Answer: Since you'll only be gone for a week, you can move your plants to a shady location and water them well. When you return, gradually expose the plants to more and more sunlight each day until they're back in full sunshine all day. Then put them back in their normal places on the deck.
If you can't move the plants to a protected location, water them well and then put a temporary drip system in place by filling plastic liter bottles or gallon milk jugs with water and upturning one in each planter, making sure the neck and opening are buried in the soil. Pierce a hole in the top to allow air to enter (actually the bottom, but since it's upturned, the bottom becomes the top and vice-versa). As the soil begins to dry out water will be drawn from the bottle into the soil.
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