Washington State University Extension

Garden Tips

Archive for October 2015

Ripening Green Tomatoes

GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written October 2, 2015

Frost is coming and it is likely to be soon. The average date of the first killing fall frost in our area is October 15, but earlier for cooler spots. Before that happens and perhaps even a little earlier, gardeners should start picking mature green tomatoes. As we discussed last week, some types of mature fruit will ripen after picking. Tomatoes are one of them.

Our tendency as gardeners is to leave tomatoes on the vine in the fall until frost threatens and then quickly pick everything we can find that has some color. Some gardeners cover their vines with clear plastic to make a sort of greenhouse to keep the plants and fruit warmer during the day and protect them from frost at night.

However, covering plants with plastic or blankets is not going to help much because the fruit is injured by cool night temperatures below 50 degrees. Exposure to repeated chilly nights will damage the fruit, resulting in more fruit loss from decay. Once night temperatures start dropping below 40 degrees the damage is even greater.

The good news is that mature green tomatoes will ripen very well off the vine and still provide you with the wonderful flavor of homegrown vine-ripened tomatoes. There is no need to pick smaller green tomatoes that have no chance of ripening. Only pick mature green tomatoes. Telling the difference is a little tricky, but not hard. Generally, the fruit should be at least three-quarters the mature size expected for the variety. They will have turned from a bright green to a lighter green or whitish color. They do not need to have started turning red or the expected mature color yet.

Once the fruit are harvested, take them indoors and prepare them for ripening. This is done by first washing them with cool clean water and then allowing them to air dry completely. If any are cracked or split, they are more likely to rot before ripening so throw them out or use them in a recipe that calls for green tomatoes.

After roguing out the damaged tomatoes, you may want to sort those you have left. The ones that have developed a tinge of color will ripen first. Put these in one group, and then sort by “greenness.” The next step for many gardeners varies depending on just how many tomatoes they have and their capacity for storage. I recommend placing them in single layers in covered cardboard boxes. (Leave a little space between tomatoes.) Some folks wrap each fruit with newspaper and then place them in a box, but this is tedious and makes it difficult to check for both ripe or rotten fruit.

Tomatoes are the type of fruit that will ripen after picking and produce ethylene gas as they ripen. Exposure to ethylene gas from another source will speed up the process. If you are in a hurry for ripe tomatoes, place some of your green ones in a closed bag with some ripe bananas or tomatoes because they produce ethylene gas.

Our mothers and grandmothers placed their green tomatoes on the windowsill thinking that exposure to light was needed for ripening. Actually, they need the warmth not the light from the windowsill. Tomatoes will take about two weeks to ripen when kept at a temperature around 65 to 70 degrees. Cooler temperatures, but above 50 degrees, will result in slower ripening.

A chills is in the air so start harvesting your green tomatoes for ripening. Now is the time for action!

Fall Color is a Treat

GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written October 11, 2015

Fall is my favorite season of the year. Last week when I was in Spokane, I experienced exquisite tree and shrub fall color. What a treat! This change of leaf color from green to intense yellows, oranges, burgundy, and bright red has always been amazing to me. I can remember as a young girl collecting leaves each fall and my mother helping me iron them between two sheets of waxed paper. Did you ever do this?

Of course there is science behind this awesome transition. During the growing season most tree leaves are green. The green color in leaves is due to the green pigment chlorophyll. Also produced in the leaves are yellow (xanthophyl) and orange (carotene) pigments that are usually masked by the green chlorophyll. In the fall, as the days shorten and the weather cools, chlorophyll production slows and the chlorophyll already present starts to break down, revealing the underlying yellow and orange pigments.

What about red? Anthocyanins are the red to purple pigments in plant tissues. They are sometimes present during the growing season in plants with reddish to purple leaves, like red barberry or Crimson King maple. However, the red and purple pigments that show up in autumn are the result of anthocyanin production that starts as chlorophyll production slows and sugars in the leaf increase. Leaf sugar content and anthocyanin production is greater when sunny days and cool nights prevail, providing more intense fall colors and a more spectacular display.

Why do some trees like gingko and birch only have yellow and gold fall colors and others like red maple and scarlet oak have orange and red fall colors? While the amount and intensity of autumn leaf color is related to growing conditions and weather, the type of colors a tree is capable of producing depends on its genetic makeup.

What about trees that turn brown or copper in the fall? As just noted, some trees are not genetically programmed for fall color. Many types of oaks do not have a colorful fall display. This is because their leaves contain plant compounds called tannins. They are present all season long, but are also masked by chlorophyll. When the chlorophyll disappears, the brown tannins become visible.

Every fall I long for the beautiful autumn color display put on by the sugar maple forests of the northeast. Thankfully, that yearning has been assuaged a bit as more homeowners and municipalities have planted tree species that provide marvelous fall color.

Sugar maples do not thrive in our local climate but red maples do grow well and provide nice fall color. Two of my favorites are the red maples, especially Autumn Blaze with orange-red fall color and October Glory with orange to red color. You also can not beat the bright golden yellow of gingko trees like Autumn Gold, another one of my favorites for fall color. Add to that list Tiger Eyes sumac, American sweetgum, flowering dogwood, scarlet oak, and red oak.

If you want to plant a tree with great fall color, visit your favorite local nursery soon to pick a tree tree with the fall color that you like the best.

The Dilemma of Determining Fruit Maturity and Ripeness

GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written September 27, 2015

Gardeners are often faced with the dilemma of knowing when to harvest their fruits and vegetables. When is the right time to pick them and will they ripen afterwards? At the risk of revealing that I am a botany nerd, technically fruit are the protective female organs of flowering plants that contain their “babies” or seeds. The protective fruit may be fleshy structures like apples or dry structures like nuts. Apples, peaches, grapes, tomatoes, peppers, and melons are all examples of fleshy fruit.
Physiologically, fruit are mature when their seeds are fully developed. However, if you have ever encountered a humongous fully mature zucchini you will know that the desirable stage for harvesting and eating this “fruit” is when they are much smaller with tender skin and undeveloped seeds. As consumers, there are some vegetable fruits that we prefer to eat when they are immature, like summer squash, and others when fully mature, like melons. When it comes to tree fruit like apples or peaches, we usually find the fruit much tastier when fully mature and ripe.
Ripening is also a physiological process. It involves changes in the fruit, such as the flesh becoming softer and sweeter and the skin changing from one color (often green) to another. A variety of chemical changes can occur during ripening, including the breakdown of starches into sugars leading to a sweeter flavor. Softening results from a change of insoluble pectin in the cell walls to soluble pectin. The acid content of the flesh also decreases as the fruit ripen.
Now back to the original question of when to pick fruit and if they will ripen off the plant. The answer is some do and some do not. Because of this, horticulturists divide fruit into two groups. The group that do not ripen after picking tend to produce only small quantities of ethylene gas as they ripen. Ethylene is an odorless naturally occurring hydrocarbon gas. It is sometimes referred to as a plant aging hormone. Fruit that do not ripen after picking include cherries, grapes, raspberries, strawberries, other berries, watermelon, and citrus fruits. These are picked when fully mature and ripe.
The second group are fruit that produce greater amounts of ethylene as they ripen and do ripen after picking. These include apples, pears, peaches, nectarines, apricots, plums, cantaloupes, bananas, and tomatoes. These fruit should be harvested at the “right” stage of ripeness after becoming fully mature. I am sometimes asked how to determine when to pick homegrown apples. It is tricky as the timing is based on the color of the skin, how easy it is to detach from the tree, flavor, and softness.
Commercial fruit growers have equipment for testing skin color, amounts of sugar, and flesh firmness. Gardeners should periodically check for sweetness by tasting the fruit. The flesh will be starchy if it is not ripe. Gardeners can also use their noses to check the fruits’ aroma and their eyes to judge skin color. Apples change in firmness from rock hard to slightly softer flesh that gives just a bit with a press of the thumb. Ripe apples should separate from the tree fairly easily with a slight upward twist. A gardener must sacrifice a few fruit to determine the “right” time, but it is better than harvesting an entire crop of unripe or over-ripe fruit.
Now that fall is here, I suspect frost is not far off, so next week we will tackle picking winter squash and green tomatoes.


GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written Septembe 13, 2015

Two years of record heat is just too much. I am tired of seeing samples of crispy brown plants and being asked the cause of the problem. Quite simply, it has been hot and difficult for plants to survive, especially plants that are not well adapted to our climate.

Several weeks ago I took a look at some local Norway and Colorado spruces that were turning brown and dying. While not always the best clue to the origins of a plant, these spruces’ common names do give us a hint that they may not be well suited well to the hot, dry summer weather of the mid-Columbia. Norway spruce is native to northern and central Europe and prefers a cool, moist, humid climate. Colorado spruce, native to the central and southern Rocky Mountains of the US, is also best adapted to a cool, humid climate.

In their publication on “Spruce Problems” the University of Illinois points out that spruces as a group “prefer locations with acidic, well drained soils” and that “spruces are not well adapted to hot dry locations and often suffer when planted in the warmer regions of the US.” In this publication they also discuss heat injury of spruces, indicating that high temperatures can cause heat damage, especially when the high temperatures are preceded by cool weather. Heat damage on spruces is expressed as browning and dropping of new needles, leaving dead branch tips. After two or three years of this, a spruce is pretty much dead.

Just because spruces are not well suited to our climate does not mean that you can not find healthy spruces growing locally. However, our climate does stress them and make them more vulnerable to attack by a number of pests, like spruce mite, bud scale, and needle miner. I did find spruce bud scale on one of the browning Norway spruces, but the infestation was not severe enough to kill the tree. At least we can be thankful that our dry climate keeps fungal diseases that infect spruce from being a problem here.

Flowering dogwood is another tree that suffers when faced with hot, dry, windy summer weather. In its native habitat, it is an under-story tree that grows in the filtered shade of other forest trees. It grows best in a moist, well-drained, slightly acidic soil that is high in organic matter.

Dogwoods become stressed when planted in full sun and subjected to high temperatures, reflected heat and light from pavement and structures, wind, compacted soil, and poor watering practices. This stress shows up as curled leaves and crispy brown leaf edges. Nevertheless, many of these trees still put on a beautiful display of flowers each spring. To help dogwoods better cope with mid-Columbia conditions, plant them where they will have filtered shade and will not be subjected to a southern-western exposure or drying winds.

Dogwoods and spruce have very shallow root systems, making them more subject to drought and heat stress. It is advisable to keep the roots cooler and moist by mulching the roots with wood chip or shredded bark mulch. Apply a 3 to 4 inch layer of mulch all the way out to the tree’s dripline and beyond. Keep the soil moderately moist, but avoid excessive soil moisture. Be sure to water the spruces during the winter if the weather stays dry and mild.

I hope next summer is a little cooler, don’t you?


GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written Septemer 20, 2015

Let’s face it, our lives today are very busy. While we gardeners may not mind spending time in our gardens, only the most devoted rose lovers enjoy the time and hard work it takes to care for traditional rose shrubs. Plant breeders, working to meet the needs of today’s gardeners, have developed easy-care roses that make this beloved bloom more accessible.

Not long ago I mentioned that I was a fan of Oso Happy Smoothie. It is a rose with single pink flowers and a mounded habit, growing about 3 feet tall and wide. It has no thorns, is very winter hardy, and only needs a bit of shaping in the spring. It is resistant to powdery mildew and black spot diseases. It is a continuous bloomer, flowering in early, mid, and late summer, providing an abundance of raspberry pink blooms all summer long.

Oso Happy Smoothie is just one of the easy-care roses promoted by Proven Winners. This year they introduced Oso Easy Lemon Zest, the newest member of the Oso Easy series. It grows about 2.5 feet tall and 3 feet wide, producing lemony yellow flowers that don’t fade to white once open. Like the other members of the series, Lemon Zest requires little pruning, is very disease resistant, blooms continuously, and is self-cleaning. Self-cleaning means that their faded flowers do not require “dead-heading” or removal by pruning back to a bud or leaf to encourage re-bloom that is needed with traditional rose shrubs.

Easy-care roses are not new to the garden scene. The Tesselaar company has been touting their Flower Carpet rose series since introducing ‘Flower Carpet Pink’ 20 years ago, calling it the first “eco-rose.” Pink Splash with bicolor hot pink and pale pink flowers is one of their newer introductions.

Tesselaar indicates that members of their series are low-growing and compact, disease resistant, and require little pruning. They are also continuous blooming and self-cleaning. Depending on the cultivar, they grow about 2.5 feet tall and 3 feet wide. Once established, they are hardy to Zone 5 and tolerant of low water and drought conditions. Their “Next Generation Flower Carpet” cultivars, Amber, Pink Supreme, and Scarlet, are more heat tolerant than the older cultivars. They recommend pruning these roses back to one third their size in early spring.

The Knock Out series of roses, introduced in 2000, has become poplar with gardeners. Like other easy-care roses, they are winter hardy, continuous blooming, self-cleaning, and disease resistant. They grow about 4 feet tall and wide and sometimes larger. There are currently seven members of the Knock Out series. I am partial to the Double Pink Knock Out for its pretty pink double flowers.

Knock Out roses work well in mixed shrub and flower borders or as a hedge. Pruning is fairly simple. Most years all that is needed is a little pruning in the spring to shape the plant and remove any dead, damaged, or diseased canes. Every several years they need more severe pruning to remove one third of the oldest canes. To maintain them as a hedge, use hedgers to cut them back in the spring to two feet below the desired size.

Some rose experts disdain easy-care roses for lacking the fragrance and beauty of traditional rose shrubs. William Radler, the developer of Knock Out roses, admits that these are not exhibition roses, but are intended for today’s busy gardener who wants low-maintenance roses that require less pruning and less chemicals. However, Radler hopes to develop low-maintenance hybrid tea, floribundas, and other traditional rose shrubs. If he does, that should make all gardeners who love roses happy.


GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written September 6, 2015


This summer was tough on many area lawns, especially those where watering was restricted. Owners of ravaged lawns are wondering what to do now.

The first thing to do is assess the damage. Are spots and areas truly dead or did the grass just go dormant? With cooler weather and more water available, dormant grass should be starting to show signs of life. Check the brown areas closely looking for new grass blades. Once water becomes available, grass that is dormant greens back up within two weeks.

If no green growth is apparent and patches are a crispy yellow-brown or a grayish color, it is likely the grass is completely dead. Fall is a good time to re-seed or re-sod those areas, as long as irrigation water is available.

Because it takes some types of grass seed, like that of Kentucky bluegrass, up to two weeks to germinate, seeding must be done early enough to allow time for the seed to germinate and grow mature enough before hard frosts occur and before irrigation water is turned off. The average date of the first hard frost in this area is October 15th (note this is only an average date), so lawns must be seeded in early September. Re-sodding can be done later in the fall, as long as water is available and the soil is not frozen.

Water is critical to the success of both re-seeding and re-sodding. The soil must be kept moist to enable germination and provide moisture for root growth. If water is not available, you will be wasting time and money.

If more than 50 percent of your lawn is dead, you will probably want to consider complete renovation. You must get rid of the dead grass and any thatch before you can re-seed or re-sod. Seed and sod roots must be in touch with bare soil. Do this by mowing as low as possible and then using a rake, dethatching machine, or sod cutter to remove grass and thatch. Once you have bare soil, apply a starter fertilizer and the seed at the recommended rates on the labels and then rake the seed into the top of the soil.

If “only” 25 to 50 per cent of your lawn is dead, complete renovation can be avoided with over-seeding. First mow the lawn at a height of one and a half inches. Then you will need to rent a machine called a slit seeder or find a lawn care company who can come in and do this for you. The slit seeder cuts down through the grass and thatch and into the soil, dropping grass seed into the slit it creates. If you do this yourself, make two passes over the area in opposite directions. Check to make sure the seed is ending up planted at least 1/4 deep in the soil. Finish up with an application of lawn starter fertilizer and a light raking.

Next, moisture is needed to promote the germination and growth of the seedlings. This can be tricky as you need to water frequently enough to keep the soil moist but not too wet. Excess moisture can lead to disease problems. Once the grass germinates and plants develop several leaves, you should water more deeply and less frequently.

For lawns that survived the heat and are still green and growing, fall is the best time to fertilize. Apply fall lawn fertilizer in early September and again in early November.



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