Yet another soil thread

[1rainman]

I never noticed the problem other than in pots with small holes and no rocks on the bottom. Or maybe outside during Florida rainy season and a plant isn't root bound enough then the compost gets wet swampy rotty fungusy. The simple solution is sand or less compost. It's a big problem when rooting cuttings because they rot easily you need really good drainage. I tried pure perlite before and discovered even perlite can get soggy. Probably sand or a sandy mix with perlite is best for rooting. Citrus I think is easy to grow as long as you don't have a lot of mulch or soil that is too soggy. It's not super picky it can handle some dampness. Usually root rot is because of the little water container under the pot and or small holes. When I put my plants outside they don't have a water tray under them the water just drains out. And indoors I will let it sit in water some but often dump it. It's pretty easy to avoid root rot once you get the concept down. I never had any problems with miracle grow potting soil the drainage is good despite people saying it sucks. They sell miracle grow garden soil which is cheaper and junk maybe they get mixed up with each other. Though adding a small amount of sand is beneficial. Some grapes find potting soil too acidic others don't but 99% of plants do well in it.

[Millet]

The concentrated water layer at the bottom of every container, known as the perched water table, happens even if the container had no bottom at all.

[pagnr]

Here is an experiment to show air apace and water holding zones in pot media and pot height.
Take 2 identical bath or beach towels, representing the pot media.
Hang one vertically and one horizontally on the clothes line and soak with the garden hose.
Both will drain water to the bottom of the towel at the same rate.
Both will also quickly drain water from the top two thirds of the towel to the bottom. This area will be airy but moist for a while.
The bottom third of each towel will be quite wet.
Each will have an upper 2/3rds moist zone and a lower 1/3 wet zone.
Because of the different heights of the hung towels, the taller vertical towel will have a much deeper airy moist root zone than the flatter hung horizontal towel.
The same will apply if identical pot mix is used in different height pots. Tall narrow pots will have better drainage and a bigger ideal moist airy root zone than flatter squat pots.
You can get a good air and water holding balance by using taller narrow pots, and potting your Citrus roots into the top third of the pot.
The plant can be watered frequently, but the wet zone will below the plant.
As the plant grows it should draw more water from the pot and tap into the wet zone. Hopefully it will be big enough to use that water, and consume the saturated zone.

For a 3D version the same test can be done with identical kitchen sponges.

[poncirsguy]

You are correct but you won't oxygenate the soil like a vacuum does.

[pagnr]

True, but I could dry the towels with a hairdryer.

[Travillion]

...  However, I have found that Turface MVP and Peat is far superiors as a medium for container citrus trees..

Are you using MGGS or straight peat? I've used this for about 1 year and saw that roots are starting to get exposed at the top. I assume it's from the MGGS breaking down, and not the MVP. Should I just add more MGGS to the top, or more 50/50 mix? My tree is very happy in it, but man is it heavy!

[Millet]

I am using plain peat moss, however MGGS works just as well.  Actually, I would have used MGGS instead of peat, but I was out of MGGS so I just used regular peat moss. My mix is now going on 2 years and works great.  You should not have any trouble with either mix.  About the roots, I would just watch it and presently would do nothing.

[Travillion]

Thanks Millet!

[1rainman]

If I water heavily like a good soak it is in a sink, bathtub or outside. The water drains out good enough and the plant sucks up the rest. I have stuff in pots outside in Florida where we get a foot of rain a day and they are doing fine as long as they have sun and heat. I only worry about stuff that isn't rooted to the pot so the plant doesn't soak up the moisture yet. Have to be careful not to overeater. But good drainage and I don't worry about perched water tables. My dirt has a decent amount of perlite and sand though with some clay to get them through dry periods.

[Peep]

Next week I will start the repotting.

I just wanted to check if riversand is alright to use? From what I read it seems ok to use, but I don't want to make mistakes. https://www.brico.be/nl/bouwmaterialen/metsel-en-pleisterwerk/zand/rivierzand-0-4-mm-25kg/3392898

And I also thought of another interesting topic; what makes the best soil cover?

I sometimes used the pine bark as soil cover. I could also use the lava split. This kind of lava is said to not be ideal inside the soil mix, because it's too sharp for the roots, but maybe it's not a problem on top? Or will it be bad for the feeder roots? Or is it better to have no cover/mulch at all?  Or other suggestions for the best soil cover?

[pagnr]

I prefer riversand about the grade of brown sugar or above. 1mm to 2mm upwards. You could run the sand thru sieves and check the grades in it.
3 or 4 different mesh sieves ( even kitchen strainers ) will give you a good profile.
It can vary from lot to lot or source or season.
The pic looks ok, but you could possibly remove the finest particles and use them elsewhere, or mix in another ingredient to compensate.

[Peep]

I prefer riversand about the grade of brown sugar or above. 1mm to 2mm upwards. You could run the sand thru sieves and check the grades in it.
3 or 4 different mesh sieves ( even kitchen strainers ) will give you a good profile.
It can vary from lot to lot or source or season.
The pic looks ok, but you could possibly remove the finest particles and use them elsewhere, or mix in another ingredient to compensate.

Indeed, my plan is to buy this 0-4 mm size and sieve the finest particles out. I have a few different sieves so I'll have to try them out.

[1rainman]

I mulch my container plants with regular mulch because they are outside and dry out quickly. The mulch slowly rots and replenishes compost which the plant removes and mulch is cheap. When I didn't use mulch it just dries out too fast. Then I started adding clay too. But I'm in Florida right now and it's hot all the time. Normally mulch is not recommended on citrus because they like to dry out. But my container citrus would be bone dry after a few days of no water in summer so I mulched it. I never had any problems my plants are healthy.

[Peep]

Is it okay to use river sand that contains bits of seashells? Or can this be too much calcium?

[pagnr]

Is it okay to use river sand that contains bits of seashells? Or can this be too much calcium?

The rate of adding super fine Ag Lime and Dolomite Lime to Peat based and Coir based pot mix is 1kg to 2 kg of each per cubic metre, when mixing the pot mix.
This is to adjust the pH and supply Ca and Mg for a long period.
This is very fine ground powder, with a fast release rate for Calciim and Magnesium.
Intact shell and large pieces are going to be much slower acting.
Really it depends on the % of shell in the sand, the pH of the pot mix, and any other Calcium fertilisers, and the Calcium in your water supply all adding up to total Calcium.
You could probably sieve a sample of the sand and work out the % of shells.
Unless the % shells is high, it probably won't make much difference.
Do you have water snails etc in your Rivers ?
We get a few shells in our riversand, snail and mussel, but never that much.

Edit. possibly the most important factor is the % of sand you are using in the pot mix.
If you are using a large % of sand, the shells will factor more.
If you are using low % sand, ( say 2 to 5 % ),  the shells will be less in the total pot mix, and will have less effect.

[Millet]

For my trees I use calcium nitrate, either as a soil treatment or as a foliar spray.

[Travillion]

... However, I have found that Turface MVP and Peat is far superiors as a medium for container citrus trees..

Do you screen your MVP to a particular size?

[Millet]

I do not screen the Turface MVP.  I use it right out of the bag. The product comes highly uniform in texture.  I mix it with either peat or Miracle grow Garden Soil.  Both mixes are good, but blended with Miracle Grow Garden soil is even better.. 

[Travillion]

I do not screen the Turface MVP.  I use it right out of the bag. The product comes highly uniform in texture.  I mix it with either peat or Miracle grow Garden Soil.  Both mixes are good, but blended with Miracle Grow Garden soil is even better..

Thanks!

[1rainman]

Though shells exist for thousands of years before decaying. To give you an idea that the amount of minerals leaching out is a trace amount. But in Florida since the whole ground is full of shells we have a lot of calcium and lime in our river and well water.

[Peep]

Thought I should update this a bit.

I went with the equal parts of:

coco coir
light potting soil
0-4 mm river sand
2-6 mm perlite

I didn't end up sifting the sand, too much hassle.
I did wash the coco coir with epsom salt.

When experimenting by changing the ratios a little bit, like for example by adding some more sand, I didn't really have a reference as to which version was better or why. So I kept it at 25% of each.
Will have to see how the plants do this year, and next spring take some of them out to inspect the roots.

Bucket of each material in a mixing tub:




Did about 25 pots so far with the new soil. Reused the old potting soil with lava (that is supposed to be too sharp) for some of my less important citrus plants, so it can still be compared.


Next up will be repotting the new grafts so they can go outside. I don't think it will freeze again this spring.

[Travillion]

Cool! Looking forward to hearing your results after a bit of time!

[kumin]

I used straight Coconut Coir to germinate Poncirus as well as Poncirus hybrid seeds. Immediately following germination all the seedlings began dying, showing salt toxicity. The majority of the seedlings were unpotted, then repotted in a peat based media. The Poncirus hybrids recovered quickest. Kabosu and Poncirus seedlings are recovering, but it's a slow process.
My understanding is that Coconut Palms thrive in saline water and the tissues have salts within the husk fibers. Which would explain why simple rinsing was ineffective. There was a suggestion to apply Calcium/Magnesium to buffer the salt content. Too much maintenance for me.

[Peep]

I used straight Coconut Coir to germinate Poncirus as well as Poncirus hybrid seeds. Immediately following germination all the seedlings began dying, showing salt toxicity. The majority of the seedlings were unpotted, then repotted in a peat based media. The Poncirus hybrids recovered quickest. Kabosu and Poncirus seedlings are recovering, but it's a slow process.
My understanding is that Coconut Palms thrive in saline water and the tissues have salts within the husk fibers. Which would explain why simple rinsing was ineffective. There was a suggestion to apply Calcium/Magnesium to buffer the salt content. Too much maintenance for me.

Yeah rinsing with water is supposedly not very effective. It was discussed a bit earlier in this topic, but it seems that magnesium would do the trick and that calcium is not necessary. So while I'm not a fan of the extra work, epsom salt was easy enough to find and I hope it helped enough to not have any problems. And I think it could help that the coco is only 25% of my substrate.

I let the dried and compressed coco coir bricks soak in the epsom water, then put it in a plant pot with holes so it could drain and flushed another bucket of epsom water through about 10 liter of the hydrated coco. After this I ran some regular water through it with the hose.   

[pagnr]

I used straight Coconut Coir to germinate Poncirus as well as Poncirus hybrid seeds. Immediately following germination all the seedlings began dying, showing salt toxicity. The majority of the seedlings were unpotted, then repotted in a peat based media. The Poncirus hybrids recovered quickest. Kabosu and Poncirus seedlings are recovering, but it's a slow process.
My understanding is that Coconut Palms thrive in saline water and the tissues have salts within the husk fibers. Which would explain why simple rinsing was ineffective. There was a suggestion to apply Calcium/Magnesium to buffer the salt content. Too much maintenance for me.

The salt toxicity could also be pH issues and air space / water logging issues. The Ca / Mg would also up the pH
I tried germinating some Syzygiums in 100% coir. Some species failed but some did ok.
Same symptoms as you say.
I usually use 30 % coir and 70 % coarse sand ( including any perlite, grit, zeolite etc ) for cuttings and seed germination.
That seems to avoid these issues.