Houseplants Bring The Outdoors In

70927thumbPhilodendrons, dracaenas, ferns, palms or any sort of tropical foliage inside our homes only create an illusion of closeness to nature. Naturally, these plants live in very different climates, mostly thousands of miles away. Not only do they have no business in our homes; they have no business on the North American Continent. Some can live in the garden, but only with unnatural watering.

They are only known as houseplants because they ‘can’ live in the house. Almost all are from tropical regions; and most are understory plants that naturally live in the shade of larger trees. They work nicely as houseplants because they tolerate the shade of home interiors. Because they are from tropical regions, they have no concept of winter, so do not need chilling for winter dormancy.

The disadvantages to their tropical heritage is that they are confined to domestic lifestyles here. Many would not survive frosty winter weather. Some might survive, but would not be happy about it. Others would not like the aridity (lack of humidity) during the summer. Houseplants that get moved out to the garden for part of the year must be grown in pots so that they can be moved back in.

While inside, there are no natural predators to control the insects that feed on houseplants. Scale and mealybug can proliferate enough to not only damage houseplants, but to also make a mess of their sticky honeydew below the houseplants they infest. Spider mites can proliferate where dust accumulates on foliage. That is why houseplants sometimes like to be rinsed by a gentle rain.

Since they are confined to pots, houseplants must be watered more carefully than plants that get to disperse their roots out in the garden. Some large Boston ferns and spider plants may need quite a bit of water to be applied very regularly. Some dracaenas, palms and ficus trees may want to get slightly dry between watering. As soil deteriorates, old plants might need to be repotted.

Houseplants are grown for their lush evergreen foliage, and such lush foliage can be sensitive to fertilizer toxicity. Even if fertilizer is applied lightly, toxins can eventually accumulate if fertilizer is applied very regularly. This problem is usually corrected with repotting. However, plants that never need to be repotted might like to be taken outside to get water rinsed through their potting soil.

Heat Lingers With Indian Summer

70920thumbIt is still too early to say if, or for how long, warm Indian Summer weather will linger into what should be autumn. This last spell of unseasonable heat (in California) was merely a heat wave. Of course, at the time, there was nothing ‘mere’ about it. It was downright hot! It was weirdly humid too. As uncomfortable as it was for us, the humidity made the unseasonable heat more tolerable for some plants.

Heat has a nasty habit of drying things out. Humidity does the opposite, although not quite as efficiently. Many plants might have been seriously desiccated if the weather had gotten so warm without the humidity. A cooling breeze might have made things more comfortable for us, but likewise would have been more uncomfortable for plants by enhancing the desiccating effect of heat.

So, again, we disagree with our plants. One thing we all agree on is that this last heat wave was unseasonable, and came at a time when summer should be on the downhill side toward autumn. Some evergreen plants are producing foliage designed for cooler weather. Worst of all, many of the gardening procedures that get done this time of year are in anticipation of cooling weather.

Not too long ago, pruning and shearing of hedges and other evergreens was an important topic. The objective was to get it done one last time before autumn. If done too late, new growth develops slowly through the cool winter weather, and is more susceptible to discoloration and frost damage. Now, the problem is that some of the fresh new foliage was scorched by the heat!

Also, fertilizer should have been applied one last time before autumn. Later application stimulates new growth so late in the season that it is sensitive to frost through winter. Just like pruning, the fertilizer stimulated new growth that might have been damaged by the heat. So, proper pruning and application of fertilizer to limit frost damage may have left plants more susceptible to scorch.

Just like with frost damage, scorched foliage should not necessarily be pruned away immediately. If not too unsightly, it might be best to leave it alone. Some evergreen plants will not replace it until next year anyway. Deciduous plants will shed it when convenient. Large leaves like those of philodendron and banana, may deteriorate so badly that pruning them away is the best option.

Street Wise About Street Trees

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There is no such thing as a perfect tree. All trees have foliage that one way or another, eventually falls to the ground. All trees have roots that might try to displace something that gets in their way. Many trees are messy in bloom. Some make messy fruit. Except for palms, all trees have branches that can be broken by wind. Just about any tree can be blown over if the wind is strong enough.

This is why the selection of trees that are appropriate to each particular application is so important. Finding trees that provide enough shade, obscure an unwanted view, or perform any specific function is one thing. Finding trees that behave while performing their assigned tasks is something else. There are always compromises. A certain degree of bad behavior will likely be tolerated.

Street trees for a parkstrip between the curb and sidewalk can be the most challenging trees to select. There are so many variables to consider. Many neighborhoods have saved us the trouble of selection by prescribing a specific tree, or maybe limiting the choices to only a few species, whether or not they are actually appropriate. Otherwise, we are on our own, to select whatever we like.

Microtrees might seem like good choices. They do not get big enough to damage a sidewalk, or make much mess. These are trees like crape myrtle, purple leaf plum and photinia (in tree form). These trees can be proportionate to narrow streets, but really do not shade much more than a single parking space. Because they are so low, they need serious pruning for adequate clearance.

Mid-sized and bigger trees like Chinese pistache, honeylocust maidenhair tree and some of the modern hybrid elms certainly cause more problems, but might be worth the bother. They shade curbside parking and part of the front yard nicely. Like small trees, they need to be pruned for clearance, especially over the roadway, but they eventually grow up high enough to be out of the way.

It seems that trees that exhibit some of the better characteristics for street trees are deficient in other ways. Australian willow has very complaisant roots, and is very resilient, but also branches low, and is not much to look at. Fern pine and several oaks are excellent street trees for decades, but eventually get big. Root barriers will delay, but not prevent roots from damaging sidewalks.

Timing Is Everything For Pruning

70906thumbThere are certain disadvantages to gardening in such a perfect climate. We can not grow things that require significant chilling in winter. Nor can we grow things that require prolonged heat in summer. Seasons change so gently that it is easy to get behind schedule. It is already late summer, whether it seems like it or not. What we do not do in the garden is as important as what we do.
Plants know what time it is. Almost all are slowing down significantly. Many natives do almost all of their growth in spring, and then spend the later half of summer just getting ready for autumn. By now, the buds of deciduous trees like sycamore, oak and willow are already getting plump, even though they will not do anything until the end of winter. Non native plants will not be too far behind.
Evergreen plants that get pruned or shorn a few times through summer might need to be pruned or shorn one last time. If not done now, it probably should not be done any later. They need a bit of time to recover and regenerate a little bit of new growth prior to autumn. Otherwise, the exposed inner growth will stay exposed, and get worn by the weather as summer progresses into autumn.
Some plants need a bit more time to for new growth to mature than others do. Privet hedges for example, are quite tough, and do not seem to mind getting shorn at any time. New growth of holly, pittosporum and photinia gets stunted and discolored if still trying to grow as the weather gets too cool for it to continue. With enough time, new growth starts, and then ‘hardens off’ before autumn.
Like pruning, fertilizer promotes new growth, so should likewise not be applied too late. One last application of fertilizer can improve the color of citrus foliage before winter. Greener lemon and lime foliage tends to be more resilient to frost. Iron is particularly helpful for foliage, and is less likely than complete fertilizers are to stimulate new growth that will be sensitive to frost later in winter.

Flowers Might Be Getting Scarce

70830thumbIt makes sense for flowers to bloom in spring. Winter is too cool, windy and damp for both flowers and the insects that pollinate many of them. By summer, successfully pollinated flowers have faded, are busy making seed to disperse in autumn. Some plants produce fruit to get birds and other animals to disperse their seed. There are certain advantages to blooming early in the spring.
Native plants that are endemic to chaparral climates are quicker with bloom, so that they finish before the air gets too arid. Desert plants might bloom for less than a week. Some tropical plants might bloom whenever they want to because they do not understand the concept of seasons, but they are not the prominent plants in our gardens. Therefore, flowers get scarce this time of year.
Besides the few perennials and annuals that bloom as long as the weather stays warm, there are not many plants that bloom reliably so late in summer. Belladonna lily, which is also known as naked lady, might be one of the flashiest, as its bright pink flowers bloom on top of bare stalks before the low basal foliage develops. It was actually dormant through the warmest part of summer.
Billowy and bold pampas grass flowers bloom this time of year, but are uncommon. The boldest type of pampas grass is too big and difficult to manage for home gardens. The smaller type has dingy tan flowers, and is so invasive and weedy that it is unavailable in nurseries. Those of us who have it in our gardens did not plant it. Other grasses with nice late flowers are not very colorful.
Russian sage has become one of the more popular late blooming perennials. More traditional Japanese anemone, goldenrod, lion’s tail and showy stonecrop all seem to have lost popularity over the years. Mexican blue sage should bloom best late in summer, but often finishes sooner than expected. Yarrow often blooms later than expected, until summer ends. Marigold, blanket flower and some sunflowers bloom until frost. Chrysanthemums, whether grown as annuals or perennials, are just beginning late in summer.