Flowering Freeway median plants in California
Question from Laura:
A relative driving north from Sacramento toward Reading called me, an Ohio Master Gardener, to ask if I knew what shrub might be planted in the median of U.S. 5 for many, many miles. I don’t. There are several hues, apparently: possibly pink, red, white, maybe purple. Can you enlighten us? If you have an answer, thank you.
Answer from Pat:
I have not recently driven the road between Reading and Sacramento. However, here are some of the plants that have been introduced recently for highway planting and are often used for freeway median planting by Cal Trans:
Meilland disease-resistant and pest-resistant rose shrubs developed in France especially for highways include ‘Fire’ (red), ‘Ice’ (white), ‘Magic’ (hot pink), and ‘Pink’ (pastel pink). My guess is these are what your relative saw since I’ve seen them also and found them eye-catching. We are seeing ever more of these roses on highways and it’s a bit of a surprise since one doesn’t think of roses as being an easy plant and we also know roses need regular water. It turns out, however, that these varieties are easy to grow, don’t require a lot of special care, and are especially colorful and pleasing when ornamenting medians and banks on crowded highways near or in cities where large numbers of motorists can enjoy the sight.
Also often planted along freeways, especially in the Bay Area, is bright or deep royal blue plumbago auriculata. (I would guess the variety they are using is one of the improved varieties, like ‘Royal Cape’ or ‘Imperial Blue’. ) Plumbago blooms its head off for most of the year and is drought-resistant once established. I have noticed these plants near to towns and especially in the Bay Area. This is a tender plant that cannot be grown in Ohio unless it be in a house, conservatory or greenhouse.
For many years in warmer zones one has seen many miles of oleander (Nerium oleander) blooming for many months in freeway medians in warm zones but winter frost can hit it up north. Also there is a pest called the glassy-winged sharpshooter that has caused a lot of problems with oleanders. All parts of oleander are poisonous but that doesn’t matter in a median plant and its height (6 feet) and fragrance together with dense foliage of long green pointed leaves, make it a good, drought-resistant barrier plant. Special machines are used to hedge it after bloom. Oleander flowers massively spring through fall in shades of pink, white, and red.
Additionally, native plants such as blue California lilac (Ceonothus) are planted in some areas. In inland areas that get very hot and dry, Texas ranger (Leucophyllum frutescens) is one of the best and toughest plants. It provides long bloom on attractive grayish foliage in hot, dry, desert-like conditions and it’s hardy down to 12 degrees Fahrenheit. Another purple plant one often sees along highways is Lantana montevidensis. This also has lavender or purple flowers and is long blooming, drought-resistant, carefree, and easy to grow, but a hard frost will damage it.