt in rhodies (and other ericaceous plants) is caused primarily by the fungus Phytophthora cinnamomi, but other Phytophthora species can be involved. It's a disease often rampant in propagation beds.
Flooding, water shortage or salinity stress can compromise resistance to these pathogens,according to my handy dandy Diseases of Trees and Shrubs.
These diseases are most severe in imperfectly drained soils because water-saturated soil promotes formation and dispersal of sporangia and zoospores.
This is probably why you lost the plant this year...it was stressed in previous drought years and all the rain we had this year waterlogged the soil.
The fungi do survive in soils in dead plant debris, not the actual soil, so the advice to remove infected roots is good because they create an incubator for the pathogen. I would get out as many as you can and dispose of them in the trash. Try not to injure the roots of healthy plants in doing this.
Also, clean up any dead leaves or twigs from the ground under your rhodies - even the healthy ones - since water splashing up from dead material on the ground is one way these fungi are spread.
The book does not give any 'cures', but it does say that it can be avoided in nurseries by growing plants in root substrates that are supressive to the pathogen, e.g. composted hardwood bark or substrates at pH near 3.5...very acid.
Considering this, making the soil as acid as you can might help. I'd be inclined to try to get out as many of the dead roots as possible and then pack the hole with peatmoss ( which is about the most acid substance you can readily get) and mulch with a load of pine bark fines and then some composted hardwood bark.
If you could get your hands on long fiber sphagnum peat, would probably be even better than the peatmoss sold in bales, as it is noted for having anti-fungal properties.
You also want to sterilize any tools you use in working with dead material - keep a bucket of chlorox water handy to dip them in (1 part chlorox to 9 or 10 parts water) - and for sure before you use the same tools on a healthy plant. This also goes for pruning tools used to remove dead stems from otherwise healthy plants.
Rhodies are subject to a number of die back pathogens. I've lost some and bits of others, but if conditions can be made to suit them (i.e. sharp drainage, acid soil and consistant moisture) most will survive attacks. It's when they get stressed by something else that they succumb to one of these nasties.
Best of luck!
-- posted by Marge_Talt
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