Alkaline soils and western desert soils need help in order for your garden to grow well. You can't pop your plants and seeds into the ground and expect them to do much if you don't render assistance. So, if your veggies and/or flowers have been up and going for a few weeks and are not showing much sign of growth, or worse still, they are becoming lighter green or even yellowish, they are likely crying for nitrogen. Sprinkle a little nitrogen fertilizer (or blood meal or cotton seed meal if you're into organic) around the base of each plant -- as Gordon Wells puts it, "Like you were salting a steak." Then scratch it gently into the soil and water it in. (I have both a hand tool that looks like a claw and a long tool with a claw for specifically that purpose. ) I use blood meal on my veggies, and it provides both iron and nitrogen.
You should see a tremendous difference in your plants within a few days. Most plants will need this periodic nitrogen treatment -- EXCEPT tomatoes -- at least once. (Only put nitrogen on tomatoes once, at the beginning of the growing season, otherwise you will get loads of lush green and few tomatoes.) I do this if the plants seem to need it, even if I have added all those Gordon Wells recommended fertilizer items at the beginning of the season. Make sure to go light on the nitrogen, though, as you could burn your plant, and rinse off the leaves of the plants afterward. Just keep an eye on the progress of the plant and look for lack of growth and light-colored leaves and you'll know it's time to fertilize.
What else do the veggies need?
In my garden, I use fish emulsion fertilizer about three times during the summer, especially when a plant begins to bloom. I buy it at garden centers (like Olson's or Carpenter Seed) in quart or gallon jugs and mix it with water in a 5-gallon bucket. The stuff stinks to high heaven, after all it is a by-product of fish processing plants, but my veggies love it! If veggies can look happy, they do, as their leaves look lush and perky. I put on long sleeves and rubber gloves and plan on a bath right afterwards. (It's a good time to also spray that stinky Liquid Fence stuff that keeps the deer away from your flowers and shrubs.)
My method of application is to, first, apply when the soil is dry so the plants will soak up the maximum fertilizer. Mix the fertilizer well with the water (a sprayer on the end of the hose does this well or, alternatively, a long stick.) Get a pitcher or cut off milk jug (cut off some of the top, but keep the handle) full of the fertilizer/ water mixture and go from plant to plant, pouring a little pool of solution at the base of each plant -- it won't burn plants if you get some on the leaves. By the time you've gone five or six plants, the first liquid will have soaked into the soil. So, go back and water all those plants again with the solution, starting with the first plant. I usually water each plant 3-4 times with the solution, systematically working my garden in rows. It's not a fun process, I admit it, but even complaining kids can help with this process and make it a lot quicker -- just ask my daughters how much they like helping with this. :) The key is really to cover yourself well, as the smell will soak into your skin a bit if you go out there with uncovered arms and hands.
I give much credit to the fish emultion fertilizer for my good yields each year, as I didn't get anything near the harvest I do now before I started using the fish fertilizer. It gives the plants a lot of trace minerals and other needed nutrition. After all, didn't the pilgrims get a good harvest when the Native Americans buried a fish with kernals of corn?
Yellowing can also be a lack of iron or even copper, but usually nitrogen is the culprit with vegetables in the semi-arid desert regions.
What about trees and shrubs?
If you live with alkaline soils and the leaves of your trees and shrubs are yellow and show signs of burning (brown) on the edges, despite regular watering, it means your plants likely have iron chlorosis. This will not kill your trees and it can be fixed.
When faced with my tree leaves looking yellow and burnt, I followed the advice of Larry Sagers, of the KSL Greenhouse Show on KSL radio. In late winter, say February or March, but definitely before the leaves on the trees and shrubs bud out, fertilize them with an iron chelate, pouring it around the soil beneath the trees and shrubs. He mentioned several brands, and I use one, Millers FeriPlus Iron, which is a powder you mix with water. I mix it up in milk jugs and pour it on the soil while there is still snow on the ground -- this will stain, so wear old clothing. The remaining snows and rain will carry the iron into the soil. I do this every winter, and my tree and shrub leaves look great now. Unfortunately, you can do nothing about this problem right now if your leaves show the signs this summer. Mark your calendar for late next winter so you'll remember and do it every year. This year, I applied considerably less than the label asked for, and the leaves still turned out great.
