Tucson in the month of May gives us a lot of colorful enjoyment from the flowering trees but also there are unfortunate sights on school playing fields where, for some unknown reason, the mowing crews have lowered the blades and leave the grass very short. This means that the sun dries out the soil and subjects it to high temperatures. This would be avoided by allowing the grass to grow a bit longer. In our vegetable gardens we can, and should, cover the soil with mulch but we can’t do the same for grassed areas. A good way to stop the sun from baking the soil and cooking the roots of our vegetables is to use flakes of alfalfa hay and lay them on the ground as if they were tiles. A flake should be three inches thick in order to be effective. Alfalfa is nitrogen rich and therefore contributes to soil fertility much more than do flakes of straw.
Street trees have been most beautiful this spring and the display of color has been spread over a few weeks so we’ve been able to enjoy a long display. I suspect that warming weather has stimulated flowering where the trees enjoyed some shelter from the cold, and the later flowering took place anyhow. In our vegetable gardens the warming weather has stirred kale and broccoli and chard to “bolt” (in other words, to flower.) That means the end of their growing period. You can avoid “bolting” by methodically removing the lower leaves and this seems to “tell” the plant to continue producing leaves instead of flower stalks. Also a shortage of water seems to remind leafy plants that their life is coming to an end and in order to perpetuate the species some seed making is called for. Use a by-pass pruner to snip the lower leaves close to the stem instead of tearing them off.
If you do the wrong kind of pruning on a street tree you’ll spoil its future growth and shape. In general you want to discourage downward growing branches and favor those that grow upwards, but how you do it is important. After determining which branch you want to take off, follow it back to the main limb and make a close cut that leaves no stub. Those people who merely cut off the ends of a “wild” branch discover that pruning actually stimulates new growth and they are left with a mass of new end growth. This will be very obvious if branches are cut that are rubbing against a wall or roof of a building. Go back to the origin of the branch. The same consideration should be given to reducing the height of a tree that has grown too tall. The operation if called “drop-crotching” instead of “heading back”.
Street trees and power poles do not make good neighbors. You can see the disasters for planting a tree under the power lines. The tree has to be cut to avoid contact and the tree now loses its natural beauty.
Often the wrong kind of tree has been planted along our streets. The prime example is native mesquites instead of the better-shaped Chilean thornless kind that are more upright in growth and more graceful anyway. In the case of fruiting summer vegetables, like tomatoes, bell peppers and eggplant, it’s good to plant varieties which spread their foliage that saves the fruit from being sun scorched. Don’t prune and thin your tomatoes like you did back east–you’ll be sorry. If you haven’t chosen a spreading leafy fruiting kind you’ll get good quality fruit by covering your plants with a light fabric. There’s no need to build a structure–simply let it float over your plants but hold it down with a brick at the corners to stop the wind from blowing it away.