The Q&A Archives: Salvia Greggii

Question: I am new to this Southwestern desert region having lived in Hawaii for the last 17 years. This region is most likely your expertise. I have several new Salvia's in my rock garden. Not knowing what normally happens to them in winter, one has turned dry, only a couple of small red blossoms left. It's in full sun during the day and planted in the sand we have around the flagstone. The others are green and continue flowering and get more shade. I am only using a drip system for watering 3 minutes a day now since the weather has gotten cooler. Do you think I have lost this one plant?

Answer: You may have lost your salvia, but you might want to give it a second chance by pruning it back to almost ground level. If the roots are still alive it will green up in the spring; if not, you can replace it. Salvia greggii prefers some shade in the hottest desert climates so exposure to too much sunshine may have stressed it out. Watering is a real challenge in the desert and knowing when and how much water to apply becomes easier as you observe your plants over several growing seasons. Here are a few tips:

Desert soil and water both contain salts, which can accumulate in the root zone over time. This salt buildup forms where the water stops penetrating. Short periods of watering cause salts to build up in the top layers of soil and can damage or kill your plant. Salt burn shows up as yellowing, browning along leaf edges, and leaf drop. Deep watering?or leaching?prevents this by flushing the salts past the root zone. Always water slowly, deeply and as infrequently as possible. This is true for any plant. It's important that water always soak deeply through the entire root system. Use the 1-2-3 Rule as an easy method to figure out how much water to apply. Small plants with shallow root systems, such as perennials, veggies, herbs, cacti, succulents have roots that reach about 1 foot deep, so water needs to penetrate that far. When the top 1 inch of soil dries out, it's usually time to water again. Shrubs have root systems that are 2 feet deep so water needs to soak 2 feet deep. When the top 2 inches of soil dries out, it's time to water. Trees are 3 feet, etc. As plants establish root systems, the time between waterings can be lengthened, but it is always essential to water to the same depth. So you are applying the same amount of water with each irrigation regardless of the time of year, but the frequency changes. As warm weather arrives, you need to water more frequently than during winter. A soil probe will help you determine how far water has soaked. It moves easily through wet soil but stops when it hits hard soil. I?d suggest you let your drip run for 30 minutes or 1 hour, then wait an hour or so (for the water to continue penetrating), then use a sharp stick or pointy thing as a soil probe to determine how far the water penetrated in your soil. For most areas, it's necessary to run irrigation much longer than people would think. The majority of the plant problems we see are because drip isn't running long enough. In improved soil garden beds, such as for veggies, it will soak more readily through the soil than it will in landscape settings. Here are some watering guidelines for establishing desert-adapted plants from Desert Landscaping for Beginners, published by Arizona Master Gardener Press. Weeks Since Planting 1-2, water every 1-2 days; Weeks 3-4, water every 3-4 days; weeks 5-6, water every 4-6 days; weeks 7-8, water every 7 days. Gradually extend the watering as plants establish. Note these are guidelines, which will vary depending on your soil type, microclimate, etc. and they apply to desert-adapted plants. As plants mature, emitters must be moved outward to keep pace with the expanding root system. Feeder roots that absorb water are spreading out past the dripline (canopy edge), so apply water just beyond that. Add a layer of organic mulch around the base to help maintain moisture and reduce soil temperatures. I hope this info helps!

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