Washington State University Extension

Garden Tips

Archive for October 2010


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Back in July, I promised to followup with information on solving the problem of iron chlorosis due to alkaline soil conditions. I know many of you have been on pins and needles waiting so here we go…

In an ideal world, we gardeners would have a soil test done before planting our landscape. A soil test would tell us the pH (acidity/alkalinity), as well as potential lacking nutrients needed for healthy plant growth. In that same perfect world, we would avoid planting plants not well suited to our local alkaline soils, such as rhododendron, blueberries, silver maple, and pin oak.

In reality, few of us check our soil pH before planting or selecting our landscape and garden plants. With that said, what can we do to mitigate the problem of iron chlorosis due to alkaline soil?

First, gardeners should check to see if high pH is the problem. Similar symptoms of chlorosis can be produced if the plants are over-watered, under-watered, growing in compacted soil, or have failing root systems. This means reviewing cultural practices AND having the soil tested.

The addition of elemental sulfur to the soil after planting is not recommended. This can help if done before planting, but not after. Sulfur does not dissolve. It’s ground into fine particles and mixed into the soil where only the soil in the immediate area of each sulfur particle is acidified. Sulfur applied at the surface doesn’t work its way down into the root zone where it’s needed.

Experts recommend several options for addressing the problem of alkaline soil. First is mixing equal parts of ferrous sulfate and elemental sulfur and putting the mix into holes placed in the root zone of trees and shrubs. Over time (months and years) this mix will acidify the soil close to the holes and the effect may last several years. (Examples of products with iron sulfate plus sulfur are Copperas, Jirdon Super Iron Green, Hi Yield Soil Acidifier Plus Micros, and Fertilome Soil Acidifier Plus Iron.)

A costlier route is adding iron chelates to the soil in the same manner. An iron chelate is a material where the iron molecule is protected by a larger molecule. This larger molecule keeps the iron in an available form until it is broken down by soil microbes and soil alkalinity. The response to the iron chelates is quicker, but will not last as long as the sulfur/ferrous sulfate mix. (Look for iron chelates with the FeEDDHA molecule. This includes Monterey Sequestar Iron 6%, Sequestrene 138 and Millers Ferriplus.. Other iron chelates for soil application are available, but don’t work well when the pH is above 7.2.)

If a quick fix is desired, there are iron chelate materials that are applied as sprays to the leaves. The leaves green up quickly, but this is primarily a cosmetic treatment and does nothing to help solve the underlying problem of high pH. Leaf response from chelate sprays can be uneven and the “greening up” may not last all season, especially if there is new growth after application.

Some garden stores may recommend the use of aluminum sulfate to acidify the soil. Repeated use of this product can lead to aluminum toxicity and isn’t recommended. Materials injected into the trunk of a tree are also ill advised since they create wounds that can result in wood rot.

The iron applications I’ve mentioned are worth a try, but if they don’t work, consider replacing the chlorotic plants with ones that are more tolerant of alkaline soils.

Published: 9/18/2010 1:29 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

We waited so long for our growing season to start and now many of us are anxious to bid it adieu. Months of watering and grooming annual plants becomes tedious as the production of flowers begins to wane. It’s easy to say goodbye to many of the annuals. They’ll be relatively inexpensive to replace next year, but garden geraniums are a costlier item. Frugal gardeners have found several ways to “recycle” or overwinter their geraniums for growing again next year.

One way is by taking cuttings of the desirable plants and starting new ones. Use a clean, sharp knife to take stem tip cuttings that are four to five inches long. Remove the leaves on the lower half of the stem and then dip that end into rooting hormone. Rooting hormone products stimulate rooting and can be purchased at garden stores. Stick the treated end of the cutting into pots filled with moist perlite.

These should be placed where the humidity can be kept fairly high. You can use one of those little plastic “greenhouses” sold for growing transplants from seed or just use a zippered plastic bag as a “greenhouse.”

Check your greenhouse periodically to make sure the perlite is still moist and that none of the cuttings are rotting. Remove any rotten cuttings. Place the greenhouse where it will get lots of light, but no direct sunlight. If heavy condensation builds up inside, open it up a bit to air it out and then close it again.

If all goes well, the cuttings should root in about five to eight weeks. Once the roots are at least an inch or so long, remove them from the greenhouse and plant them in individual small pots with a quality potting mix. These should be placed where they can get as much sun as possible. As they get larger, pinch out the growing tips to encourage branching.

Another way to overwinter potted geraniums is to cut the tops back to a height of six inches. Place the pots in a box, cover the plants with sawdust, and then store the box in a cool (40 to 45 degrees) area. The soil should be slightly moist, not wet, when you box the plants up. Periodically check them and add water if needed to keep them from shriveling.

One method I don’t recommend involves digging up the geranium plants, shaking the soil from the roots, and hanging them upside in a cool basement. This can work if you have a cool, humid (80 per cent humidity) basement, but this situation is seldom found in most homes today, especially in our region.

An alternative to this method is digging the plants, gently shaking the soil from the roots, and placing them individually in large paper grocery bags. (Recycle!) Store the bags in a cool (45 to 55 degrees), dry location such as an unheated bedroom. Once a month take the plants out and soak them in water for a couple of hours. Let them dry off before returning them to their bags.

In early spring (March or April) these bare-root plants can be potted up after shriveled stems and dead leaves are removed. Place the pots in a sunny spot to encourage new growth. After danger of frost has passed, they can be planted outdoors.

If you have some garden geraniums you just don’t want to part with or you want to save some money next season, why not try recycling your geraniums this fall? Make sure you get this done before the plants are damaged by frost.

Published: 10/2/2010 1:21 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

The Mid-Columbia Community Forestry Council has named the red maple, Acer rubrum, the Mid-Columbia Tree of the Month” for October. Red maple is the perfect choice to recognize because it has outstanding fall color and performs well in local landscapes. Growing up in the northeast part of the country, I’m a sucker for trees with magnificent fall color. That’s why you’ll find an October Glory, a cultivated variety of red maple, in my yard. The leaves on my tree are just beginning to show tinges of red, so I’m anxiously anticipating glorious color by the end of the month.

Red maple is an excellent shade tree for use in home landscapes. This native North American species grows to from 40 to 60 feet tall and 25 to 35 feet wide, although many of the cultivated species are smaller in stature. In the spring it’s one of the first trees to flower with small clusters of red flowers. While this tree prefers both slightly moist and slightly acid soils, it will tolerate wetter or somewhat dryer conditions. It can exhibit chlorosis in highly alkaline soils, but seems to tolerates most local alkaline soils without any problem.

The red maple is a favorite of many gardeners because of its outstanding fall color ranging from bright reds to oranges and yellows. It’s one tree that can be relied upon for a beautiful autumn display. Some cultivated varieties develop color early in the fall, others a little later. If you live in an area with early fall frost, select one that colors up early.

The other things I like about red maples is that they have few pest problems and have a relatively fast rate of growth, without causing as many problems as some fast growing trees, such as silver maple. This is because their root system is less vigorous and aggressive, but the red maple does have shallow roots that develop into surface roots as it grows older.

The smooth, silvery bark of young red maples contrasts well with the green leaves of summer or the bright fall colors. However, some owners have found that cats find the bark a great scratching post, causing significant damage to the tree. Red maple leaves tend to be a little tougher than those of other maples and less prone to tearing and tattering from windy conditions.

October Glory is one of the favorite cultivated varieties of red maple because of its long lasting intense red fall color. It’s very popular and readily found at local nurseries. It grows from 40 to 50 feet tall, averaging about a foot of growth a year. Another popular variety is Red Sunset which colors earlier than October Glory with outstanding oranges to reds. Autumn Flame is another highly touted variety that colors up with red leaves about a month earlier than October Glory. If you don’t like raking, you might want to know Autumn flame also has smaller leaves .

There are also some hybrids (Acer x freemanii) of red maple and silver maple that are often sold as red maples. One of these is Autumn Blaze with long lasting orange-red fall color. It’s a very hardy, fast grower, but tends to be weak-wooded.

Visit your favorite local nursery and check out their red maples now. Even if you don’t intend to buy and plant until next spring, you can check out the fall color of the different red maple varieties and decide which one you like best. That’s what I did.

Published: 10/9/2010 12:56 PM


written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA

Over the summer, I noticed lots of yellowjackets industriously foraging amongst my petunias and other flowers. I kept a respectful distance, but they didn’t pay any attention to me. I didn’t realize at the time that they were not yellowjackets. They were paper wasps.

What’s the difference? Yellowjackets are specific types of wasps. The western yellowjacket, the common yellowjacket, and the German yellowjacket are the most common ones in Washington. Most are about one-half inch long and black in color with jagged yellow bands on their back.

An impartial observer might say that yellowjackets are beneficial insects because they’re predators, feasting on other garden insects during the spring and early summer. They chew up their insect dinner and then feed it to developing larvae when they return to their nest. In repayment, the larvae feed the workers with a nutritious liquid that they produce.

In late summer and early fall, the sustenance provided by the larvae dwindles along with the ready supply of insect prey. Aggravated, hungry yellowjacket workers start aggressively scavenging for other sources of protein and sugar, such as soft drinks, picnic food, garbage, carrion and more.

Paper wasps, another specific type of wasp, are easily confused with yellowjackets. They look much like a yellowjacket except they have a slimmer, more elongated body and they fly with their legs dangling downwards. The golden paper wasp is native to the west, but it’s been displaced in urban areas by a non-native, the European paper wasp. These are probably the “yellowjackets” I’ve seen in my flowers. Paper wasps are also good predators, attacking soft-bodied insects, but the adult workers get their sustenance from flower nectar and other natural sources of sugar.

Paper wasps are generally not considered aggressive. However, they do sting when threatened with physical contact. The European paper wasp is not afraid of human activity, often building nests in protected spots around homes, such as under eaves, in retaining wall spaces, on play equipment, and patio furniture. That’s why it’s often the cause of many human insect stings in the Northwest. Gardeners who unsuspectingly come across a nest amongst their garden plants will frequently be attacked. (Wear your garden gloves.)

Fall is the season when yellowjackets become a hazard for anyone trying to picnic or eat food outdoors. In recent years, the Western yellowjacket, has become a serious agricultural pest in orchards and vineyards at harvest time. The invasive European paper wasp has also become a serious sting risk. That’s why Dr. Peter Landolt USDA ARS researcher at the USDA Agricultural Research Laboratory in Wapato, has been working on developing chemical attractants for use in traps. He successfully isolated two compounds from fermenting molasses that can be used to attract yellowjackets, paper wasps, and hornets. These attractants are used in traps marketed as RESCUE! W.H.Y. Trap.

While there are numerous traps on the market that work fairly well for trapping yellowjackets, they don’t attract paper wasps. The RESCUE! W.H.Y. trap attracts does. Traps are used most effectively when placed outdoors in early spring when daytime temperatures are consistently 70 degrees or above. This catches the queens as they come out of hibernation and before they start new colonies. (The queens are the only yellowjackets and wasps that survive over the winter. New nests are built each spring.) If you have problems with yellowjackets or paper wasps, remember to place traps out early next spring.

Published: 9/11/2010 12:30 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

One of the few insects that gives me the heebie-jeebies are ants. I don’t know why, but they do. However, despite my aversion to ants I do appreciate their place in the environment.

Ants are a social insect, living together in nests with a hierarchal system. Ant colonies usually start with an inseminated “queen.” The queen’s job is to lay eggs, lots of eggs. The eggs hatch into larvae that later turn into worker ants that are all females. As young workers, their job is to care for the babies (larvae) and the nest.

The older, more mature worker ants are given the job of defending the nest or searching for food for the queen and the many larvae. Their quest for food can take them far away from the nest. To find their way back, they will place down a chemical trail.

Male ants are another caste within the typical ant nest hierarchy. The male’s only purpose (you guessed it) is to mate with winged or breeding females. The inseminated females are new “queens” that start new nests. However, with over 14,000 species of ants in the world their life cycles and food preferences vary.

Two of the most common ants in Washington are the pavement ant and the odorous house ant. The pavement ant feeds on various foods like honeydew, insects, pollen, plant sap, meat, grease, nuts, cheese, bread, and honey. They’re a small ant, 1/8 inch or less, and light to dark brown to black in color. Their nests are found in rotting wood and in exposed soil under stones or pavement… giving them their name.

The odorous house ant is tiny, only about 1/16 inch long, and brown to black in color. They prefer sweet foods, such as flower nectar, honeydew from aphids, and fruit juices, but they’ll also eat dairy products, meat, vegetables, and insects. They get their name because of the rotten odor they emit when disturbed.

Generally, ants found in the garden are considered beneficial or at least inconsequential, but they can become pests when they nest beneath plants, undermining the roots or when they take up residence in childrens’ play areas. In lieu of using pesticides, you can discourage them in the garden by raking down their mounds frequently and keeping the area wet. This won’t kill them, but will encourage them to move somewhere else.

Indoors, try using ant bait traps where ants are a problem. The worker ants foraging for food in the area find the poisoned bait and take it back to their nest, killing the queen and the larvae. If possible, place the bait close to where the ants are coming inside. Don’t wipe off counter surfaces and floors before putting a bait trap down. This removes the chemical trail the ants use to find their way back to the nest. Because different ants have different food preferences, try a another type of bait if the first one doesn’t work. (The odorous house ant favors sweets and may be most attracted to the liquid or gel baits. )

If baits don’t work for you, try locating the nest and directly treating it with a pesticide product labeled for this use. There are separate outdoor and indoor ant sprays and baits. Check the label and select the one that fits your situation. With odorous house ants you may need to look for the nests at night, using a flashlight to follow their trails from your house to their nest. If this fails, contact a licensed pest control operator.

Published: 9/4/2010 12:27 PM



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