Potting mix amendments

Edited to add: This thread was intended to ask questions about soil ammendments, but I ended up off-topic.

Sometimes when people post about using the 'gritty mix' and the '5-1-1' mix, they also add other things, like lime or gypsum. Is there really a need to do this with general use or is it dependent on the plant or plant type, and what their specific needs are? I plan, at least for now, to continue using the 24-8-16 MG I have now.

Also, I am wondering if there are any real advantages to 'gritty mix' vs. '5-1-1'. Can anyone tell me why they prefer one over the other?

I've gotten the cherrystone, the pine bark, am waiting for the turface I ordered. In the mean time, I happen to have perlite, so just figured I would ask, since maybe I can keep both mixes on hand for different purposes if needed.

Thanks so much. I've already gotten so much information from this great site, that I had to subscribe.

-Shari

This message was edited Jan 27, 2012 5:30 PM

The pH of the gritty mix is fine as it is, so it's best not to add dolomitic (garden) lime to it as a Calcium (Ca) and Magnesium (Mg) source. Most peat-based soils and the 5:1:1 mix utilize lime because the low starting pH needs adjusting upward, which the lime does, and because it does double duty as a source of Ca and Mg.

Gypsum [CaSO4] supplies Ca and S(ulfur) without changing soil pH; so when you use fertilizers without Ca or without Mg, you need to find a way to include those elements so plants can grow normally. The best way I have found to do that when using the gritty mix is to simply use a fertilizer that has ALL the essential elements, including Ca and Mg. I use Foliage-Pro 9-3-6, because it DOES contain all the essential nutrients, and because it doesn't supply its N in the form of urea. Nitrogen from nitrate sources helps keep plants compact and bushy, which is a considerable plus for houseplants often starved for light.

So, using the gritty mix and fertilizing with MG 24-8-16, you would add a tablespoon of gypsum to each gallon of soil when you make it. Then, when you fertilize, add 1/2 teaspoon of Epsom salts [MgSO4] to each gallon of fertilizer solution when fertilizing at full strength, and 1/4 teaspoon if fertilizing at 1/2 strength. The Epsom salts acts in the way as the gypsum, supplying Mg and S without changing pH.

I hope that covers your questions. ;-)

Al

Thank you, Al. It does, with the exception of why you personally choose 'gritty mix' over '5-1-1'. I would still love to hear from others about this subject as well.

Thanks!!

-Shari

I started studying soil science about 25 years ago, immediately after I'd failed in my first attempt at bonsai. My efforts led me toward the approximate conclusion that the more aeration the grower could tolerate in container media, the better the plant would like it. I started to figure out how to best build a soil like that & eventually came up with the gritty mix first. I recognized that perched water, which is the water that occupies the soggy layer of soil near the bottom of the pot when soil particles are too small, killed roots, and was the cause of my struggling. I wanted a soil that would ensure a healthy environment for roots from top to bottom of the pot, that held its water INSIDE of soil particles instead of in between them, was durable/long lasting, and adjustable for water retention. Those properties are not easy to achieve in a container soil, but the gritty mix does it very well - better than any soil I have ever built or seen, which is why I prefer it over the 5:1:1 soil for houseplants.

However, I go through a LOT of soil. I repot more than 200 plants that range in soil volume from about a quart to over 10 gallons each. I use about 20 bags of Turface & 15-18 bags of grit each year, and about 20 cu ft of fir bark for just my bonsai and houseplants. I realized that my short term plantings (mixed garden display plantings & veggies) didn't need a soil that would last for years, so I applied the same principles to a soil with a higher fraction of organic particles and more water retention, and came up with the 5:1:1 mix. It really isn't much different than what many nurseries use for their plant material. It offers FAR better aeration and drainage than soils based on peat/compost/coir and that include a large total fraction of fine particles.

At least 90% of the problems that growers end up asking for help with are traceable to soil choice, and I include diseases and insects right along side poor growth, poor vitality, and spoiled foliage. A soil too water retentive either causes root rot or compromises root function, or it ensures soluble salt build-up if you water in sips to avoid the aforementioned. There is no escaping that assessment because you can't have it both ways.

Most growers using bagged soils made from fine particles, albeit unwittingly, are trading their plant's potential growth and vitality for the convenience of soil from a bag. I'm not saying that because I'm judgmental. I want to help the people who want help, but I'm not interested in twisting any one's arm to change anything they don't want to. Facts are facts, however, and all I'm interested in is getting the information out there that allows growers to make an informed decision about what they want to grow in, instead of watching them try to deal with poor soils because they think they are the only choice. I've seen literally thousands of growers call themselves failures, when it's probably a lot more accurate to say their soil failed them ..... they just didn't have the knowledge to understand how significant the difference could be with such a subtle change in perspective.

Al

Thanks for making things so easy to understand.

I did get my turface today, and made some potting mix, and repotted 7 plants. I took photos of them all after repotting them, so I can take photos again after a week to compare how they reacted to the new mix. I did the turface (all pro), cherrystone grit, pinebark fines, and gypsum.

I watered them all using half strength MG 24-8-26, with a little epsum in it. The only things I am left wondering are if I am going to need to feed every time I water, if I should use less fertilizer or not given it's winter, and how I'm going to know when they need new watered, since I can't tell by sticking a finger in the mix.

Funny thing is, apparently I couldn't tell before either. One of the plants that I repotted into the new mix tonight.. I stuck a finger in there before I took it out of the pot. I felt very dry. When I got the root ball out, it was rather wet at the roots. I realized that I've been most likely over-watering this plant since I got it.

Is this a mix that even my african violet will like? So far I have repotted a spider plant, an areca palm, a purple passion, a snake plant, a ponytail palm, a dracaena of some sort, and a pothos into it. Next, I plant to do both of my "bonsai" ficus.. (they came from people who bought them at walmart with glued on rocks), by Chinese evergreens, peace lilies, and dieffenbachias.

Thanks again.

-Shari

P.S. will this mix do away with fungus issues? I am noticing white funk starting to hang out on top of the plants that stay wet the longest. (largest pots)

This message was edited Jan 25, 2012 11:01 PM

Did you use a product called Allsport? I'm not familiar with Allpro.

Whether you can or should fertilize every time you water depends on your soil and watering habits. If you're flushing the soil at every watering, you can fertigate @ low doses every time your plants need water. If you're using a heavy soil necessitating watering in sips, you can't. For a maintenance dose (every time you water), use 1/4 tsp/gallon; otherwise, use 1/2 tsp per gallon every other week. You may need to increase the dose a little in the summer.

Use a sharpened wood dowel stuck in the soil to see if your plants need water. If it comes out dry, water. If damp - don't. You may need several to test multiple plants.

AVs will like the soil, but they might not like the fertilizer. I'm not an AV expert, but mine seem to much prefer their N from nitrate sources, which is another plus for Foliage-Pro 9-3-6 (urea free) fertilizer.

Fungus issues? The white crusty deposits of dissolved solids left behind when water in the pot evaporates?

Some tips: Houseplants are better repotted in the summer - between Father's Day and July 4th is about the best time for most, with only a few exceptions.

It's best to withhold fertilizer for a couple of weeks after repotting because it promotes better root colonization of the soil mass.

Best luck!

Al

Yes, sorry I meant "Allsport".

I'm posting a photo below of the soil condition. It seems as though yesterday it appeared somewhat 'fuzzier' than today, but three of my my plants, all in deeper pots, with heave soil have this, and yes I have been giving them 'sips'. I know that the soil is dense enough that to flush them would only mean long-standing perched water. The spider plant that I repotted last night had been getting a white (almost) crust on it that I had scraped off and it came back, I'm sure from salt build-up. It looked slightly different from this stuff, although this may be the beginnings up the build-up?

I know the spider I repotted last night had several gross squishy roots on it that I removed and cleaned off the old soil before reotting in the gritty mix, and the leaves are starting to stand back up some and it already looks healthier over-all.

I don't plant on repotting everything right now, as I'm sure several of my plants wouldn't be too pleased with me, but just the ones that are already looking stressed.. and maybe these ones with the white gunk on the soil. These include 2 snake plants, and a Chinese evergreen. I'd like to repot the 2 'bonsai' ficus now also, but will likely just do one of them, as leaves keep turning yellow and dropping, and it's down to few leaves now anyway. It has rocks glued on top of the soil.

I will likely switch my fertilizer when what I'm currently using runs out.

So I also get from your post that I need to use about 1/4 of the fertilizer I'm using in the gritty mix, but not for a couple of weeks after I repot. The sharpened dowel is a great idea, thank you.

I really appreciate your time answering my posts, I know you answer a lot of posts by other folks, and you end up telling most of us something that you've already said probably hundreds of times.

If you see something in my posts that is dead wrong, and you believe would be detrimental, please let me know. I value your input and help and the ability to weigh viewpoints more than I value a dead plant.

Thanks again.

Here is a shot of the soil in another pot.

Shari - To show you how much AVs love the Foliage-Pro 9-3-6. Here is a pic of my mini-chimera. It gets fertilized each time I water at 1/4tsp/gallon of water. It is a bloomin fool !!!
Whatever Al says you can take to the bank!

Linda

What a great looking plant, Linda. Strong work! ;-)

I'd say the white deposits on top of the soil are dissolved solids left behind from water evaporating from the soil surface. You can scrape them off if you like, and top off with a little fresh soil. Are there any areas of the plant that feel sticky? I'd like to eliminate the possibility that any of the cottony looking white areas on the plant are mealybug. Do those areas on the plant feel dry & crusty, like mineral deposits, too?

If you'll be fertilizing at every watering, you need to reduce the concentration of fertilizer a lot. 1/8 - 1/4 of the recommended dosage, depending on temp, is a good range. Don't fertilize with MG if the temperature is below 55*, as you risk the possibility of ammonium toxicity.

I'm always happy to answer all the questions time allows, and you seem to be 'getting it'. Once you get used to using the gritty mix, you'll see for yourself how easy it is to take care of your plants.

Take good care! TTYL

Al

Very pretty, Linda. My AV hasn't bloomed at all since I've had it which is about 2-3 months.

Al- looks like it is salt on the soil, the drier the soil got, the whiter it got.

I repotted the one 'bonsai' ficus last night that had yellowing leaves and was dropping them. There were drainage holes, however it never drained, I guess. When I got it out of the container, probably a full cup of water drained out of the soil right away. After getting it potted again in the gritty mix, I noticed tiny white rice-looking spots on the bottoms of a few leaves. They are very very VERY small. This plant also had spider mites to begin with, though I don't see any now.

I haven't found any sticky spots on any of the plants. I checked thoroughly.

So now I have a clear picture that I'm in a load of (you know what) above my level of plant knowledge, and all because I wanted some plants in my house. I'm not
going to give up on them though. I'm just glad there are people out there so willing to help out people like me.

Not sure how you keep and have the ability to run a glass co. too, Al. I only have about 40 plants and it seems it's been one thing after the other for the last couple weeks. Seems like eveything was awesome til I got the new 7, which included the big Scheff.

So this thread turned totally off-topic, sorry.

I took a couple of pictures of the 'white rice-looking' spots. Are they left-overs from the spider mites, or something else ya think?

The leaves in the photos are 1.5 inches long. The spots aren't on every leaf, just a few of them.

one more photo, of a different leaf on the same plant.


Edited - Guess it's the same leaf, sorry.

This message was edited Jan 27, 2012 5:29 PM

You're lucky you caught it (bonsai). Hopefully it was in time.

Cant see the white things well enough. Do they look like the shed skins of insects after molting? I wish I could help more. Maybe take the leaf to a greenhouse (in a ziploc bag) or to your county coop ext service for a positive ID. In the meantime, it wouldn't hurt to treat with an all season horticultrural oil or neem oil.

I'm hear pretty regularly, and I can usually offer good advice on things related to soils, nutrition, cultural influences, and physiology. I'll keep an eye out for you - or you can find me on the sticky thread. I'd say that pest ID is probably the area where I need the most work.

My company is 35 years old, and I have some good key people, so they really only need me to bark occasionally & keep the wastebaskets emptied. ;-) Later.

Al