What to Grow Under Redwood Trees

giant chain fern (Woodwardia fimbriata)

giant chain fern (Woodwardia fimbriata)

Q. I have 11 coast redwoods in my yard. They are beautiful, BUT it is very difficult to find anything to grow under them.
Between the root system, soil acidity and the shade, my options are limited. Do you have any ideas what I can plant in the ground under them as well as container plants I could put under them?
– Randy Banks, Valencia
A. Coast redwoods (Sequoia sempervirens) are the world’s tallest trees, some select specimens measuring more than 370 feet in height. They grow most rapidly during their first decade of life, capable of reaching up to 60 feet during that time. They grow faster in Northern than in Southern California due to the cool and moist conditions that prevail in their habitat up north. California historians frequently cite the mystique of these trees as a factor, beginning more than a hundred years ago with John Muir’s otherworldly descriptions of them, in drawing easterners to visit and eventually settle in this state.
Your query about what to grow under redwoods raises the general question of landscaping under trees. Some common practices deserve mention. The detrimental practice of planting close to or in contact with tree trunks should be avoided.
When plants encroach on a tree trunk, the crown (where trunk meets soil) stays constantly moist. This may result in crown or root rot, often invisible until the tree suddenly dies. In this context, it is advisable to regulate sprinklers so that water never sprays directly onto tree trunks. To avoid this issue, some gardeners opt for a wide circle of mulch, if not bare ground, under trees, stretching from the trunk to the canopy perimeter line.
I like your idea of container plants under trees, especially if they are hand watered. Not only do you keep water away from the trunks, but you also have the freedom to move your containers around as trees overhead mature and light exposure changes.
One of the best candidates for growing under redwoods is Heuchera, sometimes referred to as coral bells, a ground cover for semi-shade. The outstanding feature of Heucheras is their foliage. The most popular selections have large, ruffled, purple to bronze colored leaves, but there is also a noteworthy lime green cultivar and a gunpowder blue.
You could easily mix and match a dozen or more Heuchera varieties in the shade of your redwoods. One issue to consider with Heucheras is their relatively brief life span, as they seem to disappear within a few years of planting.
Ferns grow well under redwoods. Giant chain fern (Woodwardia imbricata) is cold hardy and grows up to 7feet tall in Northern California, although it will probably not grow more than 4 feet tall in our area.
Lady fern (Athyrium filix-femina) is a tough, cold tolerant ground cover. Many ferns are surprisingly drought tolerant, especially when mulched, and do not require fertilization. Most grow from rhizomes and, when they become shabby, are rejuvenated by being cut back to ground level.
Other plants recommended for growing under redwoods include: Oregon grape (Mahonia species), western bleeding heart (Dicentra formosa), redwood sorrel (Oxalis oregana), manzanita (Arctostaphylos species) and meadow rue (Thalictrum species).
Q. Due to the water restrictions and my pocketbook, I want to be very careful what I buy and plant. How do you know what flowers to plant in which season? Do you plant the flowers you want to bloom in spring in the opposite season? In fall? In winter? More appropriately, what annuals should I be planting now for blooming in the fall?
I get so confused when I go to my local nursery. For example, right now they are selling blue lily of the Nile (Agapanthus africanus), which I know blooms in the spring/summer, and bougainvilleas, which I also know bloom in the summer heat. Can you help?
– Paula Ruiz,
Woodland Hills
A. When it comes to plants purchased in containers for typical garden use, fall is the best time to plant them, regardless of when they bloom. The reason for this is that up to 90 percent of a plant’s root growth takes place in the fall.
The soil is still warm from summer’s heat even while air temperatures cool and the stress of hot weather is removed. In our climate, fall planting is especially important because scorching weather often arrives with the spring, so if you wait until then to plant, conditions for growth may not be optimal.
Your primary concern when planting should be roots. Once the root system is established, plentiful flowers will follow. Try to plant this month or during the first half of November. By Thanksgiving, the probability of freezing temperatures and drenching rains, both of which discourage planting, increase.
That being said, you really can plant in our area from containers at any time of the year, as long as you monitor the weather daily and adjust watering accordingly. If you have just planted tropical species (such as bougainvillea) and freezing weather is forecast, take precautions by wrapping the plants in burlap in the evening and removing it in the morning. You can purchase burlap tarps at lawnmower shops.
Small plants can be protected, from both cold and heat, by caging them in 5- or 15-gallon black plastic nursery containers turned upside down. As for annual flowers, snapdragons, pansies and primroses are reliable fall favorites, as is stock to a lesser extent. Annual cineraria is gorgeous but short-lived. The most robust, if priciest, bloomer is cyclamen. This plant is a perennial, and you can keep it in the garden for a full year, or longer, if you withhold water from it, except to keep the soil barely moist, after it stops blooming.
If you want to save money where annuals are concerned, plant seeds. Growing annual flowers from seed is an acquired skill, but your patience and perseverance will be rewarded. Start with big seeds such as Nasturtium and sweet pea (Lathyrus odoratus). The back of the packet will instruct you as to the best time and depth to plant.

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