Cryptomeria japonica ‘Little Diamond’ is one of our favorite dwarf Japanese cedar selections, this one from Holland Konjin Nursery prior to 1990. This specimen at JLBG is five years old and measures 2′ tall x 3′ wide. At maturity, we have seen these reach 4′ tall x 8′ wide.
How well does this do in the heat? I’m in Shreveport and have tried several times with these dense selections and they turn brown. This is in part shade well drained but not dry soil.
How odd. The compact forms are commercially grown in regions of Louisiana much further south, so heat wouldn’t be the issue. I’d consider providing a bit more sun. Too little sun would weaken the plant, but it wouldn’t kill it. I’d also look at soil moisture. Soil that is too dry and too wet produces the same results…dead brown foliage. Voles could also be the culprit. When you’re plant dies, you can tell quite a bit by promptly removing it out of the ground. If it comes out with no roots, you either have voles, or the soil is much too wet and the roots rotted…you would see signs of slimy rotten roots. If it pulls out of the ground without the roots having rooted into the native soil, it dried out before it got established. If it pulls out with roots firmly into the native soil, the soil could have become too wet after establishment, or there is something toxic in the ground, or a foliar disease took it out. This isn’t all encompassing, but they are the most likely culprits.