Agave: Another of Mexico’s Gifts to Gardeners

A recent column provided an overview of the genus Echeveria, called “Mexico’s Gift to Gardeners.” Today, we take a look at the genus Agave, another of Mexico’s gifts to gardeners, with value for larger settings.

Agave species grow naturally through the southwestern United States, Mexico and Central America, Columbia and Venezuela in South America, and the Caribbean islands.

All Agaves are monocarpic, i.e., they die after flowering. Unlike many annual plants, Agaves can grow for several seasons before flowering, setting seed and dying. For this reason have been called “multiannual.” They have also been called Century Plants, but they flower and set seed in much shorter periods, generally when conditions are right to support propagation.

There are two basic vegetative types of Agaves. One type produces offsets (called pups or babies) either in the leaf axils or through underground stems. The other type, called the solitary Agaves, propagates only by producing seeds.

These types are important for placement in the landscape. An offsetting type Agave needs ample space to allow for full development of a larger cluster of plants, while a solitary type Agave needs only enough space to accommodate its mature size.

Agaves generally consist of leaves arranged in a spiral, forming a rosette. The leaves might be thick or thin, succulent or fibrous. Some Agaves have smooth leaf edges, while others have sharp teeth along both sides of the leaf. Some species have leaves with terminal spines, which might be stout and quite sharp.

The rosettes come in several size categories, depending on the species. The smallest can be three inches tall and four inches across, and the largest can be ten feet tall and twelve feet across. Likewise, the flower stalks vary in several characteristics, including height that in some species, e.g., A. americana, can reach up to thirty feet.

There are over 200 species of Agaves. Of these, about 80 are found in gardens, and only about ten species are commonly grown. The typical home gardener in the Monterey Bay area will be familiar with three or four species.

Agave americana, which grows to large dramatic form, is widely cultivated worldwide for its ornamental value. The rosette of A. americana can spread to six-to-ten feet in diameter, and its flower stalk, as noted above, can reach thirty feet. At east six cultivars are available, with different patterns of white or yellow striping on the green leaves.

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Agave americana ‘Marginata’

Agave attenuata gets its specific name from the leaves that shrink to a point. This plant has an unusually curved stem, which is revealed as leaves age and fall off. It develops a rosette of six-to-eight feet in diameter, and produces a flower stalk up to ten feet long. The stalk typically will reflex towards the ground, then arch upward again. This growth pattern gives the plant the common names, the Fox Tail Agave or Lion’s Tail Agave or Swan’s Neck Agave. Because this plant lacks teeth along the leaf margins, or terminal spines, it presents no hazards in the garden.

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Agave attenuata Credit: Annie’s Annuals

Agave tequilana, the Blue Agave, produces large amounts of sugars, mostly fructose, in the core of the plant, making it particularly suitable for preparing Mexico’s well-known tequila and other alcoholic beverages. This plant can grow to over seven feet tall, and produce a stalk up to sixteen feet high. A. tequilana has as much landscape value as other Agave species, but is most widely grown commercially.

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Agave tequilana (Blue Agave)

 

Agave victoriae-reginae, known as Queen Victoria Agave, is a smaller plant, growing slowly to 12 inches tall and 18 inches wide. It is popular as an ornamental for its streaks of white on sculptured geometrical deep green leaves. The leaves lack marginal teeth, and sometimes have short terminal spines. The flower stalk, which can reach up to fifteen feet, displays reddish-purple flowers. This is the only solitary type agave of the species listed here.

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Agave victoria-reginae

Agaves are drought-tolerant, easily grown plants that can bring dramatic architectural forms to the landscape.

Million Pollinator Garden Challenge

We are in the midst of National Pollinator Week (June 15–21)! An unprecedented group of twenty-four conservation and gardening organizations has formed the National Pollinator Garden Network and, with First Lady Michelle Obama, launched the Million Pollinator Garden Challenge.

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The Network challenges the nation’s gardeners to create one million additional pollinator gardens by the end of 2016.

This campaign encourages home gardeners to help reverse the decline of honeybees and native bees, butterflies, hummingbirds and other pollinators. This extraordinary initiative underlines the importance of pollinators to our food supply and invites home gardeners to take effective personal action even as the nation’s Pollinator Task Force mobilizes more than fifteen federal agencies to improve pollinator health.

In a recent column, we urged keeping your garden free of synthetic chemical pesticides and herbicides, and using less-toxic alternatives. The Pollinator Partnership (www.pollinator.org), a member of the new Network, offers specific advice:

  1. Plant for Pollinators (the website includes a link to a cellphone app that lists 1,000 pollinator friendly plants native to the United States)
  2. Reduce or eliminate the impact of pesticides.
  3. Register as a SHARE site (see more about this below)
  4. Reach out to others – inform and inspire
  5. Buy local and organic produce, including honey
  6. Conserve all of our resources; use less and reduce your impact.
  7. Support the work of groups promoting science based, practical efforts for pollinators

The Network concurs with these recommendations, as expected, and adds these complementary ideas:

  1. Provide a water source
  2. Situate your garden and/or plants in a sunny area with wind breaks
  3. Create large “pollinator targets” of native or non-invasive plants
  4. Establish continuous blooms throughout the growing season

Once you establish your pollinator habitat garden, visit share.pollinator.org/ to register your garden on the Pollinator Partnership’s SHARE site. Adding your garden to the site’s map of the United States gives you personal bragging rights as a friend to pollinators and supports the effort to encourage others to participate in the Million Pollinator Garden Challenge.

The website for the Challenge (http://millionpollinatorgardens.org/) provides links to each of its members, and most (or all) of these groups identify pollinator-friendly plants.

Still, because gardening is specific to location, Monterey Bay area gardeners should focus on plants to native to the local region. To find such plants, visit these websites:

California Native Plant Society 

Las Pilates Nursery

Xerces Society

Join the Million Pollinator Garden Challenge. The bees and other pollinators will thank you, and your garden will be richer for the effort.

Rain Gardens – Advanced Water Conservation

Most gardeners have learned that large percentages of residential water usage occur outdoors, mostly as a result of irrigating lawn grass and other plants, and have adopted water-saving practices: replacing thirsty lawn grass with naturally drought resistant perennial plants, especially California native plants, using efficient drip irrigation, and mulch. These strategies involve relatively low expense, depending on implementation.

Some gardeners have gone to the next stage of water conservation, which includes water catchment and grey water recycling. These strategies require equipment, and its installation, both of which could lead to some initial expenses. A 5,000-gallon water tank, for example, would be a substantial investment, but one pays off through long-term water savings or even fire protection.

Today’s column introduces percolation ponds as another stage of water conservation.

When we are fortunate enough to have rain, much of the water from roofs and paved areas runs to storm drains, which in the Monterey Bay area lead eventually to the sea. An efficient storm drain system avoids flooding, but often delivers pollutants into the ocean. A better approach is to direct the runoff to the soil, which filters the pollutants and leads the water into the aquifer.

This approach involves the development of a percolation pond, which is simply a low area that collects and holds runoff so that it percolates into the ground.

The principal objectives for percolation ponds are to filter runoff to minimize pollution, recharge local groundwater, and conserve water.

To include a percolation pond in your garden, find a naturally occurring low area (or create one) that is at least ten feet away from your home and any existing septic field. This separation is needed to avoid having water migrate towards your foundation, or to interfere with any utilities close to the house.

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A rain garden by a driveway in Pacific Grove. Credit Dona Johnsen Landscape Archietcture

 

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A rain garden away from the (east coast?) residence. Credit: EPA:gov

 

The percolation pond should have good drainage, so that it holds water for no more than forty-eight hours. A retention pond, by contrast, holds water for longer periods, and could be designed as a water garden or bog garden.

Determine the surface area of the percolation pond to reflect the surface area of the capture area and the soil type. For example, multiple the surface area of your roof by 20% for sandy soil, 33& for loamy soil, and 45-60% for clayey soil. If you are creating a percolation pond, the bottom layer ideally should consist of about 60% sand, 20% compost and 20% topsoil. This composition would provide effective filtering of the runoff.

Then, adjust downspouts or a sump pump outlet to direct the water into the percolation pond. Depending on the situation, a bioswale could be used to direct the runoff to the percolation pond. A bioswale is a drainage course with gently sloped sides (less than six percent) and filled with vegetation, compost and/or riprap.

In areas that receive regular rainfall, the upper layer of the percolation pond can be planted with deep-rooted perennials, which can flourish under occasional deep soaking, followed by relatively dry periods. These features are called “rain gardens.”

In California, where we need to protect and restore our aquifers, and have current drought conditions, the upper layer might emphasize decorative stones, which can slow the flow of water that might otherwise overflow, and promote percolation. California native plants, once established, would do well in a percolation pond, and also provide both an attractive appearance and environmental benefits. Continue reading

GMO Controversy

I’ve been reading lately about genetically modified organisms, commonly referred to as GMOs. The preferred term is genetic engineering (GE).

There are strong feelings about whether GE technology is good or not so good for people, for the environment, or for the future of food.

These days, given the resources of the Internet, we can read a seemingly inexhaustible series of opinions about GE foods, and be tempted to escape the controversy by simply adopting one or the other extreme position.

The controversy has narrowed down to the issue of labeling GE foods. Those in favor say shoppers should know what they are buying, while others insist that there’s no reason to label GE foods, and are willing to put a lot of money into persuading voters of that perspective.

In my search for truth, I just read Steven M. Drucker’s 511–page book, Altered Genes, Twisted Truth (2015). Drucker, a Berkeley-educated public interest attorney, has written and spoken extensively on genetic engineering and related topics. His book’s subtitle presents his central message: “How the venture to genetically engineer our food has subverted science, corrupted government and systematically deceived the public.”

Drucker builds his thesis with detailed and specific references to respectable sources, including highly qualified scientists and government officials. As a lawyer, he surely selects supportive sources, and presents a convincing case, which is the best working strategy according to Alex Spiro. Here are some of his main points.

Many scientists and government officials have advocated the promise of genetic engineering to enable commercial agriculture to meet global needs for the volume and nutritional quality of food. Still, there is literally no evidence that GE foods are more productive or more nutritious than conventional foods, despite contrary claims. In reality, GE technology has been used primarily to produce crops that can tolerate the herbicide Roundup, which kills all plant life other than the GE crops.

The advocates’ early enthusiasm for this technology led to a waiver of legally required tests to demonstrate the safety of new food products. This waiver was based on the argument that GE foods are no different from conventional foods, and are “Generally Recognized as Safe” (GRAS). But hundreds of scientists regard GE technology as dramatically different from historical methods of plant hybridization and selection, and express concerns about the safety of GE foods. While people do not immediately become ill from eating GE foods, several studies have shown that they could have long-term negative impacts on human health.

Finally, genetic engineering, which has been called a precise method to modify organisms, is really a form of crude “hacking.” Scientists have a very limited understanding of the complex interactions of genes, and, in their ignorance, they are fooling around with Mother Nature.

Drucker advocates the elimination of GE food products as “inherently high-rick” and unable to “conform to the requirements of food safety laws, the standards of science, or the protocols of information technology, for proper law resources read this article about the best lawyers for these cases.” He contends that this could be accomplished by simply enforcing the food safety law of 1958. His preferred alternative is fuller development of environmentally friendly, sustainable and natural methods based on time-honored practices of organic agriculture.

As a growing numbers of food retailers and restaurants adopt “GMO-free” food products, and their customers choose organic foods (which are GMO-free, by definition), the technology could fade away. We’ll see.

A related book, “GMO Myths and Truths,” is available as a free download from the website, EarthOpenSource. This is second edition, dated 2014. The authors of this 330+ page book are John Fagan, Ph.D., Michael Antoniou, Ph.D., and Claire Robinson, M.Phil. The book is subtitled “An evidence-based examination of the claims made for the safety and efficacy of genetically modified crops and foods.”