I've known for a long time that the potting medium used by Trader Joe's and other grocery stores has to be shaken off the plants before they go into the ground. Grocery stores use various types of moisture-retentive media to keep the plants looking saleworthy even after a long time on the store shelf. In the garden, however, this medium tends to rot the plants.

Now I've discovered another type of potting medium that's harmful to my plants. The medium consisting mainly of tree bark apparently does not work well in my garden.

I have no trouble growing bare-root roses, and when own-root band roses are planted in my garden, they're planted with considerable amounts of potting soil and my own garden soil, so any harmful effects of the medium the nursery used are counteracted.

In some cases, however, nurseries sell own-root roses in larger containers filled with tree bark, and these are the ones that are beginning to fail in my garden.

I've started digging up the roses that haven't grown much since they were planted or, worse yet, have shrunk in size since they were planted. What I find around the trunk is a mass of something resembling dry sawdust, which never seems to mix with the soil around it. In most cases, these are roses from Roses Unlimited, although some are grafted roses I bought in 5-gallon containers from Garden Valley Ranch, which also uses a bark-based medium.

I'm wondering whether the nurseries sometimes mix bark with allelopathic properties (cedar, spruce, etc.) into their medium. This would stunt the growth of the roses and eventually kill them. Even more troubling is the tendency of this bark to decompose into matter that retains no water and is unaffected for the better by the surrounding garden soil, which is sandy loam in my garden and couldn't be any better.

During a Master Gardener class, I watched a speaker demonstrate how water moves poorly from one type of soil to another - regardless of what sorts of soil he used. I have always believed that plants do best if their roots are in contact with the garden soil in which they are to grow with no intervening amendments. I am quite sure most of us do not have bark for soil in our gardens, so I would think it would always be advisable to eliminate as much of the potting medium in which the rose was originally growing possible - without sacrificing roots - before putting it in the ground.

Are you thinking too much of the bark based media was incorporated with your garden soil, or that just having been grown in that media weakened the plants? I've definitely seen issues with both peat and bark based mediums, and make efforts to hose off most of it upon planting, but I just hose it off into the planting hole and mix it with the garden soil, and the problem seems to be taken care of.

I haven't reached a final conclusion yet, and that's why I'm interested in other people's theories, but I now tend to think that the bark-based medium does not incorporate well into my garden soil when it's added in quantities larger than a band or quart, probably because of the phenomenon Porkpal mentions -- the inability of water to move efficiently from some types of media to others..

I'm not sure that the plants were weakened merely by being grown in that medium, unless it sometimes included allelopathic barks. I'm now wondering whether that's the reason that rooted cuttings from Vintage Gardens and Rogue Valley, for instance, were always less likely to thrive than rooted cuttings from some other own-root nurseries. The bark-based mulch available from our local landscaping companies should only be used in pathways because it often contains bark from eucalyptus, fir, and sycamore trees. Those trees are quite common here, and their bark does harm plants. Maybe the potting medium used by Vintage Gardens, which was our local own-root nursery, contained those types of bark.

I guess my tentative conclusion is that roses grown in containers with a bark-based medium should stay in containers. If they are to be planted in the ground, the bulk of the medium should be removed from the plant before planting, as you suggest, Neal. That's my tentative conclusion after seeing what happened to some of my failing roses, but I'm still just theorizing.

This is a most interesting thread, for sure.

I went to a rose growing "lecture" once (for lack of a better word...it was a two hour, one day gig) which was geared to growing roses in my area and in the type of soil common to this part of the state.
The person giving the talk said to never use ammendments with redwood in them for roses...something about the tanins in it that roses don't like when it's incorporated into the sandy clay soil we have here. Prior to learning that I had used redwood conditioner, but then stopped using it, switching instead to compost. It did make a big difference in my roses...that plus the fact that redwood soil ammendment is scare anymore.

Here's what I don't get: "Potting Soil" is usually predominantly made up of assorted "barks" as the main ingredient anyway,(along with peat and some sand, perlite, etc.) and technically isn't "soil" per se. Lighter weight for use in containers (pots) and will get depleted of any nutritional value after a while, once the plant uses what's available and then that which is flushed out from watering the container. These potting "soils" seem to become inert after X amount of time. It seems to me that compost would be a better (and cheaper) soil additive.

If you have a rose growing in a band with potting soil and then transplant it into the ground, how can that small amount of soil from the band affect the ground soil that much ? The root system will (hopefully) take off and extend well beyond that small amount of potting soil into the surrounding "native" soil. IN TIME that original potting soil will just decompose and be replaced by roots.

Years later when you dig up a plant from the ground that was once planted in nursery potting soil, that original bit of potting soil it originally came in is pretty much broken down and decomposed and the plants roots have taken over that space. Granted, some of does remain but how can it be that much of a problem ?

I guess my main question is why would you want to add potting soil to the ground soil vs. compost ?

Otto and Sons (rose growers in Filmore, Ca.) has a very unique soil mix that they use. I've tried to decipher what it's made out of, but never could.
It's a very heavy potting medium...way heavier than any medium I've ever seen from any grower, yet their container roses thrive in it. The first time I went there and actually went to pick up a rose in a 5g container I was in shock at how heavy it was, yet the plant was thick and massive and about 4' tall. Their roses are also able to live in those containers for much longer than roses I've bought from other nurseries that are planted in very lightweight mediums and look like #%$@ after about 6 months. I tried to find out what they're mix is made of and they wouldn't reveal that. Can't blame them I guess.

Also, remember that a lot of growers feed their roses a diluted solution of fetilizer every time they water vs. one heavier feeding every month of 6 weeks, etc.

I've never fully understood why some people hose off all the soil from the roots of container nursery stock before they do in-ground planting. In doing so, all those millions of root hairs get broken off or destroyed and those are the first parts of the root system that take up water. It seems to me that when you do that you're setting the plant back by 6 or more months and doing more harm than good, not to mention wilting of the new top growth. Isn't it better to just break up that original root ball by X % instead of washing off all that original soil ? Just curious.

To answer your main question (Why would you want to add potting soil to the ground soil vs. compost?), I should first explain that the potting soil I use is more properly called "planting mix." Years ago, Annie from Annie's Annuals said that she always uses planting mix rather than potting soil. I've followed her advice ever since. It's much cheaper than potting soil and it works better in the ground. As for using compost instead, I've had good results using compost as top dressing, but not as a planting medium.

The reason that I have to use something in addition to garden soil when I plant a band rose or any other plant is the Arum that plagues my garden. I think I've told you that this horrible stuff has spread to every part of my garden, driving me nuts by obscuring the shorter plants from October to March or April, when it mercifully dies down for the year. When I dig a hole to plant something, I take the opportunity to remove all of the Arum bulbs from the soil I've removed. Once they're gone, there isn't enough garden soil left to refill the hole unless I mix it with something else.

Here's a photo of the mess the Arum makes of my garden. There's an azalea hidden by it in the top left corner. You can only see one of the blooms. And a new little camellia is trying to push a bud above the Arum in the bottom center.



When I see this stuff for sale on websites, I can't believe anyone would pay for it. Mine came from a houseplant one of my neighbors mistakenly planted outside. Every house in the neighborhood is now overrun by it.

We cross-posted here, but I agree and disagree with your new comment. It's true that carelessly hosing off the nursery medium could break the feeder roots, but I shake it off in the case of the Trader Joe's medium for mini-roses, and I'll probably soak it off any new potted roses I plant if the nursery has used a bark-based medium. I don't wash the soil off if there's any soil, but some nursery media don't seem to contain any soil. In any case, there's no need to use a strong hose spray to remove anything.

I can't say anything about your fertilizing comment. I've never used fertilizer on anything in my garden, aside from Osmocote pellets in pots of annuals. Daily watering is almost essential here in summer and I can't imagine fertilizing every time I water. For one thing, I'd soon go broke.

I started hosing the media away from the roots of potted nursery plants a few years ago after losing a couple of plants. Upon pulling them out, I could see the roots hadn't grown beyond the original container space. My soil is heavy, and I felt like the roots had trouble growing past the soft, airy potting medium. I gently hose the media away from the roots, while filling the planting hole with water, and have never had any wilt or damage as a result. Actually, they seem to take off faster. I find it particularly important when planting in summer or fall, to encourage rooting into the native soil and help with winter survival. I had the theory that the failed plants I mentioned above died from winter kill, because of the airy potting media allowing so much cold air around the roots.

http://www.sfgate.com/homeandg...

"Gently" hosing is probably a good idea, Neal, and the proof is that it works for you.

Good link, Margie, but a bit confusing. It says I should add "substances like aged manure, alfalfa meal, fish meal, earthworm castings or guano" to my planting mix, but all of these are already listed as components of the mix I use. At any rate, I've never had trouble growing plants this way. I only have trouble with the plants I remove from containers with a bark-based medium and plant into the ground without removing the bark.

That sounds like another "works for you" commendation.

It really is wonderful how we find, through trial and error, what works for us, isn't it, Porkpal? If we didn't, we wouldn't be on this site because we would have given up on gardening long ago. I'm always amused by books and articles that try to proclaim universal rules and methods. We can only tell people what works or doesn't work in our own gardens.

Zuzu said:
"Good link, Margie, but a bit confusing. It says I should add "substances like aged manure, alfalfa meal, fish meal, earthworm castings or guano" to my planting mix, but all of these are already listed as components of the mix I use."

You are right Zuzu it is a bit confusing but I think you clarified it.
Here's my question: what type of soil do I use for propagating rose cutting and transplanting into a container? On Oct. 21, I followed the directions from a website: "Hartwood Roses: How to Root roses From Cuttings". I made up my own soil mixture composed of top soil, Dr. Earth's potting soil, vermiculite, perlite and Bumper's Crop organic soil amendment (everything but the kitchen sink - lol). The cutting is showing new growth now. If it doesn't bite the dust when and what size container do I place the cutting in. And what type of soil mixture do I use.? Because it's winter here in NY, I have it in the basement till Spring. Thanks - Margie

Congratulations! That's very exciting that your baby cutting is showing new growth. Your soil mixture sounds exciting too! If you're going to continue growing the plant in a container, I think you should stick with that same mixture, although I personally would leave out the vermiculite after the rooting stage. It retains moisture better than perlite does, and it's therefore a good ingredient when you're trying to root a cutting, but some of the existing vermiculite available to us has been contaminated with asbestos. In any case, it isn't that useful in a potting mix after your cutting has developed good roots.

I usually start cuttings in a 1-gallon container and gradually move the successful ones into 2-gallon, 3-gallon, and 5-gallon containers. After that, they usually go into the ground, mainly because I've discovered that I'm now too old to lift larger containers once they're full of soil and plants.

One of my favorite nurseries here in town used to sell 5 gallon roses in pots so heavy I couldn't get them out of the trunk. They potted the roses in clay soil from their property and nothing else. Those roses grew nicely. Every time I bought a rose from them, I cursed them, because I had to cut the pot off the root ball. There was no breaking up the root ball, it just had to go in the ground the way it was. I think those roses grew even better once in the ground because they were so happy to find my loamy soil. I was sorry to see that nursery close, but I was happy to buy every rose she had left on closing at a very very low price.
The bark-based potting mixes do not work for me at all. The bark in our bags is most likely pine from Texas or Georgia.
Our master gardener classes teach people to plant in regular garden soil without any amendments. I prefer to break those rules and mix compost in with the soil when planting roses. (Not with trees, though) I top dress with compost, too. Sometimes it's my own compost from my tumbler, other times it's a bag of cotton boll compost or mushroom. Horse manure shredded with alfalfa and aged 3 years is the best in my opinion. A guy near me sells it by the dump truck load but it isn't cheap. My husband bought me a truck load for my birthday one year--best gift ever!

I've found that roses that come from big boxes have either a very gritty soil mix (Lowes) or a barky mix (Home Depot). The gritty soil mix just falls off the plants naturally when I pull them out of the pot, but they seem to do better than the ones that come in the barky mix. Roses grown locally by the nursery are hit & miss. I have stopped buying roses from one nursery because almost 100% of them never make it in my soil. The nursery closest to me is a 75-25% shot because they're greenhouse grown & that means I have to harden them off for almost 2 weeks (dragging them in & out of the garage daily, which is a pain in the patookie 'cuz I'm lazy) as my spring is just way too erratic to direct-plant. The roses that seem to do the best are the ones that come from Weeks directly (they have big Weeks pots). I usually just pull them out of the pot & plop 'em in the ground w/o removing the potting soil that they're in. But one huge disadvantage that a local grower does here is feed everything through troughs that the plants sit in, so there's usually a HUGE mess of roots coming out of the bottom of the pots. Impossible to get the plant out of the pot w/o destroying all these roots, plus I don't feed every single week like the grower does, so they usually aren't happy with me (the plants, dunno about the grower) and pout for a while. But, with my super short growing season, I tell the plants to suck it up or die!

When I plant anything that is coming out the bottom of the pot, I just destroy the pot in order to save the roots.

I do that too. I use metal shears to cut through nursery pots.

Here's 2 photos of my baby cutting. And one photo of it's mother (red corsair) - Margie