Pretty? NO!

The Scotch broom pictured here is beautiful while blooming. But this exotic invasive is like standing gasoline during the summer & fall. See the list below of other invasive plants.

When Masanobu Fukuoka, author & guru of The One-Straw Revolution, visited the Northwest he remarked that we should spreed this plant around because it was such a good nitrogen fixer. Shows what carnage can be considered when you're out of your ecosystem.

California alone is home to 4,200 native plant species, and is recognized internationally as a "biodiversity hotspot." Approximately 1,800 non-native plants also grow in the wild in California. Here’s a short list of just some of the invasive plants in California alone. Data is from the
USDA. NAL. National Invasive Species Information Center.

http://www.invasivespeciesinfo.gov/unitedstates/ca.shtml

It’s strange that this list does not include three major invasive plants: ice plant [Mesembryanthemum ssp.], pampas grass, [Cortaderia selloana], and Periwinkle [Vinca ssp.].

NOTE: "3:1 rule: For every year you delay controlling an invasive plant infestation, it will take three years to regain control."

Common Name ( Botanical Name)
Air Potato (Dioscorea bulbifera)
Autumn Olive (Elaeagnus umbellata)

Beach Vitex (Vitex rotundifolia)

Brazilian Peppertree (Schinus terebinthifolius)
Canada Thistle (Cirsium arvense)

Chinese Tallow (Triadica sebifera)
Cogongrass (Imperata cylindrica)

Common Teasel (Dipsacus fullonum)

Dalmatian Toadflax (Linaria dalmatica)

Diffuse Knapweed (Centaurea diffusa)

Downy Brome (Bromus tectorum)

Fig Buttercup (Ranunculus ficaria)
Garlic Mustard (Alliaria petiolata)

Giant Hogweed (Heracleum mantegazzianum)

Hairy Whitetop (Lepidium appelianum)

Houndstongue (Cynoglossum officinale)

Japanese Stilt Grass (Microstegium vimineum)
Japanese World Climbing Fern (Lygodium japonicum) 

Japanese Honeysuckle (Lonicera japonica)

Japanese Knotweed (Fallopia japonica)

Japanese Spiraea (Spiraea japonica)
Johnsongrass (Sorghum halepense)

Kudzu (Pueraria montana var. lobata)

Leafy Spurge (Euphorbia esula)

Medusahead (Taeniatherum caput-medusae)

Mile-A-Minute Weed (Persicaria perfoliata)

Multiflora Rose (Rosa multiflora)

Musk Thistle (Carduus nutans)

Old World Climbing Fern (Lygodium microphyllum) 

Oriental Bittersweet (Celastrus orbiculatus)

Princess Tree (Paulownia tomentosa)
Purple Star Thistle (Centaurea calcitrapa)

Quackgrass (Elymus repens)

Russian Knapweed (Rhaponticum repens)

Russian Olive (Elaeagnus angustifolia)

Saltcedar (Tamarix spp.)

St. Johnswort (Hypericum perforatum)

Scotch Broom (Cytisus scoparius)

Scotch Thistle (Onopordum acanthium)

Spotted Knapweed (Centaurea stoebe)

Tree-of-Heaven (Ailanthus altissima)

Tropical Soda Apple (Solanum viarum)

Whitetop (Lepidium draba)

Witchweed (Striga asiatica) 

Yellow Star Thistle (Centaurea solstitialis)

Yellow Toadflax (Linaria vulgaris)

Green Manures, free nitrogen

It's almost too late plant fava beans, a legume, in the fall. The soil needs to be somewhat warm. This may work in gardens in sunny gardens in the west and south-west gardens. Alfalfa works the best with corn, but this is just for planning next years spring garden. Leave room in your plans to grow some green manures. I'm using another fava bean flower as it's the only one I have without scanning a slide, which I'm to tired to do this morning. :=)

Legumes have gotten a lot of attention because of their ability to fix, via symbiotic bacteria that colonize the plant's roots, atmospheric nitrogen gas into available, "free" fertilizer. Because gardeners are preoccupied with the amounts of nitrogen in their soil, they are often fixated on legumes as a green manure. While legumes are important in a green manure mix, they are not a panacea. And a myth, or lack of understanding, about how this nitrogen fixation really works has confused gardeners and reduced their chances to maximize the nitrogen cycle.

The common perception that growing beans and corn together will help fertilize the growing corn plants is incorrect. Nitrogen-fixing plants, in temperate climates, didn't evolve to directly share the accumulated nitrogen with other plants. The ability to fix free nitrogen "out-of-thin-air", in the bacterial nodules on the roots, is a competitive, evolutionary development. This allows leguminous plants to colonize nutrient-poor soils. Legumes are some of the first plants to inhabit disturbed soils such as landslides, cliffs, beaches, sand dunes, and fire-scorched soil. When you think about it, the compacted clay subsoil that's left after most houses are built is really a disturbed soil. The legumes use all the nitrogen they accumulate to grow and make high-nitrogen seed. While the plant is growing, the nitrogen from the nodules on its roots is temporarily "banked", or stored, in the stems and leaves of the plant. This provides plenty of nitrogen for rapid assimilation into the blossom once seed begins to form. Consequently, the green bean plant growing up a corn stalk isn't about to share its nitrogen with the corn, during the current growing season. The mature beans contain 70 to 90 percent of the entire plant's total nitrogen. After the bean drop is harvested, the roots and their nodules have as little as three to six percent of the plant's total nitrogen--not much of a legacy, or fertilizer portfolio for the "heirs". So, to harvest a bean crop and till under the dry tops of the plant means you'd be getting only a very tiny amount of nitrogen back into the soil because the seed has most of the nitrogen, little nitrogen is left in the stems, roots, and leaves, and the tops are too carbonaceous for easy decomposition. (See illustration on pg. 265 of my "Edible Landscape" book.)

During the growth of a legume, very limited amounts of root nodule nitrogen can become available when the stress of grazing, mowing, drought, or death causes some of the nodules to wither, die, and rot in the soil. This is why the old way of grazing animals on pastures of mixed grasses and legumes works so well. When the cow grazes the pasture, some of the nodules on the legume's roots "shed"--they don't really jump anywhere, they just decompose--the grasses are able to quickly absorb the freed-up nitrogen for their growth. This makes for more pasturage, which entices the cows to eat some more. Meanwhile, the nitrogen-rich legume plants and bulky grasses makes for a goodly amount of nitrogen to be recycled via the bovine posterior--with deposits called meadow muffins, pasture patties, or cow chips.

"Free" Nitrogen with Good Timing

The optimal time to till under a green manure crop for maximum nitrogen (for a subsequent crop) is just before the blooms appear. The conscientious green manurer, must "sacrifice" beautiful blossoms for the optimal amount of nitrogen. I was visiting Ros Creasy one year when almost one third of her front yard had Crimson clover in full, glorious bloom. I timidly mentioned that the best effect for nitrogen occurs prior to bloom, or up to 20 percent of bloom. "Yes," she replied, "I won't get as much nitrogen, but look how absolutely gorgeous the bloom is! I don't mind giving up a bit of the nitrogen for the floral display. Besides, Crimson clover has a decent amount of nitrogen to spare and my soil isn't in horrible shape." Yep.

Let me know what you think.

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Mounded Plantings, Irrigation-Free

I’ve started the annual ritual of mulching the perimeter of my irrigation-free planted mound. I lay down 5 or so sheets of newspaper and then several inches of compost made of rice hulls and manure.


I've always wondered why the former Xeriscape Council only advocated a savings of up to 75% on the water used for outdoor irrigation. Why only 75%? Why not shoot for 100%? After seven years of trial and error, I came up with a mound-and-plant system some eight years ago which has required no additional irrigation beyond the day of planting, even during the most protracted California drought in over 100 years.

To begin such a planting scheme, I stockpiled chunky wood chips (not sawdust, which settles down too much and doesn't drain well) from local tree-trimming services. This is critical that the wood chips are mixed with the fresh green, fresh leaves, and small branches. The leafy green parts are critical to compensate for the carbon in the woodier chips.

Next, I used a spading to just crack open the soil beneath the planned area of the mound, not heaving it. Then, I built an active compost pile and plant directly on top of trimmings. Because tree chips are so high in carbon, I layered or mixed them with some manure if required—if there were not enough leaves. I'd guesstimate that a good starting ratio for your own experiments would be one part manure to three or four parts chips. I would use other types of high-nitrogen materials if needed—wet kitchen scraps, fresh grass clippings, green-manure crops like buckwheat, vetch, bell beans, and clover—to help decompose the woody chips. The more nitrogen added, the faster the mound will decompose and the greater the nitrogen supply for the growing plants. I piled this mixture of high-carbon and high-nitrogen materials at least 50% higher than I wanted the final mound to be, and sometimes up to double the height. I watered each layer as I went and made sure all material was moist.

Next, I covered the mound with a soil cap at least eight inches thick—the thicker, the better. I used a mixture of 50% rotted turkey bedding and 50% native soil for the top layer. The soil cap insures good drainage, a neutral soil temperature, balanced nutrition, and good initial growth for the transplants. The plants are placed into the soil cap and watered in thoroughly. I used five sheets of overlapping newspapers covered by turkey-bedding mulch cover the soil cap and, like a "biodegradable herbicide," suppress all weed seedlings. It’s best for me to plant in the fall so the winter rains continue to keep the composting heap moist and to allow the roots to grow. Drought-resistant plants are essential. I used white, pink, and blue rosemary, grey and green santolinas, rhue, many types of lavender, native sages, euphorbia, daffodils, and society garlic (which the deer started eating a few years later).

Once the mound started rotting, the root-hairs of the plants followed the decomposition to take advantage of the newly available nutrients. Plants are "smarter" than we often acknowledge; their roots won't grow into areas that are too warm due to thermophilic (hot) decomposition over 110 F.

Eventually, my "research" mounds settled down, the shrubs rooted fully into the native soil—the new mound is a wonderful, curvilinear feature in my landscape. Mounded plantings, which seemed to me to be a heap of contradiction at first, have become one of my preferred techniques for quick no-till soil drainage, and they don't require any drip-irrigation hardware or precious water. In hotter climates a bit of drip irrigation will probably be needed. If you experiment with this, please let me know.

There's more about planting on mounds in my book Roots Demystified.

NOTE: I live in a moderate-summer climate with a moderating marine influence. If you attempt this mound-and-plant strategy in your own area, I suspect you'll have to make some changes in plant selection and the time of year you’ll be planting. For example, I once installed a test plot at Kit Anderson’s house near Burlington, VT, when she was editor of National Gardening Association magazine. I spent hours in the muggy August heat, along with members of the NGA staff, hauling in manure-rich straw, distributing Kit's garden clippings and leaves and planting a range of perennials which normally thrive in this northern latitude (within one-half mile of Lake Champlain). Many of the crew were skeptical that such a bizarre method would work, and it didn’t—growth in the late summer was not sufficient to allow many of the perennials to weather the winter in good form. I suspect that timing was the main problem, and that mounds in hot-summer areas need to be planted in early spring so the roots can be deep enough by fall to tolerate the frozen months. You'll have to experiment in your soil and climate. I suspect the mound should be started in the Spring were there is summer rain.

Please post a comment - I want to know how the mound system worked for you.

To see more detail of the illustration put you cursor over the image and double click.

All rights reserved, Copyright 2008

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NOTE: The comments section at the bottom of the post has disappeared. Click on the "___ Comments" button or the title under the "Blog Archives". Thanks, Robert