Regular cement is an enormous energy user to produce. To make cement it requires more energy to make it than steel. Wood by far produces less carbon to produce. You also promoting an industry that is a renewable. Trees are replanted here in the Pacific Northwest after harvest. Trees absorb carbon dioxide and store it. The trick is to use the wood material wisely. Building a container without a liner is like wasting 30 to 40 years of tree growth. One could use roofing cement (tar made from petroleum distillation), but as previous stated it leaches unwanted chemicals in the soil, there are some that are made from other materials, but these are not easy to apply. Wood is by far the cheapest used material; though, It is apparent that big box stores and many smaller identities are only concerned in making profits. They certainly do not care about the environment, this goes onward down to the consumer.... they all want the cheapest Chinese made items just so they can have the highest profit margins and lowest price. Most consumers are purchasing to keep up with Joe Schmoe or the Jones' family. These products are built with basically slave waged labor and packed flat boxes, shipped thousand of miles ( even in many cases the wood, logs are shipped thousand of miles producing tons of carbon to transport), last they are packed with inadequate/substandard fasteners- You might as well throw these planters away for these planters will make it only through one or two growing season... We must treat the environment wisely, if we are going to survive. We must buy things that have utility/longevity, buy less than more, buy things that have the least carbon using foot print and buy things we absolutely need.

erlyberd - I started a few about 5 weeks ago. Those are my test plants, and the biggest one is only about 6 inches tall. But they've been under very weak lights, and I've only just started putting them outside. So I can't really predict how big my other plants will get from those. I started planting the rest on April 13. These are going outside right after they sprout, whenever the weather seems ok. I just got done putting the rest of my seeds in damp coffee filters, so I could get them started before the full moon. Now I have to finish putting them in blocks, before they all start germinating, and I have a big mess of tangled roots. I think my plants will be a lot shorter than yours, while still in the tunnel. By the time most of mine are 6 weeks old, I should be able to start transplanting. But some will probably be stuck in the tunnel past 6 weeks, so those could start getting too big. I'm hoping I can get by with a 22"-23" height for most of them, so I won't have to buy more plastic. Then deal with the rest later, if they start getting too big.

A "few hours a day" is not "plenty of sun" by the standards of many cacti/succulents. People frequently make the mistaken assumption that because the light seems bright to their eyes that it must be bright by plant standards. As others have noted, your plants growth is saying otherwise. Just remember to harden it off gradually to much stronger --preferably outdoors-- lighting ....not unlike how a fair-skinned person needs to gradually expose themselves to strong sunlight after long cold winter if they wish to avoid serious sunburn.

Hey KEN, thanks for your insights. Those R4 steel shelves are 41" high and about 36" wide, weight 36 lbs., so it seems very stable. They are about the same height as the top of the railing. I also intend to velcro-strap the uprights of the shelving units to the railing, so it won't be going anywhere. The fabric grow pots I chose have handles on each side. I'm thinking I could bungee cord through the handles and around the wires forming the shelf to anchor the top shelf's plants. There is like 15" between the middle shelf and the top shelf, leaving ample room to get in there to water, remove bad leaves, etc. And there is 17" between the bottom and middle shelves, leaving plenty of room between the middle shelf and the top of the bottom shelf's plants. I spoke with the leasing manager today, to confirm my calculations about the actual working space within the balcony railings, which turns out to be about 6'. I'll have to put one shelving unit on the eastern narrow end and and one in the corner of the front railing. While speaking to the leasing manager, I found out that we are allowed to hang plants from the railing as well. So cool! So that's where I can add in some annuals for a bit of color pop. She also confirmed that lots of people grow lots of different kinds of plants on the balconies, and that my apartment is located on the side which gets more sun on the balconies. I will box up all the hostas & heuchies the day before I move and head out the the Greyhound station on Long Island. They have a Greyhound Express package service which is actually very reasonable. I can ship the boxes of plants and have them delivered to my door in about 3 days. Perfect!