Gardening in Tucson
and Southeastern Arizona

Watering

• Drip watering plants is not recommended in hot summer areas. Drip watering causes roots of plants to grow close to the ground surface where they will become baked by the summer sun.
• Instead of drip watering, deep soak every one, two, three or four weeks. This means letting a hose run for 30 minutes to three hours until the ground is soaked to a depth of at least 3 feet. Force an iron or steel rod with a handle into the ground to test the depth that the water has reached.
• The frequency of deep watering depends upon the age of the plant. Plants in the ground less than one year will need weekly watering in the spring, summer and first half of fall. Plants in the ground over three years may need deep watering only once a month during the warm season, and much less in winter. Allow the soil to dry out between soakings so air can get to the roots.
• Watering frequency also varies by species. Some plants go dormant in summer heat and cannot tolerate water during this period. Other plants need more frequent watering in summer months. Check a recommended gardening book describing your plant and its water needs.
• See Planting and Watering Trees for information on trees.

Mulching

• Mulch is placed on top of the soil to keep it moist and insulated from temperature extremes of hot and cold. Mulch may be put down anytime. Clear the area of weeds first, and consider putting down a commercial weed barrier (porous landscape cloth) next to the soil to keep the area weed free. Cover that with mulch.
• Shredded bark, straw, sawdust, composted mulch and aged compost can be used. Compost and composted mulch will add long-term acidity to the soil through rain and watering.
• Make the mulch layer 1" deep. Keep mulch away from the root crown and trunk of the plant to prevent disease and excess moisture on the bark that invites critters to nibble. Deep mulch allows rodents to build nests and hide.
• If the ground is very dry, water the plant deeply before adding mulch.

Solarizing / Sterilizing the Garden Bed

If you had a problem the previous growing season with mites, nematodes, fruitworms, fungal diseases, or weeds, solarizing is a cheap, easy, and environmentally friendly way to sterilize the soil. Using a clear plastic tarp and sunlight, many pests and weed seeds can be killed by high temperature. It will, also, kill earthworms if they cannot burrow deeper into the soil. Obviously, the fewer the clouds, and the higher the sun in the sky, the more effective this technique becomes. Do this two months before planting a new crop.

1. Rake and level the garden bed. Remove any plants, roots and rocks.
2. Water the bed evenly and deeply.
3. Cover the moist garden bed with clear, 1- to 2-mil, plastic tarp. This will help sunlight most fully penetrate the soil. The tarp should extend to the sides where it can be weighed down with a 2x4" frame or rocks. Do not use thicker tarp or black tarp.
4. Let the tarp stay in place for 8 weeks.
5. Covering the first tarp, lying on the soil, with a second tarp 3 inches above it, sealing in a pocket of air, will significantly increase the temperature and extend warming further into evening hours. A 2x4" frame can be used to provide the separation and seal the sides.