Water Rosemary Twice a Month in Hot Weather

rosemary (Rosmarinus officinalis)

rosemary (Rosmarinus officinalis)

Could you please suggest what to plant along my driveway? There is sun all day and everything I plant burns up. The driveway is 20 feet long by 4 feet wide. There is no water supply there so I have to water it by hand. If I go away for 2 weeks in the summer it burns up. Can you help me?
Sonia Draper, Chatsworth
Thank you for a wonderful question that goes to the heart of the challenge faced by water thrifty gardeners throughout Los Angeles. In truth, it is eminently feasible to create intriguing gardens, full of color, fragrance, and attractive to pollinating insects and birds, that do not require water more than once every two weeks.
Based on years of plant watching, I would say that, for full sun exposure, rosemary and bougainvillea are the most reliable selections for planters than cannot be watered more than once every two weeks. Where rosemary is concerned, both upright (Rosmarinus officinalis) and trailing (Rosmarinus officinalis ‘Prostratus’) types, once established, will do fine if they are watered once every two weeks. As for bougainvillea, I would imagine you would want bush type plants for a driveway planter and so I would recommend a wonderful purple species (Bougainvillea spectabilis) with shiny green foliage that may be kept as low as three feet with regular pruning. ‘Raspberry Ice’ would be a naturally bushy alternative, with variegated leaves and red bracts, which will not reach over three feet tall. There is also a bougainvillea shrub variety called ‘Torch Glow’ that has stem hugging bracts. It grows to a height of six feet, does not need staking, and has multiple branches growing from its base. You would need to prune ‘Torch Glow’ regularly to keep it within the confines of your four foot wide planter.
Gazania is another species you might consider. Twenty years ago, gazania was the most popular ground cover for sunny exposures. Ironically, just as people started thinking about water thrifty plants, gazania experienced a decline in popularity. It seemed to simply go out of style. Yet gazania, once established, can easily endure two hot weeks of summer without water. In fact, it usually dies due to overwatering. Native to South Africa, whose Mediterranean climate resembles our own, gazania is accustomed to a long dry season. Rhizomatous blanket flower (Gaillardia spp.), a gazania cousin, is similarly drought resistant. When you first plant either of these ground covers, keep them well-watered. Ideally, you would plant in fall or winter so that roots have a chance to develop several months ahead of summer’s sizzling heat.
If your passion is for pink, you might consider Mexcian evening primrose (Oenothera speciosa), another drought tolerant ground cover. This long blooming selection grows from rhizomes or thick underground stems, in the manner of blanket flower. Both blanket flower and Mexican primrose may easily be propagated either by division of whole plants or by digging up their rhizomes alone and transplanting them to other garden spots.
‘Flower Carpet’ roses are also worthy of consideration for a drought resistant planter. Once established, they are extremely sturdy and more than capable of withstanding two hot summer weeks without water. Aside from red, pink, and white varieties, scarlet, yellow, amber, coral, and apple blossom colors are also available. ‘Flower Carpet’ roses, nearly always in bloom, can easily be kept at a height of three to four feet.
You might also consider a hedge of compact myrtle (Myrtus communis ‘Compacta’) or calamondin (Citrus mitis) for your 4 x 20 foot planter. Compact myrtle has tiny diamond shaped leaves that, when rubbed, emit a delightful fragrance and calamondin is unique among citrus types in bearing fruit throughout the year. You can maintain calamondin as low hedge with regular pruning and you will not have to worry about a freeze since it is hardy down to 20 degrees Fahrenheit.
Certain herbaceous perennials are worthy of consideration for your driveway planter. Herbaceous perennials, which never form wood, grow from bulbs, tubers, or rhizomes and may be cut back to ground level, once flowering is over and foliage has faded. Irises are highly resistant to drought and are rivaled only by orchids for floral display. Society garlic (Tulbaghia violacea) is virtually indestructible and offers mauve flowers in all seasons. Its silver and green variegated version may be more appealing than the traditional solid green.
No discussion of water saving plants would be complete without mention of ornamental sages (Salvia spp.). Many species, both native and imported, can easily exists on water applied once every two weeks. Mexican sage (Salvia leucantha) and Texas sage (Salvia greggii) are the first that come to mind but many other sages, with flowers in pink, red, blue, lavender, and purple, would also be appropriate. As a bonus, sages will bring hummingbirds into your garden bed. And don’t forget a wildflower seed mix, an alternative that will display most of its color in later winter and spring but will be satisfied with a minimum moisture allowance.

Tip of the Week: Creating the proper water saving environment involves more than plant selection. Watering intervals may be extended by maintaining a three inch layer of mulch around plants, especially when they are establishing themselves in the garden bed. Make sure to keep mulch from touching stems and trunks to prevent fungus problems. Once plants have taken over an area, especially if they are low growing ground covers or compact shrubs, their foliage will provide a living mulch for the area, minimizing evaporative water loss from the soil surface, as if a layer of shredded bark had been placed there instead.

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