Split At Base - Pachycereus weberi

[bfh]

Hi!
Hoping someone can help identify potential causes and concerns. There is a new split at the base of my newly acquired Pachycereus weberi.
- repotted 9/29
- watered 10/19
- noticed split today 10/26

Thanks!

[greenknight]

Minor water cracking, leave it dry until spring and it should heal just fine. When you resume watering, water it lightly for a while before you give it a full watering, that should prevent more splitting.

Cacti can split from overwatering, or from being given a big shot of water when they're very dessicated - I'd guess the latter is the case here. This is very minor, keep water off of it to avoid the risk of rot and it should be no problem.

[bfh]

Thanks!

[Steve Johnson]

Hi bfh,

I noticed a few problems in your photo:

• Pachycereus weberi and the cactus to its right -- pot depth may be okay, although it depends on how deep the roots are. The diameter is way too big for them. There should be a margin of 3/4"-1" around the base or the root ball, whichever is widest. Believe it or not, pieces of styrofoam lining the pot can be used to compensate for overly-wide pots.

• The plants need to be centered in their pots, not way off to one side. What you're doing leads to highly uneven distribution of water going to the roots. Since they essentially "wick up" water during the spring-summer growing season, you'll find that the roots near the edge of the pot won't get enough water, while the other side of the roots will get too much (quite possibly leading to rot). This is going to be a problem with big pots, although you can get away with off-center cacti in small pots.Even so, it's best to center them.

• The cactus to the left of the Pachycereus shows severe yellowing -- that's chlorosis caused by long-term sulfur deficiency.

• A recommendation with regard to your terracotta pots:
  
  https://www.cactiguide.com/forum/viewtopic.php?t=45833
  
  When growers rely on evaporation through porous clay pots to dry out the mix, they're using the wrong mix.

I don't want to assume that's the case for you, so information about your mix would be helpful -- ingredients and proportion of each ingredient. Are you fertilizing? If so, please give me the fert's guaranteed analysis. We have a professional horticulturalist by the screen name of MikeInOz -- the best explainer of fertilizers we've ever seen, and I learned a lot from him. I'm doing my small part to "pay it forward", so if your fert doesn't pass muster (or you're not fertilizing at all), I can give you some guidance on finding a fert that's suitable for cacti and succulents.

If you're up for some changes to your growing practice, there isn't anything you need to do while your cacti are dormant this fall and winter. Call it planning in advance -- the recommendations I offer are things you'll be able to implement once the next growing season begins.

[greenknight]

True - while they don't need to be perfectly centered in the pot, they should be fairly close to it.

The pot being a bit large probably contributed to the cracking, since it held an excessive amount of water.

While there's no urgency to do it right now, you don't have to wait until spring to repot if you don't want to. Since you shouldn't water right after repotting anyway, doing it in the dormant season and leaving them unwatered until spring works just fine. Whichever works for you is okay, as long as you repot with dry potting mix.

[Steve Johnson]

Since you shouldn't water right after repotting anyway, doing it in the dormant season and leaving them unwatered until spring works just fine.

Actually, there are a couple of advantages to repotting in fall and winter as long as A. this is done during periods of sunny weather, and B. the plants are completely protected from rain at all times:

• Cacti undergo a certain amount of transplant shock when they're being repotted in the growing season. That's why growers need to let the roots of their plants settle in for 2 weeks before watering. Cacti being repotted in the dormant period will sleep through whatever transplant shock they might get if they're repotted in spring or summer.

• When cacti are unpotted in the fall or winter, growers can leave them in their bare-root state without the need for repotting right away. This gives them plenty of time to:
  • Clean and inspect the roots. If the root system isn't as extensive as it should be for the species, chances are that the pot is too big for the plant. Now would be a good time to either look for a smaller pot, or line the current pot's sides and bottom with styrofoam.
  • Check for root mealybugs. This is a wintertime problem because root mealies prefer dry mix, and they thrive in the plant's period of dormancy.
  • Make a note of the following dimensions -- the plant's base or root ball (whichever is widest), and length between its soil line and the lowest root. Add 1.5"-2" to the width plus 3/4"-1" to the length, and you'll have the correct size of the pot you should look for.
  As Spence said, cacti don't need to be perfectly centered -- the main point is to make sure that the pot's diameter gives them a margin of 3/4"-1" all the way around. Finding the "ideal" pot size for the plant may not be possible. If you go a little bit smaller, that's fine. But if you can only go bigger, styrofoam lining the sides (and bottom if the pot is too deep) works just as well. By the way, the tip about using styrofoam comes from MikeInOz.
  
  Okay, what happens if you unpot cacti in the fall or winter and you come to find out that you have a root mealy problem? The answer is easy -- soak the roots in a 2% soap solution for about an hour, then let them dry out before you repot. Plain dish soap is fine, but insecticidal soap is better. Let the water warm up before you add in the soap. Rinsing the roots right after you do the soak will be counterproductive -- dry soap residue protects them from any further root mealy attacks while the cacti are dormant.
  
  For those of you who keep your cacti in your house or a greenhouse during fall and winter, you can unpot and repot them whenever you want.

[greenknight]

Right; I like dormant repotting, no interruption in growth. The growing season here is short.

I try to get the cacti centered, never quite turns out that way. That's why I mentioned it - close is good enough.

Styrofoam works, or you can use rocks -just don't put a layer of gravel in the bottom, having layers of different materials interferes with drainage. There should be potting mix between the stones or foam chunks to provide drainage channels.

Styrofoam is light - makes the plant easier to move around, but also less stable.

[bfh]

This is super helpful info!
I'm going to do some winter repotting to get ready for the spring.
- The pachycereus has a "J" shape to it including the rootball, which is why it is offset in the pot. The root ball is centered in the soil. I'll repot it and post a photo of the process.
- the yellow cereus: this is about 6 years old and I've completely neglected it, outside in full sun and bay area winter rain, 4 years is the same pot / soil. So this one is ready for a repot!
- soil mix: i've been using a cactus mix from Cactus Jungle (a local shop), and have recently moved to 1/2 cactus mix and 1/2 lava scoria
- fertiziler: I would love some tips.

[Steve Johnson]

This is super helpful info!

Excellent!

The Pachycereus has a "J" shape to it including the rootball, which is why it is offset in the pot.

Sounds like it was being grown in a pot that was too shallow for the roots, and they had to go somewhere -- as in sideways. If you purchased the Pachycereus from a nursery, their plastic nursery pot wouldn't be deep enough. (This is a problem I've seen with nurseries.) When you unpot the plant, clean the soil out of the roots as thoroughly as possible:

• Take an empty container and fill it with water. Gently swish the roots around to float out the soil. If the water gets really dirty, throw it out, fill the container with clean water, and keep swishing the roots around.

• Take a blunt object (q-tip handle, knitting needle) and tease out the roots until they hang down freely. Be sure to dig out any soil hiding up in the root ball. This prevents the possibility of rot which can be a problem if a bolus of soil is left right below the base. Also be sure to remove residual soil and bits of organic material clinging to the roots.

• Let the roots dry out thoroughly before repotting in fresh dry mix. Don't even think about watering until spring.

The process I just described is standard practice which should be followed whenever cacti are repotted. Once the roots of your Pachycereus are untangled and hanging down freely, you'll have a better idea as to the pot diameter and depth that'll be suitable for it.

Soil mix: i've been using a cactus mix from Cactus Jungle (a local shop), and have recently moved to 1/2 cactus mix and 1/2 lava scoria.

I took a good look at Cactus Jungle's cactus mix:

• "Coconut Coir, Lava Scoria, Pumice and Composted Rice Hulls.
  "Fortified with our slow-release Cactus Meal fertilizer, which includes Alfalfa, Kelp and Neem Seed Meal, Oyster Shell, Azomite, and Fish Bone Meal.
  
  "Great for all cactus and succulents, citrus, and any plants that need a fast draining soil."

First of all -- no loam in the mix, so that isn't soil in the true sense of the word. Wouldn't be an issue if it weren't for the fact that coconut coir causes too many problems. Here's what our horticulturalist-in-residence MikeInOz has to say about it:

I wouldn't use coir unless I absolutely had nothing else to use. And probably still wouldn't. It has many problems. 1, It is often high in chloride, this can be mitigated by rinsing several times. 2, It has very low S and Ca and very high K. So much so that it can cause Mg deficiencies unless it is amended. Soaking in CaSo4 or MgSo4 and CaNo3 after rinsing can help. 3, Orchid growers were initially told that Coconut was the medium to end the use of all other mediums and went ahead and used it at full throttle. What did they find? Most had great results for a start and then found all kinds of deficiencies showing up later, severe chlorosis, death of roots and death of the entire plant in many cases. 3, Fungal mycelium LOVES coir unless it is completely consumed by composting. It thrives in it and if it gets a foot hold, the entire root ball can become choked with white mold and dead roots. Fungus tends to proliferate in dry, acidic conditions rather than moist alkaline ones where bacteria usually dominates. 4, It should have Fe and Cu added to it. 5, It is sometimes prepared from green husks and can contain unwanted plant hormones. Having said all that some people say they have used it with success but I think we should be aware of it's possible problems. It is interesting to note that some commercial Dutch nurseries said they never want to have to see or deal with coir products again.

But wait, there's more!

Coir dust is used successfully in mixes for bedding plants and general mixes where it is fed heavily (EC is high) and it is kept moist, but for mixes which dry completely you can have the troubles I mentioned. As long as the Ca, Mg, and S is balanced with it's high K, and the chloride is leached out it works ok. It actually has very good properties like high AFP and wettability. But because it is made from raw un-composted material, and some batches are exceptionally bad, when something goes wrong it goes wrong spectacularly. Another problem is that it holds water for such a long time, you might think your mix is dry and needs water when it doesn't. I cannot understand why cacti growers would use it.

I'm not thrilled with Cactus Jungle's version of fertilizer either. Cacti and succulents need a mix that's completely different from what's used for citrus, and yet nurseries seem to think that they can all grow perfectly well in the same stuff -- a big red flag there. We also have a problem with scoria, so check this out:

https://growertoday.com/scoria-and-pumi ... t-growing/

I've been successfully growing cacti with a soilless 60% pumice-40% granite gravel mix for over 12 years, and I highly recommend it. There are only 2 downsides:

• Cacti and succulents needs to be fertilized every time they're watered in the growing season. Not much of a downside, and IMO the upside in terms of growing quality is worth the effort.

• The roots of some species won't grow well in a pure mineral gravel. Examples are Tephrocactus (their very thin root systems need soil in the mix) and heavy feeders like Echinopsis, Trichocereus, etc.

Regarding fertilizer, I'll give you a couple of recommendation, so the one you choose depends on how far you want to go with this. Unfortunately I don't have enough time to go through a properly-detailed discussion of those choices now, but I'll post them for you soon. Nice thing is that you'll have plenty of time to make a decision as you prepare for the upcoming spring-summer growing season.

[bfh]

Thanks for all of the wonderful advice and wisdom! Here's an update on the Pachycereus weberii.

- I un-potted it and let it dry for 7 days
- repotted yesterday with a grittier mix: about 2 parts pumice, 1 part granite gravel, 1 part lava scoria, 1 part Cactus mix. The shape of the plant makes it hard to minimize planting media, there is a lot of space to fill above the roots. So i underpotted it a bit.
- And yesterday afternoon threw together a winter shelter for the recently re-potted, just in time for a light drizzle to start

[Steve Johnson]

Here's an update on the Pachycereus weberii.

- I un-potted it and let it dry for 7 days
- repotted yesterday with a grittier mix: about 2 parts pumice, 1 part granite gravel, 1 part lava scoria, 1 part Cactus mix. The shape of the plant makes it hard to minimize planting media, there is a lot of space to fill above the roots. So i underpotted it a bit.
- And yesterday afternoon threw together a winter shelter for the recently re-potted, just in time for a light drizzle to start

Hi bfh,

The repot looks good, and pot dimensions for your Pachycereus should be fine. Your new mix has better aeration, so don't be surprised if the roots fill the pot as they grow in more during the next growing season. The only thing I might recommend would be nonporous pots (plastic, glazed ceramic, or terracotta sealed with acrylic paint), but I took a look at your local climate according to Wikipedia:

• "Berkeley has a warm-summer Mediterranean climate (Csb in the Köppen climate classification), with warm, dry summers and cool, wet winters. Berkeley's location directly opposite the Golden Gate ensures that typical eastward fog flow blankets the city more often than its neighbors. The summers are cooler than a typical Mediterranean climate thanks to upwelling ocean currents along the California coast. These help produce cool and foggy nights and mornings."

Based on what I'm seeing, I think the porous clay pots will be required to help dry out the mix in a timely manner as you give your cacti regular deep watering over the spring and summer. The roots of desert cacti need to go completely dry between waterings, so my default recommendation there is deep watering every 2 weeks in the growing season.

By the way, good call on that winter shelter.

Thanks for all of the wonderful advice and wisdom!

My pleasure!