Haven't used those....but I have used plastic pots turned upside down to take up space. Also heard of folks using plastic water bottles, soda bottles, et cetera. Here's a shot of a half-barrel with some overturned pots to reduce volume of mix required.

Josh

Pip, do you realize how large a half-barrel is? Those are 1-gallon pots swimming in that volume. Often, when using a large or decorative container, we don't really need the root-space to go so deep....and to fill the entire volume would be costly.

Josh

I stand by my statement. Your better off with a smaller pot, and potting up as needed.

What's the point of "removing" 4 gallons from a half barrel anyway?

For those considering this, what would work for an annual in this case could be bad for a perennial. Due to potting up. You could jump to a large container from the beginning but that's not a good idea due to the mix taking too long to dry.

But to each their own, I'm just biased from dealing with plants stalling from potting up too large. Tried to save a buck and only buy the size I eventually wanted them to be in. Not the one in between.

The point is reducing the overall volume that must be filled in the lower layers (saving money), reducing overall weight of the planting (for ease of movement, less stress on a deck, et cetera), and also elevating the mix level for easier planting/positioning (added bonus).

For this particular planting, I had been up-potting a fern for several years. I had to go bigger - wider, really - so I wouldn't have to re-pot for a good long while. This upper volume has allowed the fern to flourish and achieve great size.

Josh

Just snapped a pic....this is my Woodwardia fimbriata, common name Giant Chain Fern. This year's fronds are approaching 5-feet in length. It is truly a monster. I look forward to seeing exactly how big it will get.

Josh

Back to the Q about what to use as a soil displacer in the bottom of a larger pot, I just used small plastic salad greens containers for the bottom of 5 gallon buckets ... a perfect fit.

I just stack up sheets of Styrofoam to take up the space. Although someone one the board uses a bunch of plastic waterbottles which would work great if I actually went through bottled water. Unfortunately I don't have anyway to recap beer bottles. lol.

A large indeterminate tomato plant can use all the room you're willing to give it. I grow them in 25-gallon pots, and I think they produce more tomatoes that way. I have a few half whiskey barrels, which hold about 25 gallons or a little more than 3 cubic feet, and I have grown tomatoes, melons and cucumbers in them. I know it can be expensive to buy that much potting mix, but I use 5-1-1, which only costs me about $3 a cubic foot. It's less than that over time since I reuse about half the mix each year.

For this particular planting, I had been up-potting a fern for several years. I had to go bigger - wider, really - so I wouldn't have to re-pot for a good long while. This upper volume has allowed the fern to flourish and achieve great size.

You do realize that you only delay the roots reaching the sides and bottom of the pot by weeks right? That most of your soils volume is root free when you don't gradually pot up?

I'll repeat myself for those reading and considering other options. You can save weight and not loose root volume by mixing in 50% or more perlite. And read up on the pros and cons of potting up vs just starting in a large container.

Pip, I'm not sure whom you're lecturing, about what you're lecturing, or why. You quoted me in your response, but I don't understand your point or how it pertains to me.

Every time that I've re-potted my fern, as an example, the potting mix has been thick with roots. With this particular planting, I'll have to begin removing crowns to provide room for new growth.

Saving weight is just one consideration....saving money is another. Perlite has become more costly lately, but using old bottles, pots, et cetera, has not. That said, I do use a considerable amount of Perlite in large plantings.

Josh

I have 2 - 25 gallon ceramic containers I use in the garden to grow potted trees. There's an overturned 5 gallon bucket in both of them as ballast - to take up space so I don't have to use as much soil - like Josh illustrated. Ballast in the bottom of pots is especially helpful when you're using a soil that supports significant amounts of perched water. A perched water column is always going to be the same ht for any given soil, regardless of the ht or shape of the container; so, if we can use ballast to reduce the volume of SOIL within what would be the PWT, we can reduce the volume of PW the soil holds.

If you use a soil that holds no perched water, there is no advantage or disadvantage in filling a 5 gallon pot or using a 10 gallon pot that's half full - ballast or not; but, if you're using a soil that DOES hold PW, there is a significant advantage to using 5 gallons of ballast and 5 gallons of soil to fill a 10 gallon pot - as long as there is at least 1 continuous column of soil that reaches the bottom of the pot so water doesn't perch above the ballast.

See D in the photo below, and note the reduction in PW volume ballast makes in the second photo.

Al

Pip, I'm not sure whom you're lecturing, about what you're lecturing, or why. You quoted me in your response, but I don't understand your point or how it pertains to me.

Lol well your clearly a liberal, hear something you don't like so claim you don't understand. There is absolutely nothing confusing about what I said. I DONT CARE WHAT YOU DO. I'm letting others know there is a better way, lighter medium.

I suggest you edit your post to remove the political commentary....liberals might not appreciate it. (As an Independent Conservative, I don't really care, of course).

Secondly, there is no evidence that your way is better, nor have you really made a case for whatever confused method you're advancing. The medium that I employ is quite light, being primarily bark and perlite.

Josh

Fascinating! Now there're liberal and conservative ways to fill a pot with growing medium. Great stuff!

+oM

Well, you can use liberal amounts of mix, spending more money, or you can be conservative, and insert spacers, thus saving money...

Good one, Bragu! :-)

Josh