posted 12 years ago
I'm wondering if lack of topsoil could be another factor in the problem. When they build houses, especially if they have basements, they often don't worry about whether they leave topsoil or just subsoil on top in the yard. Without much topsoil you'll wind up with just a few hardy weeds. As Laura said, adding organic matter may be the answer. Between the sun and watering and lack of cover, the top of the soil can get pounded down so the air pockets disappear, making the plants have a really tough time getting their roots to penetrate and also depriving the roots of oxygen. Without organic matter in the soil, few earthworms will be there so there won't be worm tunnels for the roots to follow, and the fungi and bacteria that hold the structure of the soil to maintain air pockets will also be gone or struggling. If your ground is freezing now, the frost crystals can break up the soil and make some air pockets but then if it gets walked on that crushes them back down.
Plants themselves will cool the air as they evaporate water on hot days. So a planted yard will be cooler than a bare dirt yard.
Maybe planting some white clover then putting down a thin layer of straw to give it some shade and hold in soil moisture until it gets established might help. You'd probably have to find an inoculant to help it fix nitrogen. Farmers do "frost planting" with clover, which is putting the seed down in winter so it can grow early in spring. So now could be a good time for that. Clover will help any bushes you plant by fixing nitrogen, can help compete with the spurge you have, and will be attractive and nice to walk on. And it gives you the option of feeding bees. Downside is, if you have chickens they'll eat all the sprouting clover seeds as they find them - what happened to me this year!
I'm also wondering if your dog has much to do with it. The urine can kill plants. The digging for a cool spot to lie down kills, and the walking (on tender newly planted plants) also kills. I've got two dogs and I think they're one of the biggest obstacles to "yardening". Well, other than the chickens. Bored dogs do get through just about any obstacle we try to erect. My sister's dog ate the hoses off of her air conditioner.