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June 2006
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August 2006

Cutting Back Perennials

Today I have been thinking about cutting perennials back after they bloom, and doing some of it too. Over the years, I have seen a number of plants cut back before they were ready, others cut back too formally, others not cut back at all when they should have been.

Take for example, Watsonias. I have them in several colors. They are plants that resemble Gladiolus, but taller, more graceful, with smaller, less frilly flowers. After the first flush blooms, you can cut the stem back and shorter side heads of flowers will open up. This happens 3 or 4 times before the plant is finished blooming altogether. Then you wait. The outer leaves begin to turn brown, and, because it is in the iris family, they are tough, best cut with shears at their bases. From here, you have the option of cutting the whole thing down in a few weeks when more leaves turn brown, or cutting them out as they form, but still having the green ones standing. It is best for the plant to let the leaves die back on their own before you cut them, and I'd never cut them until at least a third of them had turned brown, but you have some leeway here.

Another example is lavender. Its blooms are starting to lose their color now, and so soon it should be cut back. I often see plants that were not cut back the previous year, and they look awful! To cut it back, you cut down past the bare stem, to the first or a lower pair of little shoots. When you are done, you want to have a rounded plant, so if any of the stems will be rather tall, you can cut deeper into them to improve the regularity of the silhouette. However, you don't want a sheared look, so it is best to cut each stem individually, so they won't be all the same length.

And then there is California poppy. It is a perennial, contrary to what most sources say. After it blooms out, and becomes a mass of brown stems with seedpods at the end, you can cut it to nearly the ground. Leave a couple of inches of stem, and look for green shoots regrowing near the ground. If you find any shoots regrowing, be sure not to damage them. As with watsonia, you have some leeway. Maybe there are still a few flowers on the plant, but it looks rather awful: go ahead and cut it back.

It is the beginning of the cutting back season. More will follow as different perennials have had their say. It is an important way to keep a garden looking fresh.

More Free Plants

Last year I tried to start African blue basil from stem cuttings in cutting mix and got only one small plant from all of my efforts. This year I put some stems with flowers in water to make a nice, subtle spray of lavender spikes, and left them in the vase for almost 2 weeks. By this time they were sort of bloomed out, so I was about to dump them. But I noticed that the leaves were still not wilting. Hm. Removed them from the water to find most of them were rooting!

Rooting in water usually isn't the best idea, 'cause when you take the cutting out of the water, the new roots tend to clump together. Better if you can root in some kind of rooting medium, like perlite with a little bit of peat moss mixed in, or even potting mix, so the roots can get kind of distributed through the medium. But water it was, so I have potted up 6 rooted cuttings. First I clipped out all of the flowering stems, then I set the cuttings in individual 2" diameter plastic pots, separating the roots as much as I could. Then I set the pots in a small styrofoam tray and covered them with a clear plastic bag. I kept the setup out of the sun.

After 2 days, I have uncovered the plants and 5 of the 6 are OK. The 6th is wilting, and probably won't make it.

The African blue basil parent plant in my community garden is blooming exuberantly and is about 3 feet tall and across. I am suddenly overwhelmed with basil. After years of struggling to grow the stuff, I could now make pesto twice a week if I wanted to. An amazing plant!

In any case, I now have 5 new free plants to plant at the City College garden, where the cold, windy microclimate will probably keep them much smaller, but still bigger than any other basil would be there.

If you would like to read my last summer's SF Chronicle article on African blue basil, you can do so at:

I love free plants

I've been thinking that a different name might also have been appropriate for my book, which is titled Wildly Successful Plants: Northern California  I could have called it Free Plants and How to Grow them Well. They are all plants that naturallize, meaning that they regrow, from seed, cuttings, divisions, bulbs, etc. Professional gardeners sometimes call them "the free stuff" and use them to replace expensive plants that have died in gardens. All of these plants can be had for free, by asking for a start or for seeds from someone who has them, or by starting more of them from your own starts or seeds.

Yesterday I was reaping the benefits of some nice reseeders in my garden. They are annual plants, ones that reseed themselves in less than a year and then die. In a shady part of the garden, I have been transplanting some self-sown seedlings of Ipatiens balfourii. This plant flowers in full shade, bearing two-tone lavender flowers of an interesting form. In fact, some call it the Poor Man's Orchid. (Maybe Poor Woman's as well?) In any case it is pretty and the flowers dance nicely in the slightest breeze. A few reseed every year and I always have enough.

I started Paludosum daisy in a friend's garden, where it reseeds lightly. I brought home 4 plants, added them to the one seedling I found in my garden, and placed them strategically to add their little white daisies to my fall sun garden. Then I found seedlings of an annual mentioned in the book, Echium vulgare 'Blue Bedder'. I planted 5 of those where they will hold their blue flowers above and behind the paludosum daisies. They will be between the daisies and the California native perennial Grindelia, or gum plant. This one will be covered with yellow flowers in the fall, so I will have the blue between the yellow and the white, with the yellow centers of the daisies to echo the yellow and tie the planting together.

Hmm. Since I was in propagating mode, I found myself eyeing the Grindelia. Would a cutting work to make more plants? No, my research says it will work better to layer the plant, that is bury the middle of a couple of the leaning over branches and see if they will make roots. Think I will try it. I love free plants.

Habitat Earth and Our Gardens

An editorial in the July 3rd New York Times under the heading "The Rural Life" is about observing birds. The author, Verlyn Klinkenborg, has begun to notice that birds occupy certain "spacial dimensions" as they live among us. That is, the redwinged blackbird lives in the marsh, the meadowlark hunts from the fencepost, the phoebes hunt bugs low to the ground, the barn swallows higher up, the catbird in the thicket at the edge of the lawn. He (I think the name is masculine) is struggling with the concept of habitat, that a bird can't choose to live a certain place, the way a human chooses to live in a particular city.

I quote: "It takes an act of will on our part to remember how profoundly, and how beautifully, bound to habitat all the other creatures around us really are."

I am struck by more thoughts than I can record. One is that most people indeed, may not understand habitat, and the chain of eaters that make up an ecosystem. I saw a Nature program on KQED Public television a few weeks ago that illustrated the concept beautifully by showing how a fig tree growing in the wild, in Africa, served as a host for many many creatures who depend on it for food. And then some of the creatures on the tree are eating others on the tree. There were the wasps that breed in the figs, pollinating them, the creatures that eat the emerging wasps, the creatures that eat the ripe figs, and the ones that hunt them, ones that eat the leaves of the tree, and so forth. And of course there is all of the life related to other food chains in the same place, and all of the invisible life in the soil and of microorganisms. If this ecosystem is disrupted, some of these creatures will not be able to survive in it. Unlike humans, most creatures are slow to adapt to new conditions and simply die if their accustomed food isn't available.

We think of our gardens as nature, and of course they do contain many of the creatures of nature, but they are highly disrupted nature. They are anthropocentric, human centered, selections from nature. They are not wild ecosystems. Even our native plant gardens are not the same as wild ecosystems. We select what we want in our gardens. We do not invite the poison oak (a major food for the California state bird, the quail) or the rattlesnake. We don't encourage bumblebees to make a nest in our small urban gardens. We want the birds and the butterflies, but not the skunks and the cougars. And humans have also inadvertently brought to our gardens nonnative eaters, like European species of snails, that don't have much in the way of predators native to our gardens.

(If the fig tree of the Nature story were in a garden, along with all of its many eaters, the human would become just one among many eaters, competing for the fruit. And the tree would not be beautiful, but mangy and eaten. Humans would even be in danger of becoming the prey of a larger animal.)

Because we eliminate some of the links in the chain in our gardens, and introduce new creatures, we then have a different proportion of the remaining creatures than would exist in the wild. Because of this disruption, sometimes we have a huge population of eaters that are destroying something we really wanted to enjoy looking at in a perfect state, or that we wanted to eat up ourselves. Here our options are to let the critters have the plants (though if the habitat were completely undisturbed, some other creature might not let them eat as unmolested as they are in our garden), or try to reduce the population of eaters.

Integrated pest management is the best strategy yet devised to deal with the situation. It entails, first, a decision whether the pest damage is intolerable. If not, let it be. If so, you begin a careful logical progression of possible solutions, starting with the ones that are least likely to harm natural predators. If you can't find a way to solve the problem without more harm to natural predators than you want to cause, you can stop short of a solution that might save your plants but might also kill something you want to spare. But often you can find a less draconian solution.

Some people choose to garden following "organic" principles, which means using few or no chemicals.Using IPM logic is a great help to them as well, giving them many many tools that manage pests in ways that improve the balance of the habitat.

Birds are indeed habitat dependent, and a story in the July 4th SF Chronicle by Environment Writer Jane Kay, says that bird extinctions are on the rise. Some birds can use our gardens as habitats, if we plant something that feeds them, like native berried bushes, or use few or no pesticides, so the insects they eat won't poison them, but other birds need marshes or forests, or African fig trees in the wild, so the problem is wider than our gardens.

In the final analysis, we ourselves are not really free of habitat limitations. We have learned to use many different natural habitats, and to ship materials to house, clothe and feed us so we can live in cities and other habitats that don't provide our basic needs on site, but our habitat is the planet earth, and if we make it inhospitable for ourselves, we will not be able to make a living on it.

Not so cheery, eh? But gardening is a way into understanding this stuff, and knowledge, as they say, is power.