I face this issue all the time because I use cut down (ht) nursery cans as training pots for bonsai. Since I own a class company, I have unlimited access to screen material, but it's inexpensive & won't break the bank if you want to try this: I cut strips of screen about 2" wide and several inches longer than the pots diameter. I position them so they cover 2 holes each, on opposite sides of the pot. This means the strip runs up the side to cover 1 hole, then across the bottom of the pot and up the opposite side to cover the hole there. I use a thin stick that's flat on the end to hold the screen in place temporarily, and I just place a small pile of soil on the screen to hold it secure while I fix the other 1-2 screens in place in the same manner. The screen strips are reusable if you wish. You can also do the same thing using 1 piece of screen for each hole, but I find the '2 for 1' application easier. AL

I just addressed a group of specialty growers at Matthaei Botanic Gardens in Ann Arbor, MI last Wed. One of the points I made was that you can ALMOST say that the better the aeration and drainage your soil has, the better will be the likelihood of your getting your plants to grow to their genetic potential. I emphasized the 'ALMOST', because there is a balancing act here. If you go too far toward increasing aeration and drainage, you make it less convenient for yourself, because you need to water more. This isn't to say the plants wouldn't love it - they will. It's just that you need to consider not so much balancing water retention and drainage as what you're willing to do for more robust plants. Some will say that MG and other soils are good enough, and that they are able to manage watering so they're satisfied with their results .... and that's perfectly fine. If they're happy, we're all happy, but that doesn't mean they aren't leaving something significant in the way of growth and vitality lying on the table. Some will argue that point, but scientific evidence and practical current convention illustrates otherwise. It's just plain easier, and there is a wider margin for grower error if you're growing in a highly aerated medium. I've been carrying this message for years, here at GW and other forum sites, along with many other messages associated with growing in containers. One of the results is that I'm invited to address groups far less often in other areas (like pruning, propagating, bonsai talks .....) and much more often in areas related to container growing - specifically soil science - how water behaves in soils and its effect on our success/satisfaction. IOW - more and more people who are serious about improving their growing skills are taking note of the fact that aeration and drainage are at least one of the cornerstones, if not the keystone, of our container growing endeavors, and they want to understand that relationship. Like josh mentioned - the peat-based mixes are sold because there is a market for them and a profit to be made. That they're sold doesn't make them the best choice for growing, any more than that an automobile is sold makes it the best way to traverse the country. That sounded clumsy, but the point is valid. ;-) If you're guided by how much aeration a soil has and will hold over the long term (durability), and ensure that it's considerably more than that offered by peat-based mixes, you'll be increasing the likelihood your plants will do well and increasing your margin for error by default. It's not water retention per se that is the limiting factor, it's how the water is distributed in the soil - the perched water is the culprit that is limiting. Do what you can to eliminate the perched water (there are several tricks I've written about) and you'll improve your chances for success. Al

Those temps are bad kms2! I have noticed some of my trees in black pots and gritty mix feel like they are baking! Yes, Plumerias grow in the tropics and it's hot BUT they are in the ground. Their roots are cool. Their heads can take full sun all day long but they like their roots cool. Also in most of the tropics there are breezes that help to keep leaf and temps down. I have grown them both ways for years, there isn't a doubt in my mind, they do better planted in the ground. However, let me say this... if they are young, small trees or rooted cuttings, I suggest leaving them in pots until they get bigger and have a well developed root system if you have to move them inside in the winter. In.South Florida or the Keys, put them in the ground and leave them alone and watch them take off. I have a Lutea that was being a real pain. It's a tall and skinny ugly stick that was that way when it was sent to me and it has never bloomed. After I took it out of the ground last October and wintered it in a pot in the garage, this spring I could not get it to do anything. No claws, then claws, claws would shrivel up. I repotted it in gritty along with all the others. couple of months later, still no leaves. I took it out of the mix, a couple 1" tiny brown roots. I was over it. I stuck it in the ground by some that are in pots and told it to root or die, I didn't care which it did. It sat there doing nothing for a couple of weeks and I waited to see if it rotted. Suddenly it took off, leaves all over the place, which means it also is rooting. I gave it some Root Excelerator to help the roots keep growing. No heat mat needed, The ground provides heat without the stress of wild temp swings which occur in pots. I believe bigger trees need to be in the ground and do far better by planting them in the spring, lifting them in the fall if you must due to freezes. Put them in a pot with the soil they were in while planted, put them in garage, greenhouse, whatever you use and leave them alone until spring. On warm days you can mist or give a cup or so of water, but keep them dry. Each year they will get much bigger than they would in pots. I have white plastic trash bags around some of mine in pots that get morning to early afternoon sun at a brutal angle. The heat of those black pots filled with gritty is insane down here in FL. The white bags reflect the heat and make a huge difference! We have had so much rain, day after day, LOTS of rain. I have about 100 in Al's mix and have yet to have 1 rot. In fact I have never seen such explosive root growth and such healthy roots on potted plumies. They are coming out of the bottom, all over the top, even ones that were just rooted in April have filled 1 gallon pots and are read to move up. Roots seem to love the gritty mix but you do need to get those temps down on the pots or the roots near the pots outer sides fry and turn brown. It's easy to test this. Put one where it gets sun, don't turn it. Take it out in a couple of weeks and check. All the roots on the inside that faces the sun will be in bad shape, the ones on the backside, perfect. Once I discovered this I moved most of them so the angle of the sun wasn't as bad, the others that get that intense angle from 9 Am to 2 pm I wrapped with white plastic to reflect the heat. It works,leave the bags loose so the black pot doesn't show through if the bags are thin. My trees look great, growing well, not many blooms yet. They are recuperating from the moves and repots I imagine. I may get mostly roots and growth this year but that's ok. With healthy plants and a big healthy root system, the booms will come in time. My Kapalua has an inflo. Hopefully all this rain won't cause the buds to drop off.

Hi Rina, Thanks so much for the answers. The containers are tall -- anywhere from 20-35", but I plan to fill the bottom with styrofoam. I already have one planter under the covered entry area and I filled it about halfway with styrofoam, then covered that with bug screen to hold the gritty mix in place and keep it from shifting down in the crevices. That has worked really well, so I'll probably do the same with these. I'm attaching a photo of what they should look like. The farthest 3 to the left are approximately the sizes I'll have, except the shortest one will be taller. I will have 2 of each size, so 6 in all... so you can see that I will wind up needing a good bit of soil (well, gritty mix). And speaking of the container depth, is there a rule of thumb when it comes to depth of soil in containers and cacti? Thanks again for the help!