The worst thing about container gardening

[BoPeep75]

Can someone please tell me what they do to keep the soil levels from constantly slipping away several inches every year. It's not a problem for annuals since I top them up, refresh, add compost and start again every year. But I don't want to have to uproot my roses every year or two because they are sinking down along with the dirt. I also have "soft" things that die back like hostas that would be less troublesome to dig up and divide, but things like roses, lavender, or penstemon (or other things that don't like being messed with) are super-annoying. I try to add lots of perlite and compost and even though the soil drops (and I keep adding more), it goes down but is still easy to dig into. It's not hard-packed, and the plants are fine. It's been doing this for years, and every year I have to add more to a LOT of containers and raised beds. The raised beds are mostly annuals, and have open bottoms, but this is an issue with them as well. I can't transplant or "move up" my perennial baby's breath. I've tried before, and they HATE moving. It will die for sure. Any ideas appreciated. I've heard of perennial cloth, but only once. I have no experience with it and not sure how it would help.

 

[Meadowlark]

I would suspect the drain holes in your pots may be too large for the soil mix you have...do you notice soil coming out the drain holes?

On occasion, I have used sifted compost in a pot (very fine material) and it will almost always rapidly drain out the pot drain holes. To slow that down I like to use decayed organic matter ...old rotting wood particles in the bottom and with that I never have a problem losing soil mix.

Another less dramatic factor might be the compost itself decaying. Even "finished" compost continues to decay although slowly.

I have about 20 or so large containers that I grow veggies in continuously. Each of them is lined in the bottom with old decayed/decaying wood. I never loose soil in those.

 

[Martin Mikulcik]

It's dropping because microbes are converting the organic matter back into CO2. Use inorganic soil.

 

[BoPeep75]

I would suspect the drain holes in your pots may be too large for the soil mix you have...do you notice soil coming out the drain holes?

On occasion, I have used sifted compost in a pot (very fine material) and it will almost always rapidly drain out the pot drain holes. To slow that down I like to use decayed organic matter ...old rotting wood particles in the bottom and with that I never have a problem losing soil mix.

Another less dramatic factor might be the compost itself decaying. Even "finished" compost continues to decay although slowly.

I have about 20 or so large containers that I grow veggies in continuously. Each of them is lined in the bottom with old decayed/decaying wood. I never loose soil in those.

This is possible. I have been known to drill extra drain holes occasionally. I have not noticed much coming out though. I have recently started adding the wood chips and sticks I have chopped up from pruning to the bottom of my pots. That's kind of a new development, so not sure how it will do in the long run. I like the idea of it, but I assumed the breakdown of the wood would also cause it to shrink down so that's why I hadn't tried it before. All of my containers do this, but I feel like it's more noticeable in the bigger ones or raised beds. Most of my vegetables are annuals, so it's not a problem to top up, but my asparagus bed is very low at this point since I don't want to cover them up much. I feel like the worms and roly-polys are dragging off my dirt

 

[BoPeep75]

It's dropping because microbes are converting the organic matter back into CO2. Use inorganic soil.

If you use inorganic, do you have to fertilize all the time? I haven't ever considered this because it seems like it would be constant watering and fertilizing. Do you have success with edibles or ornamentals?

 

[Martin Mikulcik]

No, once a season is sufficient, 2-3 times is better. I have success with everything using dirt out of my yard for the most part. We have a nursery in Kentucky where our potting mix has been a blend of field dirt and perlite and a sprinkle of NPK but the perlite is mostly to make it lighter because new pots are made flimsy. It also helps with drainage but with proper watering it doesn't matter.

And we got a dozen semi loads of perlite from a second cousin who manufactured it way back before they had a use for the fines

There's nuances with soil pH and cacti soil for example could use being fast draining, and sphagnum is nice for starting seeds, and rooting cuttings but for 99%, the natural silt is sufficient. God made the dirt and put the plants in it and people try to make better dirt

If you look at fields they aren't dumping loads of compost on them, and they get really really good yields. Compost is good and i do use it but big farmers can't be bothered

Here's a couple pictures in action

A Japanese maple i potted after assessing cold hardiness and a sage i forgot to plant. Well I've really forgot about both of them and they're still alive and i can't tell you for sure if i even watered them last year. They also aren't rooted in the ground

But i will say if want actual good yields on crops you will need a very big pot to do as good as straight in the ground

 

[BoPeep75]

No, once a season is sufficient, 2-3 times is better. I have success with everything using dirt out of my yard for the most part. We have a nursery in Kentucky where our potting mix has been a blend of field dirt and perlite and a sprinkle of NPK but the perlite is mostly to make it lighter because new pots are made flimsy. It also helps with drainage but with proper watering it doesn't matter.

And we got a dozen semi loads of perlite from a second cousin who manufactured it way back before they had a use for the fines

There's nuances with soil pH and cacti soil for example could use being fast draining, and sphagnum is nice for starting seeds, and rooting cuttings but for 99%, the natural silt is sufficient. God made the dirt and put the plants in it and people try to make better dirt

If you look at fields they aren't dumping loads of compost on them, and they get really really good yields. Compost is good and i do use it but big farmers can't be bothered

Here's a couple pictures in action

View attachment 113308

View attachment 113309


A Japanese maple i potted after assessing cold hardiness and a sage i forgot to plant. Well I've really forgot about both of them and they're still alive and i can't tell you for sure if i even watered them last year. They also aren't rooted in the ground

But i will say if want actual good yields on crops you will need a very big pot to do as good as straight in the ground

I have lately been using dirt from my yard and making my own mix as well and that works as good or better than bagged potting mix. I do grow most of my things in-ground if they can be strong enough to survive this vicious Bermuda grass. That's the main reason I grow in pots (and raised beds for food garden). I have spent too many hours of my life on trying to remove or fight the Bermuda. I have managed it in certain areas, but when Bermuda starts trying to climb the roses and you have to dive into a huge thorny bush to weed it out, it's not worth it. I agree you can't beat God's handiwork, and I don't even like growing in containers, but I do it because of the weeds and it's also one less thing for my husband to mow around or worse, for him NOT to mow around because he's forgotten it's there. So I keep a bunch of containers on my patio, but I do have a lot of things in-ground as well. I try to use compost a lot because it's easier for me to make compost than me to find dirt. I only have so many places to dig on the property, and I don't trust what people use or spray on their own land to just go get fill dirt that I could amend. I love the bigger plants because their root systems can survive some drought and neglect, but I also love the prima donnas, and that's what causes me to micro-manage in a container situation. I'm thinking of stuffing some small bits of net in any large drain holes to keep any soil from moving out that I might not be noticing. Maybe that and adding even more perlite/vermiculite or something that wouldn't break down would help.

 

[Martin Mikulcik]

Landscape fabric holds dirt really well, we use it to make fabric pots but it is pricey

My condolences on the Bermuda

 

[DiggersJo]

We top up a little and often avoiding the base of the plants. For some, every other year or so we will carefully dig it/them out and reset the plant/s with new growing medium.

 

[jbclem]

Given your liberal use of compost, I would suspect that it is decaying and compressing quickly. And most commercial potting soils are peat based and soil microorganisms turn "peat to soup", and it compresses even more. Using pine bark fines in your potting soil mix would probably help with your problem .

Al's well known potting soil mix, the 5-1-1 mix, uses 5 parts pine bark fines, 1 part peat moss, and 1 part perlite. Conifer bark is much slower at breaking down and therefore the soil levels in the container don't drop as quickly.

You can learn a lot about potting soil on Houzz.com (the Container Gardening section) and Al Tapia's posts. A good introduction to the 5-1-1 is at this link:

Tapla's 5-1-1 Container Mix in More Detail

I recently joined the forum and discovered Al's 5-1-1 Mix, but I had several questions that Al was kind enough to answer by email. I also found the answers to other questions in several different threads. I thought it would be useful to organize all of the info in one place so that we could have...

www.houzz.com

and the Q&A's at the end are full of good information.