Mexican petunia

Ruellia brittoniana

Description

The Mexican petunia is a low mounding perennial with long dark evergreen leaves and purple-blue flowers that cover the plant from spring into summer. This species grows 12-15 in. high and to 24 in. wide with a compact habit. One popular cultivar, R. b. ‘Katie’, is smaller with a mature size 12-15 in. in height and 15-18 in. wide. These plants are valued for their attractive foliage and large purple petunia-like flowers.

This southwestern native grows best with regular water and protections from hot sun exposures. It is cold tolerant, surviving temperatures below 20°F, and maintains good foliage character throughout the year.

Plant Type: Perennial
Foliage Character: Evergreen
Habit: Mounding, Compact
Growth Rate: Moderate
Foliage Color: Dark green
Flower Color: Purple
Flower Season: Summer, Spring
Soil Adaptations: Well-draining soil, Sand, Clay
Exposure Adaptations: Morning sun, Heat, Frost, Partial sun
Function: Rock gardens, Hummingbird plant, Flowering accent plant, Container plant, Small spaces, Borders
Height: 12 in. – 15 in.
Width: 24 in.

Watering Schedule: Medium

For most situations, we recommend watering once per week after establishment, watering very deeply in summer, less deeply in fall and spring, and even less in winter.

See our recommendations for how much water to apply each time you water, below. Note that these recommendations are intended for inland valley areas of Southern California including the Inland Empire, San Gabriel, and San Fernando Valleys. People in cooler or warmer areas may use this as a baseline but should adjust based on local needs.

Learn how to provide 1” of water to your landscape here, and adjust to provide more or less based on the recommendations above for each time of year.

Seasonal Watering Recommendations

June – August: once per week, water deeply, applying approximately 1.25” of irrigation.
September – October: once per week, water deeply, applying approximately 0.75” of irrigation.
November – February: once per week, water deeply, applying approximately 0.5” of irrigation.
March-May: once per week, water deeply, applying approximately 0.75” of irrigation.

Learn how to provide 1” of water to your landscape here, and adjust to provide more or less based on the recommendations above for each time of year.

Adjusting to your local needs

These recommendations for Medium / Moderate water demanding plants were created for Southern California inland valley areas. Southern California areas closer to the coast and along the coast will usually be able to water significantly less during the warm months of the year. For desert areas, check with local experts to be sure plants are appropriate for the area and anticipate needing to water more.

As a very general baseline, people in Los Angeles and similar areas can try setting a schedule of 80% of the in Spring, Summer, and Fall and adjust as necessary based on observation. The difference is less pronounced in the winter months, so we recommend starting with the same recommendations as above for winter. People in cooler coastal areas such as Santa Monica can try using this same approach but adjust to use 75% of the chart recommended minutes for the Spring, Summer, and Fall months.

Important Notes

These are general guidelines. Always observe and adjust as necessary for your landscape.
If it rains over 1” you will likely not need to water for at least another week, possibly longer. Before watering again, check the soil. It should be significantly dry at least 4” below the soil surface before watering again.
It is important to group plants with the same water needs together in the landscape to avoid needing to over or under water plants when running your irrigation system.
“Smart timers” or weather sensitive irrigation controllers such as Rachio and Hunter Hydrawise are ideal for watering plants in this category because they will automatically adjust how much they water based on the weather so you do not need to reprogram the timer seasonally. Rebates for these types of irrigation controllers are available through socalwatersmart.com.

Mexican petunia

Description

Watering Schedule: Medium

Seasonal Watering Recommendations

Adjusting to your local needs

Important Notes

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Mexican petunia

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