CO-Horts Blog

Wednesday, November 25, 2015

Is it too late to fertilize a lawn?

Tony Koski, Extension Turf Specialist

Yesterday morning (November 24th) I received this question via Ask An Expert (the national Extension online “help desk” system) and thought it worth sharing.

“We are new to Longmont, CO. Our Lawn Service called my husband and said that they were coming Tues. Nov. 24th for our last fertilization of 2015. I have never heard of anyone putting down fertilizer in late November after two snows??? What is your opinion. Should this be allowed? Will it do any good? Will it harm our lawn? Certainly can't water after the application. Sprinklers have been shut off for a month or more. Please Answer Tuesday if possible!!!! HELP….”

My reply:

Just received this a few minutes ago - so hope I'm not too late to answer.

Fertilizing this "late" is not a problem IF:
1. The fertilizer can be watered in. (But you can' Reason 1 not to).
2. The lawn is still green (I'm not sure if yours is still green? But even if it is green, see reason #1).
3. The ground is unfrozen. (Not sure if yours is still unfrozen? I was on lawns and a golf course in the past couple of days and the soil was already frozen is spots about 1 inch deep).

So, the short answer: I would not recommend that the fertilizer be applied to your lawn at this time (late November). 

Here is a longer explanation of why not (feel free to share with your lawn care company): 
While applying nitrogen now (even if the ground is frozen...and/or you can't water it in) CAN be beneficial to the lawn, there is an important environmental downside to applying N under the current conditions. Research in the northern U.S. (U. Minnesota and U. Wisconsin) has demonstrated that late fall N applied to frozen or soon to be frozen soil (or to turf that has entered into winter dormancy) is at risk for leaching or runoff into places we don't want nitrogen going - like groundwater or surface water (lakes, ponds, rivers). Even if you don't live anywhere near a lake or stream, nitrogen can move from frozen/dormant lawns onto streets (then to storm drains on the street), from where it can be transported to surface water (usually streams or rivers in the Front Range of Colorado). So, to avoid the possibility of N movement into water sources, it is best to avoid very late (like November 25th) fertilization of lawns.
Hope this is helpful - and was received in time!

YES, we still recommend late-season (aka "fall fertilization") of cool-season lawns (bluegrass, fescue) in Colorado. However, from an environmental safety perspective, it is best done during September and October to give the turf ample opportunity to take up the applied nitrogen so that there is much less potential for it to move from the turf into ground and surface water.

Happy Thanksgiving!

Monday, November 23, 2015

Rubies of the Pines (aka Cranberries)

Posted by Deryn Davidson, Boulder County Horticulture Extension Agent

Since this is the week of Thanksgiving, I figured taking a closer look at the little, tart, red fruit that is a staple at most Thanksgiving gatherings, would be apropos. Whether you like to make your sauce from scratch (as my husband does) or if you prefer to open a can and let the cylinder of wriggly sauce slide out (as my father does), the cranberry is something we should all know more about!

The cranberry is in the family Ericaceae also known as the heath or heather family. Other famous members of Eircaceae include the blueberry, huckleberry, azalea and rhododendron. Members of this family prefer moist, acidic growing conditions which we don’t find here in Colorado. Wisconsin is the largest producing state, Massachusetts is second and New Jersey comes in third. In New Jersey cranberries are known as "Rubies of the Pines" because they are cultivated in the sandy, acidic soil and waters found along the Pine Barrens (a heavily forested area of coastal plain). There are several species of cranberry, but the one cultivated here in the United States, and most likely to be found on your dinner plate, is Vaccinium macrocarpon. 

Approximate range of Vaccinium:
Red - common cranberry
Orange - small cranberry
Green - American cranberry
All species of cranberry have similar specific growing requirements. They like sandy soil, rich in organic matter, along slow moving streams or in bogs. They don’t actually grow in water, as some images may lead you to believe. They are a small, evergreen shrub that trails along the ground. 

Herbarium "Vaccinium macrocarpon — Flora Batava — Volume v14" by Janus (Jan) Kops Licensed under Public Domain via Wikimedia Commons 

In late spring the plant produces clusters of long pink flowers. According to lore, early colonists saw the flowers and thought they resembled the neck, head and beak of the sandhill cranes that were often found in areas that cranberries grew wild. They called the plant CRANEberry. At some point the name morphed to CRANberry as we know it today. 

"Vaccinum oxycoccos 120604" by Bernd Haynold - Own work
The fruit of the cranberry have small air filled chambers called bladders and a waxy coating that allow them to float. If you've ever checked out a raw cranberry, you know they have a sort styrofoam nature to them. Native Americans used cranberries raw and cooked as food, medicine and dye for clothing. Mashed together with dried meat, they would make a long lasting pressed cake known as pemmican. Today they are most commonly found as a part of English Christmas dinners and American and Canadian Thanksgiving dinners. The fresh fruits are cooked down into a compote, jelly or sauce as an accompaniment to roast turkey. They are also sold dried and of course processed into juice. They area  good source of vitamin C, dietary fiber and manganese. 

Commercial farming and harvesting of cranberries today is done very similarly to how it was done back in the 1800s. Large areas of land are leveled and surrounded by earthen dikes to create boggy conditions. This allows growers to regulate the water level depending on what stage of the process they are in. Stem cuttings are planted and in three to four years, they begin producing fruit. Harvesting is done by two methods, wet or dry. The wet method, which is most common, involves flooding the bogs above the vines and then running mechanical water reels over the vines to shake the berries loose. Because the the fruit floats, once they are off the plant they can be pushed to the side and loaded into trucks. 

Wet harvest method
Harvest photo  By Keith Weller
USDA-ARS [Public domain], via Wikimedia Commons
The dry method uses a machine with teeth that pulls the berries from the vine and then moves them to large harvest boxes. Before the machines were developed, handheld cranberry scoops were used. Even with mechanical assistance, the dry method has higher labor costs and lower yield, but the fruit is less bruised and can therefore be sold fresh more easily. 

Dry harvest method by hand with "cranberry scoop"

However you choose to enjoy your cranberries this year, hopefully now you can regale your friends and family with tidbits about the mighty cranberry!! Happy Thanksgiving!!

Friday, November 20, 2015

Discover Winter Squash!

Posted by: Carol O'Meara, horticulture entomologist, Boulder County Extension

Are you in the mood to cook with winter squash? It's the perfect time of year to get to know your cucurbits.

Wednesday, November 18, 2015

Composting yard waste

 Kurt M. Jones--Chaffee County Extension Director

As our gardening season comes to an end, rather than throwing away plant waste, many gardeners will compost those materials and help to improve their soils for future years.

Composting is an accelerated way to reduce the volume of organic wastes and return them to the soil to benefit growing plants.  Organic matter improves the drainage and aeration of clay soil.  Compost can be thought of as a separator that “shoulders apart” tightly packed clay particles to allow air and water to enter.  Compost also helps sandy soil hold water and nutrients.  Compost holds moisture like a sponge and releases nutrients slowly into plants as needed.  It also increases the activity of earthworms and other natural soil organisms that are beneficial to plant growth.  Compost should not be thought of as a fertilizer.  The amount of nutrients in compost is limited, but the improved soil characteristics make the addition of compost into garden or flower beds worth the effort.

Choose your composting site carefully.  Partial shading avoids the baking and drying in summer but provides some solar heating to start the composting process.  A site protected from drying winds prevents too much moisture loss.  Choose a site that is close to where the composted materials will be used, but not highly visible or one that interferes with yard activities.

Structures are not necessary for composting, but prevent wind and marauding animals from spreading plant waste.  Structures are also more aesthetically pleasing for your family and neighbors.  The structure should be large enough to handle the amount of yard waste you are likely to produce, yet small enough to be able to mix the contents and remove the composted materials.  A suggested minimum size is 36 inches by 36 inches by 36 inches high.  Some better insulated wood or plastic structures can hold sufficient heat at smaller volumes.

The breakdown of organic yard wastes is a biological process dependent on microorganism activity.  Like most living things, these microbes require favorable temperatures, moisture, oxygen, and nutrients.
Plant digesting microbes operate in a temperature range of 70 degrees F to 140 degrees F.  Well-managed compost breaks down rapidly at internal temperatures between 120 degrees to 130 degrees F.  During the winter months, microbial activity is slowed, thereby slowing the composting process.

Probably the toughest balance to maintain in Colorado’s climate is the moisture and oxygen balance.  Moisture must be added to compost piles to maintain optimal microbial activity.  Too much moisture, however, will limit the amount of oxygen causing the compost to have a foul odor and to not break down.  The best description of the proper moisture level is “moist” or “damp” but not “soggy.”  The entire mass of plant waste should be moistened uniformly to the point where only a few drops of water can be squeezed from a fistful of plant material.

The microbes that break down plants use the plants for food.  Nitrogen is the most important nutrient.  A shortage of nitrogen in the composting materials greatly slows the process.  Green plant materials fortunately contain a high percentage of nitrogen.  Other sources of nitrogen include animal waste, granular fertilizer, or bloodmeal.  Carbon is also an important nutrient in the composting process.  Sources of carbon include woody materials, fallen leaves, shredded newspaper and animal bedding.
Smaller particle sizes greatly enhance the composting process.  Plant pieces of ½ to  1-1/2 inches are ideal, allowing sufficient surface area for microbial activity.  These different plant materials should be layered in the composting structure in 6-8 inch layers.  Use equal parts of green plant materials (nitrogen source) and dry plant materials (carbon source).  Some soil can be added to the compost pile to inoculate the pile, but research has shown that too much soil can hinder the composting process.  “Soilless” composting is an effective means of breaking down plant materials.

Thursday, November 12, 2015

Fall is here! A Re-cap of the Season from Colorado's Western Slope

Posted by: Susan Carter, Tri River Area Extension horticulture agent

Mr. Eggplant from the garden
Fall is here. Sometimes I wonder where times goes.  In review, it was a great long season on the western slope and particularly the Grand Valley for the garden.  The Master Gardeners in the Tri River Area installed a vegetable garden that kept on giving. We just removed the tomato plants on November 1st. Many vegetables were shared by staff and Master Gardeners, given to the Food Bank, and of course you could catch our Director out eating a tomato for a snack. The tomato viruses that plagued us in 2014 were much less in 2015. 

In the commercial trade, a better spring actually produced a cherry crop.  Peach thinning was assisted by frost, producing large juicy peaches this year. And apples were very abundant.  Only an area in Delta County had some losses due to cold. My personal Fuji tree   
Granny Smith apples
was so loaded, we had to install supports. I did not thin nearly enough, lesson learned.  My granny smiths were perfect, large crunchy tart apples. My husband also has a degree in Horticulture and took care of the frequent spraying for codling moth. If you have an apple tree, you have to do some kind of preventative spraying or the bugs will win and get the apples. There is a great Fact Sheet on apple care from CSU Extension.

We had several very successful festivals. If you live on the Front Range, come and visit the Lavender Festival, Peach Festival or Wine Festival. All three crops did well this year. 

We are watching some new insects that have arrived including the spotted wing drosophila, several aphids, one on Zelkova trees and one on wheat, and grape seed chalcid.

Pumpkins also did well on the western slope. My kids and I went to a local patch and came home with four different colors. We'll plant in spring for next year’s crop. There were minimal problems with the pumpkin crop. One was the weather was so warm close to Halloween, spoilage was a concern and the other main issue was powdery mildew from all the rain.  The spring rains also brought issues on some ornamental plants. Plants in the rose family like crabapples and ornamental pears had fire blight. Typically this issue is seen on the front range but not on the western slope.  We took the prune and wait method.  When is the weather ever the same year after year in Colorado?
Gorgeous pumpkins!

Monday, November 9, 2015

Frost and Freeze

Posted by Mary Small
Colorado State University Extension, Jefferson County
Jack Frost happens. Depending on the temperature and its duration, he can spell the end of the growing season for many herbaceous plants. I pondered the end as I went to look at the garden one morning following a frost. Instead of sighing in disgust I took delight in the magical beauty he left behind and that got me thinking more about frost.

Morning glory, still beautiful

We all know what it can do to plants. But what is frost, exactly? According to the National Oceanic and Atmospheric Administration, frost is the “formation of ice crystals on the ground or other surfaces in the form of scales, needles, feathers of fans.” Frost is common when the humidity is high enough, similar to the conditions under which dew is formed. (Dew forms, however, when temperatures are above freezing, not below.)

Frost alone doesn’t kill plants. That's why some can survive a visit from Jack and still look fine. Injury happens only when internal plant temperatures drop low enough so that ice crystals form inside plant cells. Cellular liquid freezes, forming the crystals. These sharp objects in turn, puncture cell membranes. As air and plant temperatures warm up, ice crystals liquefy. It leaks out of cells,dehydrating them. Voila! Dead, blackened, wilted-looking plants.

Frost crystals on a weed

 Plants growing close to the soil may survive freezing temperatures a bit longer than others due to warmth generated from the soil. This heat gets conducted up and around the plant at least a few inches. And get this...when soil’s moist, it can hold four times as much heat as a dry one and conduct it faster!

It's this soil warming we take advantage of when we cover tender plants, trying to avoid the inevitable. The heat gets trapped underneath the covering and keeps plants warmer than without it.

Next time Jack pays a visit, be sure to embrace the beauty he brings. After all, he's not to blame for plant death. He's just reducing the sting of season's end. 
 Frost on strawberries