|Lantana's are always a favorite with desert residents because of their low level of maintenance and reliability for color.|
A. Whenever talking irrigation, two important considerations should be made; how much water to apply and how often to apply it. How often refers to which valve or station they are on. How much water refers to the minutes of operation of that station AND the size and number of drip emitters around each plant.
Deeper rooted plants like oleander should be watered less often (but with more water) than shallower rooted plants like lantana and honeysuckle. Ideally, oleander should be on a station (valve) that waters other trees and large shrubs not desert adapted. The lantana and honeysuckle would be fine on the same valve.
Next is size. Larger plants should receive more water spread over a larger area than smaller plants. Some oleanders get quite large while others, petite are dwarf varieties, would do fine with a smaller amount.
Larger oleanders should probably get somewhere around 15 gallons or so each time they are watered. Smaller, petite oleander probably between five and 10 gallons. If using drip irrigation, the size of the drip emitters used (gallons per hour) depends on the minutes allocated for that station.
Lantana needs one or 2 gallons every time it’s watered. The honeysuckle, probably 3 to 4. If watered the same number of minutes, double the number or size of the emitters used on the honeysuckle.