Originally Published: May 7, 2005 5 a.m.
OK, I'll admit it. This is an unusual spring for the tri-city area. I just can't get used to all the rain this spring. By this time of year we are usually in a warming pattern that increases through July until the monsoons arrive. At least I am able to wear my shorts most days, but the nights are chilly.
I think this is it for the cool nights. In looking at the long-range weather forecast, we should be all right to plant the garden. That includes the warm season vegetables, annual flowers that love the summer heat, and herbs such as basil and coriander. It all hinges on the night-time temperatures. What you are looking for are night-time temperatures around the upper 40s. I have had geraniums planted in containers for two weeks now, and they look great. They do, however, have a little protection from an overhang at the front door.
If you can't get to planting those tomatoes right away, you have plenty of time. I usually don't get to mine until the first of June. Gardeners get so anxious that they sometimes jump the gun and plant before the soil is warm enough.
Thrip are in epidemic proportions this year; I've never seen them this bad. Thrip love moist, cool spring days.
This is the perfect spring for huge populations. I was sipping coffee with Lisa, my wife, this week on our back deck, and they were so thick I found specks of insects in the coffee cup É Yuck!
Thrip are also called "no-see-ums." They are like tiny white specks floating on the wind. Symptoms on your plants will be curled leaves with possible black tips. Flowers will wither quickly and often have a scorched look, as if someone had taken a blow touch to them. You won't see the bug with the naked eye. The best way to spot a problem is to take a white sheet of paper to the plant and tap a branch over the paper. If you see specks of dust hopping around the paper, you have thrip eating your plant.
The best solution is an organic oil made from the Neem tree in Africa. You are looking for a product with Neem oil in it. At my garden center it's called Triple Action Plus. Neem oil also has a repelling action to it as well. Bugs don't like the taste of plants that have been sprayed with Triple Action Plus. I recommend this spray to all gardeners as a first line of defense in bug killers.
Watering systems have been on for a month now. Be careful not to water too much. I see more cases of over-watering at my garden center than from under-watering, especially this time of year. It is possible to drown plants in clay or rocky soil. If we have close to one inch of rain, turn the irrigation system off for that week.
Proper watering is the hardest part of growing plants. Be careful of garden professionals who claim to know exactly how you should water. Each yard is different. My house in Prescott Valley needed different watering in the front yard than in the back yard. That's mountain soils for you. Soil bands change with any grade change and caliche can show up anywhere.
If your plant shows signs of over-watering stress, check the soil moisture 2 inches down before watering. You must work with nature to keep your plants healthy. The problem with over-watering stress is it looks just like drought stress. People tend to pour the water on even more, ensuring the death of the plant.
Under-watered plants have roots that dry up and wither, leaving your plant with a smaller root structure. Over-watered plants have roots that have rotted off, leaving your plant with a smaller root structure. The symptoms on the top growth are the same. The only way to be sure is to use a moisture meter or dig a small test hole and visually inspect the soil.
When you water, think like it is June. It's hot, it's windy, and plants need a lot of water each week. Leave the system running a long time each watering. The question is frequency. How often should I water per week, or per month? On average, established trees and shrubs need watering once a week.
How much water should you put on? Think plant root size. Water a small 1 gallon size plant with 1 gallon of water. Water a traditional 5 gallon plant with 5 gallons of water. Water a 24-inch box tree with 24 gallons of water. This is a rough gauge, but it gets you close.
If you are installing new plants this year, you need to supplement the irrigation system with hand watering with the hose once a week until the surrounding soil is saturated. This will take about four weeks to accomplish. In summer it could be longer.
Let's cover winter watering while we're at it. We do need to water through the winter months, December through March. This is hard to believe for most Midwestern folks. Watering for established plants should be once a month. Again think summer water amounts, but the frequency is less. Plants less than one year old should be watered twice a month.
Move the irrigation system as plants grow, and pull the plastic back to encourage root growth. You should focus on the drip line of the plant. That is the outermost branch structure. The roots that pull food and water from the soil are out at the edge of the drip line. Anchor roots are close to the trunk and are only able to keep the plant upright. Plastic too close to the trunk? Use a pitchfork to put holes in the plastic to enable water and fertilizer to get to the outer roots.
People new to the area over-water lawns and flower beds as well. The goal again is to force the plant to go as long as possible without additional watering. This creates a hardier plant with deeper root structures. If the lawn changes color or doesn't spring back quickly when walked upon, it is time to water. I'm guessing once a week right now, twice a week in the heat of summer. See if you can train your lawn to go this long without water.
Humic acid spread around the root zone makes a huge difference in plant hardiness and promotes deeper roots. Again, at my garden center it's under the label called "Soil Activator". Spread on the surface of the soil and water, it encourages new root growth. It is especially effective with lawns and flowers beds. I would use it on any plant that is showing signs of old drought stress, bark beetle or tip borer damage.
If you need diagrams or charts on proper watering, head to your local garden center. I have a really good one that I got from a buddy in Flagstaff. It's not original, but simple and easy to understand. Other garden centers have a version of their own; just ask them for it.
Until next week, I'll see you in the garden center.
Ken Lain is the owner of Watters Home and Garden Center and is an Arizona Certified Nursery Professional and Master Gardener.