CO-Horts Blog

Wednesday, October 29, 2014

Scenes from a Cemetery

Posted by: Alison O'Connor, Jane Rozum, Mary Small, Yvette Henson and Carol O'Meara

The five of us are attending the National Master Gardener Coordinator Conference in New Brunswick, New Jersey. To me, it's amazing how old everything is. In Colorado, "old" is 100 years. To those on the east coast, that's considered modern.

Our hotel is located across the street from two very old churches and adjoining cemeteries. In spirit with the Halloween season, we thought you'd enjoy some photos of what we saw (no ghosts or ghouls). It became obvious that maintaining the landscape within a centuries-old cemetery is a daunting task. The tombstones, some dating back to the early 1700s, are in various stages of toppling. The turf is old and thin. The mature trees create various challenges with surfacing roots and shading. But all in all, it was fantastic to walk through and see those who were buried in the graveyard. Many were soldiers of the Revolutionary or Civil War. In short: it was really, really cool!

Christ (Episcopal) Church cemetery in New Brunswick, NJ (ca. 1745)
First Reformed Church (Dutch Reformed Church) cemetery (ca. 1717)
One of the major problems with older cemeteries is surfacing tree roots.
Tree roots tend to grow on the surface in areas of low soil oxygen. This can
make maintenance around roots (and gravestones) difficult.
A very mature beech tree (love!) growing among dozens of graves.
I wonder if the tree root caused the headstone to lean?
Cemeteries are not exempt from piles of leaves
(it just adds another wrinkle to maintenance).
Turf, which competes for water with tree roots (and is often in very shaded areas), tends to look thin and weedy in older lawns (or cemeteries). Fine fescue is the dominant turf in older lawns, since it's the most shade tolerant grass species. Turf is difficult to maintain in cemeteries and sometimes plant growth regulators (PGRs) are used to reduce frequency of mowing, as maintenance around headstones is laborious.
Bugleweed (Ajuga reptans), a groundcover, has become
an attractive weed in this cemetery.
This is nimblewill (Muhlenbergia schreberi). It's a common warm season weedy grass, especially on the east coast and Midwest. It's difficult to control and forms dense patches in the lawn. It tends to be a problem in older, shady lawns
(or this cemetery). Being a warm season grass, it will turn brown with the first hard frost. It's often confused with bentgrass or bermudagrass. 
A praying mantis hanging out on a wrought iron fence.
What a gorgeous insect. 
Happy Halloween!

Monday, October 27, 2014

Ode to rabbitbrush, the late season jewel of the garden

Written by Marcia Weaber, Colorado Master Gardener and Native Plant Master, Pueblo County
Original article published in CSU Extension-Pueblo County newsletter, From the Ground Up.
Edited for Co-Horts blog and posted by Linda McMulkin.  Photos by L. McMulkin  

       Ericameria nauseosa (formerly called Chrysothamnus nauseosus) is a sub-shrub native of the western United States and Canada.  It is a member of the Asteraceae (sunflower) family and is known by a variety of common names, including Rubber rabbitbrush, Golden rabbitbrush, Chamisa, and Chamiso.  In southeastern Colorado it most commonly called Chamisa or rabbitbrush. 
Rabbitbrush flowers add color to the fall
landscape along I-25. 
That's Greenhorn Peak in the background.
         Rabbitbrush has narrow blue-gray to yellow-green leaves and flexible twigs that are covered with felt-like hairs that reduce transpiration and water loss.  Rabbitbrush is most happy growing in an arid landscape.  It prefers sunny sites, and is common where recent disturbance has occurred.  It is cold hardy and tolerates moderately salty soils.  Depending on the area, it will grow from 1-7 feet tall. 
     Contrary to its name, rabbitbrush is not eaten by rabbits, although they may use it for shade and shelter.  Deer, pronghorn, and cattle do not normally graze on it, but will if no other forage is available in the winter.
From August to October, rabbitbrush is covered with clusters of small golden yellow flowers that are attractive to butterflies, bees and other insects.  It is considered an important late season nectar source for native insect populations and should be part of any wildscape garden.  The shrub exudes an aromatic scent, especially noticeable after rainfall.   It sports fluffy seed clusters through the winter months, which add texture and interest to the garden.   
After the flowers fade, rabbitbrush
continues to add texture (and a food source)
to the gardens at Cattail Crossing
in Pueblo West.

Native rabbitbrush reproduces from seeds, which are distributed by the wind in the fall.  Germination occurs easily, but seedlings often do not survive without spring rainfall. Once established, rabbitbrush can survive easily on rainfall without supplemental watering.  Often, seedling establishment occurs near other shrubs where shading reduces moisture loss.
Dwarf blue rabbitbrush (Ericameria nauseosus var. nauseosus) was recommended as a Plant Select variety in 2011 and is available at nurseries throughout Colorado.  Colorado State University PlantTalk 1741 states, “As our urban landscape stretches towards the plains and into the foothills, the "borrowed view" of the surrounding areas includes native plants that are valuable additions to the home garden.” 

Rabbitbrush serves as a backdrop
for other xeric plants at
Kendrick Lake.
Rabbitbrush is touted as one of the most ornamental and useful native plants for a Colorado garden.  It is recommended to cut the plant back to about one foot in the early spring to help maintain the plant's natural globe shape and to keep the plant dense.

There are many companion plants that marry well in designs with rabbitbrush, including purple asters, Russian sage, winecups, California fuchsia, Agastache, and Blond Ambition grama grass.  It can also serve as a backdrop for spring and summer blooming perennials and native cactus.

Wednesday, October 22, 2014

The Glory of Pumpkins

Posted by: Jennifer Bousselot, Affiliate Faculty, CSU Department of Horticulture

To anyone interested in gardening, pumpkins are nearly synonymous with autumn. While the vines are easy to grow, they often have pest problems in Colorado. Therefore it is especially satisfying if you are lucky enough to get that bright orange fruit in the fall.
Miniature pumpkins at a local farmers' market
Saving seed from pumpkins is tempting but it is unlikely that you will get fruit next year that is the same cultivar. The reason is that insects pollinate the flowers on pumpkin vines. Pollen from other cucurbits (e.g. squash, cucumbers) that are flowering at the same time can fertilize those female flowers. If you are a brave gardener and try planting the seeds next spring, be prepared to see some strange formations on the vine! Often the spontaneous cucurbit combinations are not very tasty either. 

Most pumpkins and other winter squash mature between 90 and 120 days from planting. You can tell they are ripe when the rind thickens enough that you cannot easily puncture it with your fingernail. When harvesting, leave at least two inches of stem in order to maximize your storage capacity as shorter stems lead to dehydration and a brief shelf life. If the fruit is free of insect feeding or other damage it can last most of the winter in a cool, dark location that is around 70% humidity.
A plethora of winter squash (and pumpkins!)
In the next several days many pumpkins will be used for the higher purpose of jack-o-lanterns! After carving as desired, rinse the inside with a 10% bleach solution to slow the growth of decay fungi and allow to dry. Enjoy!

Monday, October 20, 2014

Forced fall bulbs provide winter color

Kathy Steffa
Colorado Master Gardener -- Chaffee County

My favorite fall bulb catalogs have arrived, and I am preparing my order of bulbs to grow indoors this winter. Two benefits of this are that I can grow tender varieties that wouldn't survive outside, and I don't have to worry about bad weather and sudden snowstorms.

The easiest bulbs to force are Paperwhite Narcissus which are usually grown in pebbles with water no higher than the bottom of the bulbs. Since I worry about overwatering and rotting the roots, I prefer to grow them in plastic pots with a mixture of half garden soil and half peat-based potting soil. The bulbs often arrive already growing, so I put them in bright light for three days until the shoots green up, then I move them to full but cool sun. Cool temperatures and regular rotation of the pots results in strong, straight stems.

All paperwhites are very strongly scented. The Chinese Sacred Lily has an orange cup; Grand Soleil d'Or is yellow and orange and should be grown in potting soil only as it takes longer to come into bloom.
The other bulb commonly forced in water is the Hyacinth, for which attractive eggcup-shaped glass vases are available. Carefully remove all the outer dry husk and add water to just below the bottom of the bulb. Do not put any fertilizer in the water.

Blooming is apt to be more successful if you purchase specially cooled bulbs. Otherwise, keep the vase in the dark at a very cool 50 degrees F. until the flower stalk is completely out of the bulb. Check the water level weekly and top off as it evaporates.

Amaryllis are another very easily forced bulb, and there are new varieties including Cybister hybrids and the Papilio "butterfly" which is green and maroon flowered. Both of these are evergreen houseplants and are never forced into dormancy by cutting off the leaves. Miniature hybrids, often not much shorter, and Trumpets have also been developed.

Christmas-flowering Amaryllis come into bloom earlier than the Dutch ones because they come from South Africa. They are supposed to have more leaves on the plant when it blooms so that the flower doesn't look so naked. Never remove dry, dead-looking roots from an amaryllis bulb as they do absorb nutrients until new roots form.

Almost as easy to grow as Paperwhites and Amaryllis are unfamiliar bulbs which do not require twelve to sixteen weeks of pre-chilling. I start these on the garage floor, covered with black plastic until I see some green growth. This has included Anemone blanda and A. coronaria, Dichelostemma, Dracunculus, Freesia, Ipheion uniflorum, Ixia, Ixiolerion, Lachenalia, Ornithogalum dubium (can't tell beforehand if they will be yellow or orange!), Pancratium maritimum, Ranunculus, Scilla peruviana, Sparaxis and Veltheimia bracteata. Calochortus and Fritillaria davisii and F. pudica have not been successful for me.

Once a green leaf shows, move the pots to a place in cool sun where the temperature ranges from 40 degrees F. at night up to about 60 degrees F. daytimes. (If the nights get cold enough to start freezing the soil in the pots, bring them in to a warmer place even if they aren't yet showing any growth.) They will grow slowly and bloom in two to four months. I fertilize them lightly with a diluted low-nitrogen and kelp powder mix at every watering and watch for aphids as the winter days lengthen and warm up.

When flowering is completed, Paperwhites are usually discarded. Hyacinths can be planted in a pot after bloomiing and saved until spring but will need two or three years of growth in the flowerbed to rebloom.

Keep watering the bulbs with the dilute fertilizer solution until the leaves dry up and save the bulbs in a cool place to replant next fall. Those hardy in Zones three and four can be planted outdoors for bloom next spring.

The ultimate indoor bulbs are garlic and Egyptian or walking onions. Let them grow eight to ten inches tall, then pull them up and chop into soup, salads and other foods for a touch of green at the winter table. Enjoy!

Websites of bulb companies include:,, and Alternatively, you can shop locally and mix-and-match the exact bulbs you want on a planting day convenient to you.

Monday, October 13, 2014

Ugh! Dealing with leaves in the fall

Posted by: Alison O’Connor, horticulture agent, Larimer County

It’s almost like nature mocks us. We work hard all summer to grow tomatoes, mow the lawn religiously and fend our garden from insects and disease. Just as we want to take a break and watch some college football (Go Rams!…and Cyclones…and Buckeyes), the trees decide to drop their leaves and landscape maintenance continues.

I’ve been asked this question a lot—What should I do with all the leaves that drop? There’s a lot of great ways to use them, including composting, tucking them around newly planted plants, throwing them in the veggie garden to till in next spring or mulching them into your lawn.

Wait…mulch them into your lawn? But doesn’t that cause thatch?
Sigh. So many leaves...
This is one of the great myths of urban horticulture—that mulching leaves (or grass clippings) causes thatch build-up. It doesn’t. Thatch is mostly comprised of living and dead turf roots, stems and shoots. It’s organic matter. And thatch only occurs on certain turf species—bluegrass and bentgrasses are thatch formers. Tall fescue and perennial ryegrass are not (they grow in clumps). Thatch will happen on bluegrass regardless if you collect your clippings or leaves. So mulch them in and reap the benefits.

Some fascinating research at Michigan State University has found that mulching fallen leaves into your lawn can decrease weeds and fertilizer use. Yes, you read that correctly: mulching leaves can decrease weeds in the lawn. The small leaf chunks fill in soil gaps in turf areas. These open soil spaces are perfect for weeds to germinate. In fact, MSU researchers found that after only three years of mulching leaves into the lawn, they found nearly 100% decrease in crabgrass and dandelions. That alone should convince you to mulch your leaves.
Mulch the leaves into the lawn. As long as you can still
see green grass, the layer isn't too thick. 
The fine Spartan researchers also found no effects on turf quality after mowing up to 6” of leaves at a time. They found the color, quality and density of the turf remained. And mulching leaves into the lawn resulted in quicker spring green-up because of a small fertility effect (most leaves contain 1-2% nitrogen). So over time, if you mulch your leaves faithfully (and your clippings), you will reduce fertilizer inputs to your lawn. Plus, the mulched leaves hold in soil moisture.

Here’s the key: set your mower height as high as possible and make sure that you can still see some green grass following mowing—you may have to make two passes over the lawn. If the leaf layer is too thick, it may not break down rapidly enough and can act like a mat on the turf surface. So mowing leaves frequently (once or twice a week) is best.

If you want to share the leaf love, consider bagging the leaves every so often and then use them for the other ways I mentioned above. If you planted new shrubs or perennials, circle a cage of chicken wire around the plants and fill in your leaf mixture. Or throw them in the garden. Leaves are the gardener’s gold. Enjoy your riches.

Tuesday, October 7, 2014

CSU “Best Of” Annuals for 2014

Posted by: Jim Klett, CSU Extension Horticulture Specialist

The Colorado State University Annual Flower Trials continued during the 2014 growing season with more than 1,026 entries from 26 different companies worldwide.  Initial evaluations were held on August 4, 2014 with close to 100 industry and advanced Master Gardeners participating.  A second evaluation was held on September 5, 2014 to make final decisions on our “Best Of’s” for 2014.  The winners include:

Best of Show  Dahlia ‘XXL Veracruz’ from Red Fox
Voted as “Best Dahlia” in 2013,’XXL Veracruz’ made it to the top as “Best Of Show” in 2014 with beautiful lavender and white bicolor flowers.  The stunning display of flowers was a perfect combination of color, large blooms and prolific flowering.  The “pom-pom” shape flowers had soft shades of lavender and white which would also make good cut flowers.  The vigorous plants maintained uniform growth and resisted lodging with strong stems throughout the season.
Dahlia XXL Veracruz
The lavender flowers of dahlia XXL Veracruz
Best New Variety –  Petunia ‘Supertunia® Black Cherry’ from Proven Winners
Plants had good vigor but the rich flower color was very captivating and brought it to the top as the “Best New Variety”.  The flowers had color shades that were very similar to a black cherry which made it very unique.  Plants had a tight mounding habit which made an impressive appearance covered in the abundant dark flowers.
Black Cherry Supertunia(R) flowers
Black Cherry Supertunia(R)
Best Novelty  Cuphea ‘Vermillionaire™’ from Proven Winners
The bright orange tubular flower made a great contrast against the dark green, glossy foliage for a unique combination of both color and texture.  The abundant small orange flowers gave a very delicate and showy appearance consistently throughout the growing season.  Plants not only took the summer heat but were much more resistant to flea beetles than traditional Cuphea.  It would work well in either the landscape or in containers and would be a good flower to attract hummingbirds.

Cuphea Vermillionaire habit
Cuphea Vermillionaire flowers
A complete list of all the 34 “Best Of” 2014 winners is listed on

Friday, October 3, 2014

Looking Beyond Tulips for Spring-Flowering Bulbs

Posted by: Alison O’Connor, Larimer County Extension

I love tulips, daffodils and hyacinth as much as the next person, but sometimes it’s nice to see a little more “bling” in the spring garden. As an FYI, if you haven’t been shopping at your local garden center, it’s BULB SEASON! I will muster the energy to plant some spring-blooming bulbs in the ground, simply because it’s really exciting to see them poke their noses out and add color to the brown mulch, brown turf and dormant (brown) trees in the March landscape.

So if you’re looking to add a few bulbs this fall, consider the following:

Gladiator allium from 
Alliums (Allium sp.): Ok, alliums (AKA ornamental onions) aren’t uncommon, but did you realize how many shapes, sizes and colors they come in? The Giant Onion (Allium giganteum) has flowers the size of softballs and comes in shades of purple, pink and white. While each bulb can be pricey, buying in bulk generally saves you some money. The great thing about planting “show and tell” bulbs is that you don’t need to plant en masse for a dramatic effect--one or two signature bulbs will do the trick. If you want smaller alliums to plant in groupings, consider species like A. sphaerocephalon or A. aflatunense.

Checkered lily
(photo from Missouri Botanic Garden)
Checkered Lily (Fritillaria meleagris): Have you ever seen a flower that has a checkered pattern? Seriously, really and truly checkered. I first learned about checkered lilies during my herbaceous plant class at Iowa State and immediately fell in love with this minor bulb. From far away, the plant looks like a drooping tulip, but up close, these small darlings have the most unique pattern. Colors range from deep purple to lavender to white. For the biggest impact, plant en masse with 5-10 bulbs per square foot.

Crown Imperial (Fritillaria imperalis): This is another species of fritillary, though much larger and makes a big statement with just one or two bulbs. Did I mention that fritillaries have a skunky smell—both the bulb and flower? While this may turn you off, it’s also important to know that deer and rodents tend to leave these bulbs alone once planted. The crown imperial is a fabulous bulb that produces a leafy stalk 3-4’ tall where a “crown” of bell-shaped flowers droop down. Flowers come in yellow, orange or red. I have one planted in my front yard and I’m always a bit taken aback when I’m doing spring chores and catch a whiff of the skunky flowers, but the beauty of this bulb makes up for that.
Crown imperial
(photo from
(photo from Michigan State University)
Snowdrop (Galanthus nivalis): The teeny tiny snowdrop is about the cutest minor bulb in the world. Growing just 3-4” tall (there are some cultivars that are larger) this bulb is truly the first sign of
spring since it’s one of the earliest to bloom. Snowdrops have been known to bloom in snow and also naturalize in the landscape. Each white flower has a dab of green on the three inner tepals, which are shorter than the longer, outer tepals. Plant up to 10 bulbs per square foot for maximum impact.

Summer Snowflake (Leucojum aestivum): Don’t let the common name fool you, since this minor bulb blooms from April to May (but it does bloom later than spring snowflake, L. vernum). The snowflake bulbs look very similar to snowdrops, but they have a green dot on each of the tepals, which are equal in length. The nodding flower is bell-shaped and sits on top of a leafless flower stalk (scape). Plant en masse for the greatest effect with at least 10 bulbs per square foot.
(photo from Erin Mahaney, University of California)
And there are plenty of unique-looking tulips, daffodils, hyacinth and crocus available as well. Some have frilly flowers; others are two-toned. If you’re shopping for bulbs, keep the following in mind:

  1. If you have the option, pick out individual bulbs to plant. Select ones that are large, firm and free from disease or rot. Be sure to label your bags or pick up the plant tags for each species.
  2. Plant bulbs before cold weather sets in. In general, it’s best to plant spring-blooming bulbs by mid-October. If planted too late, it may affect bloom and establishment.
  3. Plant bulbs with the roots down and the pointy tip up. Not sure what end is down? Then plant the bulb on its side—it will figure it out. Bulbs should be planted 3-4 times deep as the length of the bulb. For example, if a bulb is 2” long, it should be planted 6-8” deep.
  4. Unless you’re planting en masse, follow the spacing suggested on the plant tag. If planting for optimal effect, spacing can be greatly reduced.
  5. Water your bulbs well after planting and mulch. The need for bulb fertilizer seems to be debated, but if your soil lacks nutrients, adding fertilizer won’t hurt.
  6. Mulch over the tops of the bulbs with a 2-4” layer of organic mulch.
Do you have a specific bulb species or cultivar that you love? Leave us a message…and be sure to include your approximate location (whether in Colorado or the great beyond).