Answer: It's not how many gallons of water you apply to your plants, but how deep and wide the water penetrates in your particular soil. The water should penetrate at least one foot deep for your newly transplanted sage so it soaks the entire root zone. And, the water should go out as wide as the plant is, where the "feeder" roots are taking up water and nutrients. When your plant has been in the ground about a year, you will want to water to a depth of about 2 feet. (The general guideline is annuals: 1 foot; shrubs: 2 feet; trees: 3 feet.) Use a soil probe (any long, pointed piece of metal or wood to poke into the soil) to check how far water has penetrated. The probe moves easily through moist soil, but stops when it hits hard dry soil. Exactly how much to apply will depend on your soil type. Sandy soil drains well but dries out faster; clay soil retains water longer. Since you planted them relatively recently and they didn't have much time to establish root systems before the heat hit (we didn't have much of a spring, May was so hot), I'd suggest keeping the soil somewhat moist for the next month or so, gradually tapering off to allow the top few inches of soil to dry out before watering. Put a 3 inch layer of mulch around the plants to help retain soil moisture and reduce soil temperatures. As for the yellow leaves, they can be caused by many things, including transplant shock. A few yellow leaves is not a cause for concern. I would not recommend fertilizing as that is too stressful in this heat. If you want to fertilize, wait until mid-March of so of next year just as new growth starts. If the plants seems to worsen, send another email to the Q&A site describing where on the plant the leaves are (old or new) and whether they are all yellow or have green veins. Mexican Bush Sage is one of my favorites--I hope this info helps!
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