Producing good strong roots.

[martenfisher]

Most all my cactus plants look healthy. Except for the roots. I am taking notice that pretty well all of them are wobbly and loose in the ground. I pulled up a weed by one and the whole cactus came up with not much for roots. My cactus plants in pots are doing the same and some have no roots at all.
Do I need some sort of special fertilizer? Do I need to ammend the soil with a certain substance? I know some will reffer me to soil page of this site but that does not address my issue. When I plant a cactus it takes off strong but long term they tend to stop and then not having healthy roots. Constant repotting seems to help with some but I can't repot every cactus every month. I don't water them much and my water does have chlorine.

[iann]

Bad roots, wrong soil. Fix the soil, and possibly don't water so much.

[Saxicola]

Tell us about the growing medium you use. My guess is it is too heavy and is holding too much water, is too compact, or both. You say you don't water them much, but how often do they get rained on?

[martenfisher]

The cactus plants in the ground have organic material and sand since the ground is already sand. The surface is mulched. I never water the ones in the ground ever. I used azomite rock dust on the ones in the ground.
The ones in pots have a course mix with pine bark.
The ones in pots are more dry than wet. We are in a drought and are not getting much rain. I would say the plants did better back when it was raining.

[A. Dean Stock]

At least part of your problem could be the bark you are using. I can no longer find bark produced in the U.S. that will grow orchids and in fact most bark available now is toxic to plants. Aged pine bark from New Zealand works but I doubt that bark mixes are good for most cacti. I know that my initial experiments with Opuntia in bark mixs caused me to completely abandon bark as a component in any Opunita potting mix.
Dean

[martenfisher]

Thanks Dean. Good to see you still around. And the root loss is also in my other plants as well and not just my cacti.

[Saxicola]

So this is happening with non-succulents too? What other sorts of plants? Are they showing any visible signs of trouble or distress? "Normal" plants tend to visibly react to bad situations faster than succulents so they can be useful in diagnosing common problems. Even if the bark isn't the problem now, I tend to agree that it isn't the best additive to a succulent growing medium. Can you clarify if your potted plants have any of your natural soil in as part of their mix? I'm just trying to think of what all of your plants in ground and in pots have in common. What trees do you have in your yard? I know that Eucalyptus can sometimes harm or even kill other plants with the oils in its leaves and roots. Sorry if I'm asking a lot of questions, I'm just trying hard to figure out what could cause this across your collection.

Dean: I wasn't aware of the problems with orchid bark. What do you think they are using that is causing the problem? What would you use instead of bark for orchids (or whatever)?

[Peterthecactusguy]

Bark stays too wet even for water thirsty Opuntia. I have found that native dirt mixed with Diatomacious Earth is the best mix.

[martenfisher]

It is not all my plants in the ground but several. Most all my plants in pots except for tomato. Only thing keeping them going is me dumping old dirt and putting in new. Part of the problem is stress free tops. I know stress free tops and poor roots can be over use of nitrogen but I don't use nitrogen hardly at all. I have very few trees the ones I have are acacia, plums, birch, oak, and redbud.
That is what gets me is how great everything looks but the roots seem to be going away. I almost wonder if insects are doing this and I just am not aware of what ones.

[Dmyerswny]

How often are you repotting these things? It sounds like your constantly repotting. Maybe that's part of the problem.

[Steve Johnson]

It is not all my plants in the ground but several. Most all my plants in pots except for tomato. Only thing keeping them going is me dumping old dirt and putting in new. Part of the problem is stress free tops. I know stress free tops and poor roots can be over use of nitrogen but I don't use nitrogen hardly at all. I have very few trees the ones I have are acacia, plums, birch, oak, and redbud.
That is what gets me is how great everything looks but the roots seem to be going away. I almost wonder if insects are doing this and I just am not aware of what ones.

I'm afraid that whatever basic horticultural knowledge I have is limited to desert cacti, so I can't help you on the other plant life you've got. But with cacti, maybe I could be at least a tiny bit of assistance here...

I can see 4 possible issues to pursue:

1. Potting medium. I steer clear of all mixes that call themselves "cactus" at big box stores and general-purpose nurseries. When I started my new collection coming from a local c&s nursery last June, I did use their cactus mix which actually seemed rather decent at the time -- especially compared to the usual crap I wouldn't even look at elsewhere. However, after 5 months of regular watering followed by a dry fall and winter, I repotted all but a couple of my cacti and it gave me a good look at what the nursery's cactus mix was doing. Essentially, the soil had become compacted over a fairly short period of time. Roots that should've been spreading out simply couldn't get past the barrier of soil compaction, leaving me with root balls scarcely worthy of the name. I've just started using a pumice/decomposed granite mix. Although this has been going on for only a few weeks, I can already detect significant improvements among various cacti in my collection which are rebuilding their root systems. Not enough time yet to get excited about sharing the results, but I'd like to post a more definitive report on the forum in about a month if other members could benefit from my experience.

2. Moisture retention -- goes hand-in-hand with what's in the potting medium. Organic matter should be as little as possible, preferably none. The mix needs to drain freely, but commercial cactus mixes go in the opposite direction. Desert cacti don't like wet feet, so if their roots are in a mix that takes too long to dry out, those roots will suffer sooner or later. I can get easy access to DG and pumice, although I don't know where or if it's available outside of SoCal. A number of people have posted about their own custom cactus mixes on the Cultivation forum. Depends on what materials you can get access to, but it wouldn't hurt to consider some ideas there. With that said, I'd recommend against Perlite. It floats away, and a big pain in the backside for dealing with cactus mixes. If you can't find pumice to get better drainage in your mix, look at Turface, NAPA Oil-Dri, etc.

3. Fertilizer -- completes the cultivation trifecta. My feeling is that it's a common mistake to rely on whatever fertilizer may already be in the mix. If we accept the premise that commercial cactus mixes on their own are just plain wrong, then you'll either be adding a lot of mineral component to the commercial mix or making your own custom mix. At that point regular fertilizing is an absolute requirement, although it gives you a lot more control over nutrient uptake. I did quite a bit of research on the subject to determine what I believe is the best fertilizer for desert cacti. I covered this at http://www.cactiguide.com/forum/viewtop ... 25&t=24810" onclick="window.open(this.href);return false;, so I'd recommend a thorough review of the posts on that thread, and you may find it rather useful. However, I can't claim to have "the" answer, and what I'm saying here is just my opinion for whatever it's worth.

With regards to watering your cacti, Chlorine in your tap water isn't your biggest concern -- it's the issue of Calcium Bicarbonate. If you have an ample supply of rainwater, you're fine unless bark in your soil amendments are creating complications. Once again, I can't speak on plants other than c&s, although it would certainly apply to any cacti you have in the ground. If you have cacti in pots and get rid of the bark, we'll assume that you're now using a properly draining mix with regular fertilizer. This brings us to:

4. Rain vs. tap water. Rain produces neither Chlorine nor Calcium Bicarbonate, so it's the purest water you'll get. Airborne Nitrogen will dissolve in water through precipitation, although I don't know if thunderstorm activity is required. This is way beyond my expertise, so hopefully someone who is an expert on the matter can tell us when/if rainwater needs to be supplemented with a dilute fertilizer. On the other hand, all underground water sources will be hard to one degree or another, and hard water means Calcium Bicarbonate with a tiny percentage of other Bicarbonates. It's the Calcium Bicarbonate (aka Lime) we need to be most concerned about because it builds up in the soil over time, and slowly robs plants of their ability to absorb water and nutrients through the roots. If tap/well water is your primary or only source for watering potted plants, it is therefore essential to neutralize the Lime as much as possible. This can be done through acidifying your water. Diluting 5% vinegar is a good way to go, although other methods are more cost-effective if you're maintaining a lot of plants. Elton Roberts and Malcolm Burleigh presented an excellent article on cactus and alkalinity at their CSSJ website, which I have referred to a number of times before. I highly suggest reading Elton's article in depth before determining the best approach for acidifying your water based on the size of your collection. Here's the link:

https://docs.google.com/file/d/0Bwfo_53 ... l=en&pli=1" onclick="window.open(this.href);return false;

The theory behind acidification is fairly basic in the fact that neutralizing the Lime in hard water should reach a pH of 5.5 - 6.0. While perfect neutralization of all Calcium Bicarbonate is impossible, the idea is to minimize its impact on soil buildup. It's also very important to remember that the fertilizer being used is likely to lower the pH to some extent, so dilution amount of the acidifying agent (vinegar in my case) must be determined after dilution of the fert to reach a final pH no lower than 5.5. The colorimetric indicator kits at hydroponic stores can be highly inaccurate, so I personally wouldn't trust them. Decent pH meters that are inexpensive can be found on Amazon. You don't have to keep checking pH constantly, but if you feel confident in the meter you're using, periodic checks are a good idea just to be on the safe side. As Ian mentioned to me recently, pH meters do take a fair bit of kit to use, although it's not difficult if you follow the meter's instructions.

I realize that I'm giving you way more info than what you were originally asking about. I also realize that people who are just casually interested in growing cacti probably won't go to all the effort I'm describing. That's fine, and it's totally up to the individual. However, I've been piecing together numerous bits and pieces from what I've learned through the forum. My goal is to connect the dots in understanding cultivation, so hopefully I've done a reasonable job to help advance what we're all ultimately about here.

[martenfisher]

Steve thanks alot. You answered many concerns I had. One thing is understanding the PH balance and if cactus like the lime in water or not. I have also never understood how cactus plants like to be fertilized because I did not know the fertilizer sensitivity of cactus. We don't have decomposed granite here but we do have turface. I do use turface and large grit sandblasting silica. But I also have the coco figer and pine bark. When I pot the cactus plants the pot fills with gorgous roots. The plant grows and looks great. Several weeks later or months I notice they just stop in their tracks. Then I look at the roots for health and the dirt falls apart. Then I repot them and the new roots fill the pot and the cycle continues.
I am going to copy and paste your post to word so I can read it over and over in the future. I think you brought up many points that may help me on this issue.

[Steve Johnson]

You're very welcome -- and thanks so much for your kind response! In the interest of being thorough, I'd like to amplify on a couple of points.

I have also never understood how cactus plants like to be fertilized because I did not know the fertilizer sensitivity of cactus.

Well, it was a mistake I made for many years -- why should cacti need any fertilizer at all? Ooh, wrong, and important to understand why fertilizing is necessary. The primary nutrients for cacti are Nitrogen, Phosphorus, and Potassium (referred to in fertilizers as NPK). Nitrogen is an inert gas, although plant metabolism cannot absorb it directly through the air. N absorption takes place through the roots, and there are 2 methods. One is fixing N by bacterial action in the soil. Most plants can use it as a source for N because their soils are rich and moist enough to support that action. However, plants living in arid conditions are adapted to soils poor in the organic matter required for bacteria. Under those conditions, the action of minerals seeping through rainwater in the ground provides all 3 of the primary nutrients. That's fine when cacti in the desert get their only water from rain. But when they're under cultivation, they need other sources for N, P, and K. This is where fertilizers come in, and without it potted cacti are being slowly starved of the nutrients they require to thrive on. (The best ferts for cacti also include trace elements that would normally be present in desert soil minerals.)

You make a good point about fertilizer sensitivity. Cacti don't need much in terms of nutrient levels, so a little bit can go a long way toward reaping the benefits of a very dilute fertilizer. In fact fertilizing is like watering -- hard to under-do it, but certainly easy to veer too far in the opposite direction. With that said, it doesn't mean cacti can go without zero nutrients before consequences inevitably start to appear. Try letting it go for a year or two, and I don't think you'd be happy with the end result.

By the way, I don't think you could go wrong with my recommendation for using Dyna-Gro All Pro 7-7-7. I chose it after careful thought coming from several people whose experience I trust. Hope it works as well for you as it's working for me so far.

But I also have the coco fiber and pine bark. When I pot the cactus plants the pot fills with gorgous roots. The plant grows and looks great. Several weeks later or months I notice they just stop in their tracks. Then I look at the roots for health and the dirt falls apart. Then I repot them and the new roots fill the pot and the cycle continues.

If the roots keep degrading like that, I'd have to suspect the bark. Although pure Coconut Coir is organic, it comes without the evils you'll find in other organic materials. However, Coir mixed with any other kind of bark seems to be asking for trouble, so I'd recommend getting the pure stuff and mixing it only with mineral components. Dean's opinion on the matter is consistent with changes that are leading to bark toxicity in commercial mixes. I don't know how or why, but I'm sufficiently alarmed about what the implications are for using bark with cacti here in the U.S.

Anyway, I understand how frustrating it must be for you to be stuck with constantly replacing your cactus mix. Hopefully you'll be able to solve the problem and go over to a better mix. At that point replacing your mix should be a matter of years instead of months. However, acidified water will slow down the rate of Lime buildup, but won't stop it entirely. Long-term maintenance can help by occasionally flushing the soil with distilled water. I think once a year during summer should be enough, although I'll have to test this and see if more often may be advisable. Since you don't need to water with dilute fertilizer every time, you should time your flush to use it with distilled water only.

[martenfisher]

I have grown plants for most all my life. My first cactus was a little Cereus I got over 15 years ago. I still have it. I have been growing cactus in general for a little over 2 years. Some are easy and some are challenging. They rot if your not careful. Last season my cactus plants did super in pots and I had no problems the ones in the ground got nematodes and many rotted. This year I have this problem with the roots. Certain soil brands I will stop using and things like pine bark I will try to get out of the picture. Problem here is the bark from the paper plants from long leaf pines ends up in most all planting material. I have been making cuttings and I will be making even more cuttings and I wanted this root problem tackled before I keep going on. I need to pick up a PH meter and I am going to get a hose filter to try and catch the lime.