Q: We are planting a family vegetable garden. Would a container/raised bed do well in this environment? We’re used to summers in Colorado and are wondering if there are specific tomato, cucumber, pepper, and lettuce varieties that do well here. Will root crops like carrots and radishes do well in containers? The west side of our house gets late afternoon shade from the neighbor’s house, and that is the only space we have. Would this be OK? When is the best time to plant? Soon?
A: I sent you a vegetable growers’ Bible written by Dr. Sylvan Wittwer when he was growing vegetables in Southern Nevada. Anyone interested who wants a copy can ask me for it and I will email it to you. It contains a planting calendar.
He is a traditional gardener and not organic. Substitute organic alternatives if you want to use a different soil, fertilizer or pesticide.
When possible, use older varieties that are known successes until you get the hang of growing vegetables in this climate. When using raised beds, use compact varieties that produce fruit quickly and then throw them out and replant.
Plant cautiously any new varieties. They sound cute. That’s a marketing gimmick. Sometimes they perform well in the desert and sometimes they don’t. Plant new varieties for three years in a row before calling them a desert success.
If planting a viny plant, let the vines sprawl. The roots are important to the plant, not the vines. Keep weeds under control. Weeds breed bugs. Bugs eat plants or spread diseases. Inspect and walk it at least daily.
I like containers. Double pot them so they don’t get so hot when the sun shines on the outer walls. Use 5- to 15-gallon nursery containers and fill them with your favorite soil to within 1 inch of the top rim. Put a 3-inch layer of gravel in the bottom of the outer pot to keep them from lodging.
If you are using tap water, filling these containers within 1 inch of the top will have some water coming out the bottom. This helps remove salts when you irrigate.
Q: Why use a weather app? I have planted tomatoes at the same time every year and they have done well.
A: You were lucky. Sometimes warm-season plants like tomatoes, peppers and eggplant are planted as early as mid-February. Other times the weather stays cold until mid-March. Using a weather app on your phone helps predict the weather one, two or even three weeks ahead.
Warm-season crops like tomatoes prefer growing in warmer air and soil temperatures . Having two raised beds, one in full sun and one in seasonal shade, can add about one month to your growing season.
But there are other tricks you can use as well. Look at your phone’s weather app. Covering the prepared soil with clear plastic a week before the weather starts to warm up helps get an early jump on warm crops like tomatoes.
Q: I want to start up my raised vegetable bed again after two or three years. Can you help?
A: Mix compost into the soil first. You can use steer manure, but it should be done in the fall so it has time to rot. Remove your irrigation and mix a layer of compost into the soil as deep as possible.
If the soil is 10 inches deep in your raised bed, then mix the compost that deep. The soil should be similar from top to bottom to improve drainage.
How much to mix into the soil depends on how much is there. You might mix a quarter-inch layer each year in a well-amended soil. Or you might mix to as much as quarter of its content, and then one annual quarter-inch layer after that if it is raw desert soil.
You can judge how much is present by digging with a hand trowel or checking it visually using its color. For vegetables, the soil should be easy to dig with a trowel when it is moist and dark.
Next is how much fertilizer to add. That depends on how rich the compost was. Some animal-manured composts are rich, while some are not. Most soils are darker after composting and ready to plant as is. Some need a starter fertilizer added. Again, ask your salespeople.
Finally, is the “when and how much” to water. Irrigation is trial by error, but once you have it established, watering seldom changes.
If you are using Las Vegas tap water, then water until the entire soil mix is wet from top to bottom. Watering like that flushes salts in the water out of the soil. This takes around 30 minutes, but it might be more or less depending on your soil and irrigation system.
How often to water depends on the time of year. In the summer, water once before it gets hot. That is usually once a day. Watering only once when it gets hot allows for the roots to get water from top to bottom.
There is a trend to water as often as nine times a day. Be careful. Frequent irrigations promote lots of surface roots and loss of heat tolerance because shallow roots are where the water and dissolved fertilizers are located.
Plants with lots of surface roots are not very tolerant of heat. Instead, use a light application of mulch and irrigate once, during the heat.
Q: Please explain the 40-30-20-10 rule when watering. Why is it important? There are lots of different ways to water plants.
A: Most plants use water stored in the soil following the 40-30-20-10 rule. Divide the roots of plants into four equal parts. If it is a large tree and its roots are 3 feet deep, divide this 3 feet into four equal parts (9 inches for each part). If 1-foot-tall plant roots are 1 foot deep, divide the roots into four equal parts (3 inches for each part).
After heavy rain or full irrigation, plant roots start using the water stored in the top quarter (25 percent) first. When this top layer starts getting used, then the plant begins using the second (25 to 50 percent) layer of stored water, then the third and finally the fourth.
When the plant finishes using water stored in the soil, it uses this water following a 40 percent (top), 30 percent, 20 percent, 10 percent (bottom) rule. Plant roots, just like the top, grow when they use water. This is one reason plant roots grow deeper when they are watered deeper.
Q: In addition to freezer damage, what other differences do tropical plants have from nontropical plants?
A: Tropical plants freeze sooner, which just means they start getting injured at temperatures below 55 degrees. Tropical plants and fruit experience damage starting at much higher temperatures than temperate plants (plants that can tolerate freezing temperatures). Temperate plants experience freezing injury starting at 32 degrees.
Damage to bananas (soft and brown) occurs at higher temperatures, a few hours after putting them in the refrigerator (39 degrees). Even tomatoes are damaged when put into a refrigerator.
Most tropical plants and their fruit are damaged at storage temperatures higher than temperate plants (apples, peaches, strawberries, pomegranate, ash, poplar, mulberry).
Plants, more than animals (which can move from place to place because of their legs) are more sensitive to changes in their environment. They can’t move.
Plant damage due to freezing is the most obvious. But other environmental changes are also important such as the strength of sunlight, wind, water availability and quality, air, and soil changes. Plants don’t like it. They are damaged or dead.
The better we can provide for these damaging environments (garage protection from cold, west side vs. east side of buildings due to light intensity, protection from wind, change in humidity, irrigation and drainage), the better off the plants are.
Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.