Category Archives: Uncategorized

CSU Denver Extension Plant Sale Fundraiser!

plant saleCSU Denver Extension will be having a no contact and social distance plant sale fundraiser for May 21st and 22nd!

We are excited to offer up some of our favorite varieties of sweet and hot peppers for $6 a plant. To learn more about the varieties of peppers available and to order your plants please visit our website: https://denver.extension.colostate.edu/…/csu-denver-plant-…/

All the money raised from the plant sale and donations goes to support the Denver Extension office.

We look forward to seeing you soon and thank you for supporting our office and programs!

Murder Hornet: Reality for Coloradoans

murder-hornets-with-sting-that-can-kill-land-in-us

Image via Kenpei/Wikimedia Commons

Recently a report on the discovery of the large, native Asian hornet (Vespa mandarinia) in Washington state and British Columbia went viral. The New York Times dubbed it the “murder hornet” because of its striking appearance and size (about 2″ in length, wingspan of 3″), assumed threat to the honeybee population and quarter inch stinger to inject venom into humans.

Dr. Whitney Cranshaw, Colorado State University’s Entomologist and Extension Specialist, offers a constructive look at the Asian hornet and cautions us to look past the dramatic, attention-grabbing headlines.

Cranshaw notes the following:

  • Traps and controls have been developed in Asia and can be adapted for use in the very small outbreak in Washington and British Columbia.
  • While some insects relocate to new areas via packing materials, wood or other carriers, this hornet does not hitchhike well. Given that, to reach Colorado, it would need to navigate difficult terrain from Washington. This is considered unlikely.
  • The insect is a woodland species which lives in low altitude, moist environments. It is not likely to thrive or adapt to the semi-arid Rocky Mountain region. If it did get transported here, it is doubtful it would survive.
  • It is a generalist predator and honeybees are just one of its many predatory targets. Whether the giant Asian hornet will pose any greater threat to honeybees than existing predators remains to be seen. But it is possible that colonies in the wasp’s preferred woodland areas could be the most vulnerable honeybees.

Cranshaw and other entomologists caution that “Murder wasp” is an unwarranted, fear-inducing name. While imposing and unique for its appearance, the Asian hornet’s potential impact needs to be kept in perspective and is not expected to live up to the recent hype.

Additional Resources:

USDA New Pest Response Guidelines

“What’s In A Name? CSU Entomologist Says Title is All Buzz, No Sting”  KUNC Radio Interview with Dr. W. Cranshaw, May 12,2020

Written by Linda McDonnell, a Denver County Master Gardener

 

Container Vegetable Gardening

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Colorado State University

Want to grow vegetables but have limited outdoor space or no “dirt” of your own?  Like the ease of growing in pots versus in the ground? Sounds like container gardening is made for you. Here are some helpful tips for successful gardening in pots.

What to Plant

Peppers, squash, greens, potatoes, basil are among the many plants that grow well in containers – check this Planttalk Colorado publication for details and inspiration. When purchasing plants or seeds, look for cultivars described as compact, dwarf, patio or bush. Determinate tomato varieties work well but I also have great success with ‘Sun Gold’, a sweet, prolific indeterminate cherry tomato. (Determinate varieties tend to ripen all at once while and grow on bushier plants, while indeterminate ripen over a longer period and tend to be larger plants.)

Where and When to Plant

Generally, vegetables and herbs need 6-8 hours of sun a day. Placing your container on a strong dolly with wheels allows you to move the plant to find the ideal space. A dolly also helps you quickly shelter your plants from Colorado’s wicked summer hailstorms.

Warm season vegetables such as tomatoes should be planted when evening low temperatures are consistently above 55 degrees. Don’t rush things – in Denver, this generally means late May, even though Mother’s Day weekend is touted as the kickoff to the gardening season.

What Container to Use

squash

Colorado State University

The larger the plant, the larger the root system.  Salad greens successfully grow in pots that are 6-12” deep and at least 18” wide, while a tomato needs at least a depth and width of 14-16″ or more. Larger pots are less prone to drying out rapidly and because they hold more growing medium, the plant receives more nutrients and has plenty of room for root development. Generously sized, heavy containers anchor large plants in the wind and will help avoid tipping and broken branches.

Plastic, glazed or unglazed clay pots or wood whiskey barrels are popular choices. Unglazed clay pots can require more frequent watering, especially in the hottest part of the season. No matter what your container is made of, it must have good drainage holes.

Don’t forget to add support for vining or large plants – stake, cage or trellis your plant just as you would if it was in the ground. These plant aides are easiest to add before the plant needs it. Wrestling a metal cage over a sprawling plant is not fun and may not be successful. I’ve tried.

Soil and Fertilizer

Use potting media specifically for containers and/or vegetables, often labeled soilless.  “Soilless” potting soil sounds like an oxymoron, doesn’t it?  Just like traditional potting soils, it can contain peat moss for nutrients, vermiculite for water retention and perlite to aide in air movement around the roots. The mixture will weigh less and is good to use in heavy containers.

Container veggies grow vigorously and therefore require lots of nutrients. Some mixtures contain time release fertilizers, which help plants get off to a good start, but will not feed plants for the entire season. Excellent information on using soluble and time-release supplements  in our region can be found here.

Penn State Extension noted that time release fertilizers release nutrients faster in warm weather; a pellet fertilizer labeled to last 4-5 months will only last 2 months if the temperatures are above 85 degrees.

According to Colorado State University, “Organic fertilizers such as fish emulsion or blood meal can also be used if desired but may be available too slowly for actively growing plants or may develop sour aromas that attract pets and pests.”

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Parker County Texas Master Gardeners

I’ve always added gravel or broken clay shards to the bottom of  pots for drainage.  Turns out, it’s not necessary or even advisable. Studies by Washington State University and others found that a layer of inorganic material drives excess moisture up to the roots rather than helping with drainage.  Excess moisture suffocates roots and reduces oxygen flow.  So, this year, I’m simply covering the drainage holes with pieces of metal screen to keep soil from leeching out. Paper coffee filters can do the trick too.

When to Water

There is no one-size-fits-all answer to this often-asked question. A best practice is to check plants daily, ideally in the morning. Poke your finger into the soil, if it is starting to dry out at your first knuckle, water at the soil line till water flows out the bottom of the pot. Consider factors such as temperature, wind, reflective heat from surrounding hard surfaces, and as mentioned earlier, the type of container used. In the heat of the summer, you will likely water every day, possibly twice.

Do not allow vegetables to dry out completely – they may not forgive you!  Results of underwatering can include deformed  fruit, poor growth, disease or even loss of the plant.

Conclusion

So there you have it, a round up of solid research-based advice for container gardening. Growing edible plants in pots is rewarding and can yield excellent results. It’s a reliable method for experienced and beginning gardeners alike.  If you’ve never given it a try, its a fun summer activity which can provide plenty of healthy, tasty rewards.

 

Written by Linda McDonnell, Denver County Master Gardener

CSU Extension Spring Gardening Webinars

Free-Classes

Click here for the updated list of CSU Extension Spring Gardening Webinars!

These classes are FREE for the public.
(All Zoom classes have a 300 person limit- 1st come first serve)

Upcoming Topics include:

  • Vegetable Varieties for the Garden
  • Pollinator Paradise: How to Attract Them to Your Landscape
  • Waterwise Landscape Design

Keep checking back for additional classes that are being added!

 

Merrill Kingsbury, Master Gardener Program Assistant, CSU Denver Extension

Grow and Give-A Modern Victory Garden Project Website

Grow and Give

Check out this new website from the Colorado Master Gardener Program!  Learn to grow food and donate extra locally. These resources are designed to help you grow your own food this year and beyond. Colorado State University Extension & Master Gardeners are here to help you! Click here to view the website!

This site is being continually updated with new videos, linked fact sheets and information about how to grow your own food at home in Colorado.

Check out a sample of the many videos on the website:

By Merrill Kingsbury, Master Gardener Program Assistant, CSU Denver Extension

 

 

 

Growing Hops in the Home Garden

Growing hops at home for brewing or ornamental purposes can be quite rewarding.  However, consistently producing healthy hop plants with good cone yields is a bit of an art, but with experience, it is a process that can be mastered by following a few easy steps.

Hops (Humulus lupulus) is a perennial in the hemp family (Cannabaceae) that produces annual bines from overwintering rootstock.  Hops are native to Europe, western Asia, and North America and are one of the key bittering and flavoring ingredients of beer.

Hops are described as “bines” rather than “vines” because they climb by wrapping around a supporting structure in a clockwise direction and cling to the surface using stiff downward-facing hairs.

Hop plants are dioecious; they have separate male and female plants. Only the female plant produces the cones and lupulin utilized in brewing.  Lupulin is a yellow, resinous substance produced by specialized glands within the cones. Lupulin contains the oils and resins that give hops their distinct aroma. Hops are rhizomes that have underground stems that can produce additional roots and shoots.

Step 1. Selection and Propagation

Cascade, Chinook, Nugget and CTZ varieties will grow well on the Colorado Front Range.  Nugget and Chinook varieties are prolific growers and are very resistant to both insect pressure and diseases.  Rhizomes can be purchased from some homebrew stores, through mail order from many growers, or by propagating established plants.

In Colorado, rhizomes should be divided in late February to early March while plants are dormant. If possible, untrained bines should be coiled around the base of the plant during the growing season and covered with soil. The covered bines will convert to rhizomes, which can be removed in the winter by digging adjacent to the plant and cutting the rhizomes from the plant using a sharp, sterile knife. Ideally, cut the rhizomes into approximately 3-inch lengths with multiple buds.

Stem cuttings can be taken throughout the growing season but are more likely to root when obtained in the spring through early summer before flowering. Several cuttings can be taken from one bine. Dissect the bine so that each cutting has one node at the top, dip the stem bottom in a root toner, and place the cuttings in sand or florist’s fam. Keep the rooting media wet, and roots should develop within 2 weeks. Once roots are well formed, transplant the cutting into a pot with soil and fertilize with a basic fertilizer such as 16-16-16.

Step 2. Establishment and Care

Hop bines normally grow from 15 to 20 feet high but may grow higher depending on the climate and available climbing support. They require full sun (12 hours), good air circulation and well-drained soil with a pH between 6 and 7.5 for high productivity.  A large container such as a half whiskey barrel can also be used and allows you to manage your soil conditions and help keep any unwanted spreading of the rhizomes into your yard.

Once the threat of a killing frost has passed in the spring, transplant the hops into the desired outdoor site. Dig a narrow trench 12 inches deep and slightly longer than the rhizome. Plant one rhizome per hill with the buds pointed up and over with 1 inch of loose soil. They should be spaced three feet apart. Initially, provide consistent watering while being careful to not over water because hops do not like to have “wet feet”.

After establishment, provide climbing support such as a pole or trellis at the planting site. Ideally, string a top wire about 15 to 18 feet high, then attach strings the hops will climb. As an alternative, erect a single pole, which is what most commercial yards did until well into the nineteenth century, and run strings to the top.  The string needs to support plants that will weigh 20 lbs when mature.  If planting two or more hop plants side by side, allow 24 to 36 inches of spacing between plants. If growing for ornamental reasons, a standard trellis or arbor can also work and keep bines pruned to keep desired form. The cones will grow on sidearms as the plant grows.

The focus in the first year of planting is root establishment and not cone production, thus it may be beneficial to limit the plant’s ability to climb during establishment by supplying only a 4-foot stake or pole. Be careful not to remove foliage during the first year because the plants require as much leaf material as possible to develop and store carbohydrates in the root system for the following year’s growth. Plants usually reach full production in their second or third growing season.

Step 3. Train the Bines

As the shoots grow to approximately 3 feet in length, choose the 2-3 most vigorous to grow and remove all remaining shoots. As the shoots elongate, train them onto the support structure by winding them in a clockwise direction, which follows their natural growth habit. Plants may be fertilized during spring and early summer, but fertilizer is not typically required after mid-July. Nitrogen is usually the limiting nutrient for adequate hop growth. You can apply nitrogen as urea (46-0-0) or in combination with other nutrients such as a 16-16-16 fertilizer.

Step 4. Irrigation

Hop plants require consistent moisture throughout the growing season. The plant roots want to be wet but not waterlogged. You may let the soil dry out slightly between waterings. Hop plants grow very rapidly during the heat of summer, so it is important to deliver consistent, even moisture to prevent drought stress. A hop plant may require several gallons of water per day during the summer. Water at the base of the plant to minimize wet foliage which can lead to disease issue.

Step 5. Common Diseases and Insects

Powdery mildew is a common disease affecting hops in our climate.  It is caused by the fungus Podosphaera macularis.  Although unsightly on the foliage, powdery mildew is most problematic when it attacks developing cones during the summer. Cone tissue infected with powdery mildew becomes necrotic and deformed, and chemical composition may be negatively affected. Control measures include spring pruning to remove infected tissue and fungicide application with products such as sulfur.  Many varieties of hops, such as Nugget or Chinook are resistant to the disease.

Spider mites are a common insect problem. A minor infestation causes bronze leaves, while a severe one results in defoliation and white webs. Spider mites are most dangerous during warm dry weather and not usually a problem for well-watered plants.

Step 6. Harvesting and Storage

Hops typically mature between mid-August and mid-September. Hop cones harvested for beer brewing can be used fresh after picking, or dried and sealed in an airtight container in the freezer for later use. Mature cones will have a dry, papery feel, and the lupulin inside of the cone will be golden yellow and have a pleasant “hoppy” aroma. Immature cones will feel soft and vegetative, and the lupulin will be pale yellow with a mild vegetative aroma.

After harvest, cut the bines off the trellis leaving 2 feet of bine above ground.  Do not cut down the last green matter until after the first frost, then prune bines to a few inches and cover with mulch.

Sources:

Hieronymus, S. (2012). For the love of hops: the practical guide to aroma, bitterness and the culture of hops. Boulder (Colorado): Brewers Publications.

Growing Hops in the Home Garden: https://catalog.extension.oregonstate.edu/em9115

Powdery Mildew Fact Sheet: https://extension.colostate.edu/topic-areas/yard-garden/powdery-mildews-2-902/

Aphids on Shade Trees and Ornamentals: https://extension.colostate.edu/topic-areas/insects/aphids-on-shade-trees-and-ornamentals-5-511/

Spider Mites: https://extension.colostate.edu/topic-areas/insects/spider-mites-5-507/

Organic Hops Variety Trials and Over-wintering Study: https://specialtycrops.agsci.colostate.edu/organic-hops-variety-trials-and-over-wintering-study/

 

Written by Kevin Ritter, a Denver County Master Gardener as well as Crooked Stave Artisan Beer Project’s Laboratory Technician and Sensory Specialist.

Photos courtesy of Pixabay.com, a source for royalty free images

Meet the Garden Squad—Gardening Help at the Denver Botanic Gardens

Meet the Garden Squad is a way to get better acquainted with some of our CSU Extension Master Gardener volunteers.

Meet the Gardening Help Volunteers

The CSU Extension Master Gardeners usually pick up the gardening helpline at the Denver Botanic Gardens or answer questions when people walk-in the door. Even though buildings at DBG are closed for now, gardeners can still get their gardening questions answered by Gardening Help from Colorado Master Gardeners at Denver Botanic Gardens, only remotely.

The interest in gardening has soared ever since people have had to hunker down at home and find ways to keep busy. First-time gardeners will likely have questions on how to get started, what to plant now, what can grow in containers, and much more.

Even gardeners with some experience have questions, too. All gardening questions can be emailed to gardeninghelp@botanicgardens.org and a CMG, working remotely, will reply by email.

Gardening Help volunteers include: Back row, left to right: Jan Fahs, Jan Davis, Ken Zwenger, Mark Zammuto, Gordon Carruth, Fran Hogan
Middle row: Lynne Conroy, Harriet Palmer Willis, Kathleen Schroeder, Leona Berger, Cindy Hanna, Mary Adams, Nancy Downs
Kneeling: Dee Becker, Charlotte Aycrigg, Jan Moran
Not pictured: Mary Carnegie, Linda Hanna, Maggie Haskett, April Montgomery, Ann Moore, Kathy Roth, Amy White

Gardening Help is a project of the CSU Extension-Denver Master Gardeners at the DBG. Volunteers provide reliable and research-based information to thousands of home gardeners each year.

Volunteers commit to at least one year in the role, with a minimum of six shifts spread across the year. The commitment starts early in the year with an orientation and training from Nancy Downs, project coordinator.

Many volunteers are GH regulars and they return to the project every year. In addition to being an active CMG, they have to satisfy DBG volunteer requirements, too. That means they’re a member of the DBG and enrolled there as a volunteer.

Some of the key characteristics of GH volunteers are good research, plant identification and diagnostic skills. Because the project is located at DBG, volunteers need to keep on top of what’s blooming at the DBG by season, so they can answer common questions that might pop up.

Photo provided by Nancy Downs

Text by Jodi Torpey
Master Gardener volunteer since 2005

Poinsettia Challenge – Steps for Reblooming

plant-185709_1280It’s January and the holidays are behind us, but if you can’t bring yourself to toss your poinsettia plant, why not try to coax it into reblooming next December? It takes basic indoor plant care skills, perseverance and some properly timed steps to insure flowering.  Here are season-by-season instructions for success.

Winter: Protect the plant from cold and drafts, with daytime temperatures of 67-70 degrees, nighttime temperatures of 60-62 degrees. To maintain healthy foliage, fertilize monthly following balanced houseplant fertilizer directions, water when the soil is dry below the surface but not soggy.  Avoid “wet feet” by draining excess water from the plant saucer.

Watch for mealy bugs (cottony puffs), which can be easily removed with a cotton swab dipped in rubbing alcohol.

ec001cosSpring: By late March or early April the plant will look tired – it’ll most likely have dried, yellowed or fallen leaves. You’ll be tempted to put the plant out of its misery at this point!Instead, remove the bracts and part of the stem, ideally leaving 3-4 leaves on each stem. This pruning can be done anytime through mid-July.

Late spring/early summer: Repot the plant in a pot that is one size larger (approximately 1-2” inch larger in diameter). Use a quality, well-drained potting mixture, fortified with 1 tablespoon super phosphate (0-46-0) per gallon of soil mix. Slow-release fertilizer applied to the soil surface is also beneficial if the soil mix does not already include fertilizer.

Summer: When outdoor temperatures are consistently above 60 degrees, the plant can live outdoors in a shaded area such as a porch.

It will be putting on a lot of growth during this time and should be pruned about every six weeks to promote side branching and good form. Stop pruning in late August.

Late Summer: If the plant has been outdoors, you’ll want to bring it in around Labor Day or when nighttime temperatures drop below 55 degrees. Place it in a sunny or bright location with temperatures of 65-75 degrees. Continue monthly fertilizing.

ec002cosFall: Poinsettias require 8-10 weeks of shortened days to stimulate flowering. Starting the first week of October, put the plant in complete darkness for about 15 hours a day -ideally 5pm-8am.

It can be covered with a big box, put in a closet or sequestered in a room with no light at all.  Longer, completely dark nights and bright, shorter days are the key to successful reblooming. This step is non-negotiable.

Around Thanksgiving, colored bracts should appear. This is the sign to stop the dark treatment, continue fertilizing to promote blooms and keep in a warm, bright spot in your home and enjoy your holiday plant!

I have a big, beautiful poinsettia, have set my calendar reminders and am ready to give this a try.  How bout you?

Additional reading:

https://extension.colostate.edu/topic-areas/yard-garden/poinsettias-7-412/

https://extension.unh.edu/resource/poinsettias-care-and-reflowering-fact-sheet

Photo: Pixabay.com

Drawings: Colorado State University

Written by Linda McDonnell, a Denver County Master Gardener

Test Your Poinsettia IQ

poinsettia-458762_960_720Poinsettias (Euphorbia pulcherrima) are making their December debut this week. With up to 50 million plants sold annually, you are likely to give,  receive, or at the very least, encounter the plant in your daily travels this holiday season.

How much do you know about the care and history of this botanical holiday plant?

True or False? Poinsettias are highly poisonous – keep children and pets away.

Mostly false. According to the University of Illinois Extension, “A study at Ohio State University showed that a 50-pound child would have to eat more than a pound-and-a-quarter of Poinsettia leaves (500 to 600 leaves) to have any side effects. The leaves are reportedly not very tasty, so it’s highly unlikely that kids or even pets would be able to eat that many!” So, while ingestion can cause mild stomach irritation the plant is not considered highly toxic.

True or False?  The plant was brought to the U.S. in 1915 by a shopkeeper as a gift for parents who brought their children to breakfast with Santa.

False. Robert Pointset, a botanist, physician and first U.S. Ambassador to Mexico is credited with bringing the plant to the U.S. in 1848, when they were introduced at the Philadelphia Flower Show.

True or False? For longest enjoyment, select plants with tight oval bead-shaped structures, which are the actual flowers that surround the colored leaves or bracts.

True. The colored bracts, or modified leaves (commonly, but incorrectly referred to as the flower) will start to fade when the center cyathia  (flower) open and release pollen. Look for tight, spikey bead-shaped buds when selecting plants.

True or False? The Aztecs used the colorful parts of the Poinsettia to make a reddish-purple dye for clothing and believed the sap cured fevers.

True. Poinsettias were used for practical and ethnobotanical uses in ancient cultures, including coloring cloth and treating fevers.

True or False:  National Poinsettia day is October 1st, the day that plants should start receiving 12-14 hours of complete darkness in order to rebloom. 

Partially true. October 1st is the date to start giving your Poinsettia half days of complete darkness, called photoperiodism, to trigger reblooming.  But if you want to celebrate Poinsettia day (and who doesn’t?)  it is December 12th, the day Robert Poinsett died in 1851.

True or False: Poinsettias come in over 100 natural colors. 

True. Local garden centers have lots of red, pink, cream and coral varieties along with some sassy lime green, orangey-yellow cultivars and splotchy multi-colored bracts.  Mother Nature has no hand in producing the Bronco blue and sparkly grape colored varieties – these are sprayed and glittered.  There’s a poinsettia for every taste!

True or False: Allow a Poinsettia in bloom to dry out completely before watering.  

False. Poinsettias can be divas — water when soil surface is just dry to the touch so check daily, especially if the plant is in a small pot.  Leaves will droop and yellow if the plant gets too dry. Don’t let the plant sit in water and keep it away from cold and drafts. Ideal temperature is between 65-70 degrees and there is no need to fertilize when in bloom.

Which is the correct pronunciation Poin-set-ah  or Poin-set-ee-ah?

Either way is correct!

Check back next month for tips on coaxing your poinsettia to bloom next year. It’s a good challenge for indoor plant collectors.

Written by Linda McDonnell, a Denver County Master Gardener
Photo courtesy of Pixabay,  a source for royalty free photography

 

The Weather Outside is About to Change

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October is the month the garden takes its final breath, the first frost arrives (this week!) and pumpkin-everything surrounds us. We’ll still have some beautiful fall days, but there’s no denying it, the growing season is coming to a close. So with that in mind, here’s a round up of helpful information for the days, weeks and months ahead.

  • Sometimes working less is working smarter – find tips for putting the garden to bed here and here.
  • Why am I always late scheduling this? Instructions for winterizing sprinkler systems here. (It’s helpful to read even if you leave this task to others.)
  • Have your houseplants been living outdoors? With temperatures about to plunge, it’s time that vacation comes to an end. Some good reminders on how to help them transition to lower light can be found here. 
  • My Chanticleer Pear tree (Pyrus calleryana ) is soooo prone to storm damage in both the fall and the spring – this CSU PlantTalk article provides excellent information on snow-load damage and pruning of herbaceous plants.
  • If you have upright junipers, you know they are also prone to winter splitting. Here are some excellent tips on preventing structural damage, including a creative use for Christmas lights.
  • And finally, be mindful of the winter moisture levels. “Your Yard is Thirsty” offers advice on winter watering of a variety of plants.

Written by Linda McDonnell, a Denver County Master Gardener

Image by Anne Hughes, a Denver County Master Gardener