CO-Horts Blog

Thursday, July 25, 2013

Heaven and Hail

By Darrin Parmenter, CSU Extension-La Plata County
Posted 7-25-13

Oh hail, no.

We here in arid southwest Colorado typically don’t see hail, or hail damage, like our brethren over on the Front Range. Our days are typically filled with plenty of sunshine through the day, a monsoonal rain shower in the late afternoon to cool things down, rainbows over the mountains, and even unicorns. Yes, it is a dreamland of epic proportions where everybody smiles and streams of lemonade come trickling down the rocks.

Hail damage on immature apples.
Until the day, when on a relatively rare occasion, it hails. According to the National Severe Storms Laboratory, hail is a type of precipitation that forms when updrafts in thunderstorms carry drops of rain back up into colder areas of the atmosphere, where they freeze into balls of ice. These projectiles have violent collisions with supercooled water droplets, increasing the size of the hail stone. If the updrafts are strong enough, the hail continues to be pushed towards the tops of the clouds until at some point the air cannot support the weight of the stones and they come crashing down – at speeds estimated near 100 mph – to earth.

So as science geeks, this is an incredible process. But if you have trees, or vegetables, or a car, hail is typically not a welcomed form of precipitation. Two weeks ago a powerful system moved through our area, dropping hail from the Hesperus area eastward through Ignacio and even into western Archuleta County. Localized hail caused significant damage to a number of gardens and farms. If your landscape has been hit by one of these storms, here are some suggestions:

  • Your squash and cucumber plants are going to look awful. The large, fragile leaves could be shredded. But fortunately, cucurbits are fast growers that they typically recover relatively quickly.

  • Leafy crops may also be shredded. Try to remove all damaged leaves and hopefully the plant will regenerate new growth.

  • Fruit, such as apples or pears, may incur damage in the forms of pitted fruit. This fruit is not marketable and if it does survive will almost always be scarred.

  • Most plants will respond favorably to a light application of nitrogen and some micronutrients after the hail event.

Monday, July 22, 2013

Selective Mowing: Part Of My Minimalist Gardening Strategy

By Linda McMulkin, CSU Extension-Pueblo County
Posted 7-22-13

I’ve been accused of being a lazy gardener, but I actually do have a strategy.  My goal is to spend as little time fussing as possible.  Plants that live in my yard better be able to fend for themselves, as irrigation is rare and fertilization and deadheading just don’t happen.  My friend who has a similar attitude toward garden maintenance calls us minimalists, a term I like much better than lazy.

This flag helps me remember the location
of a prickly pear nestled in a patch of
shaded red three awn.

My home sits on a flat, skinny urban lot with clayey soil and no irrigation system.    We have trees, shrubs, and herbaceous perennials (a mix of native and non-native) and a buffalo grass lawn close to the house, but the back 2/3 of our lot is a haven for native prairie plants.  I have several types of native grass, each growing on the section of the property that provides their favorite mix of sun and shade.   About 20 species of native forbs live with the grasses, some more prolific than others.  This spring, even with the drought in southeastern Colorado, I had a carpet of native verbena that took my breath away.

I mowed some of the Kochia but have many to hand pull this week. 
At least I'll have some pretty plants to keep me company.

This patch of hairy golden aster
welcomes me home  every day.  My neighbors
are letting this plant grow in front
of their houses as well.

My prairie restoration project requires that I let desirable plant species go to seed while hand pulling weeds.  Mowing is a challenge, since I’ve let the plants tell me where they want to grow rather than in defined beds.  They are scattered inconveniently for a push mower.  Sphearalcea grows with Oonopis near the pines, prickly pear is mixed with red three awn, winterfat has been left to thrive in every dry spot, and the occasional patch of Indian rice grass is celebrated wherever it wants to grow. I’ve developed a strategy called “selective mowing” with the goal of cutting back desired species that have completed seed production or are looking ratty, plus thwarting annual weeds that I haven’t pulled yet.  The result is a shaggy mix of groomed and ungroomed landscape that makes my neighbor with a riding mower shake his head in puzzlement.

Mowed buffalo grass with a swath of unmowed blue grama. 
Yes, I'm aware of the weedy species mixed in. 
That is next weekend's project.

Yesterday I mowed the buffalo grass, but left patches of blue grama to set seed.  I mowed Kochia in some spots, but left the weeds mixed in with a big patch of Sphearalcea and Oonopis (I promise to pull weeds in the evening this week).  I removed the tops of spent Aristida purpurea in the sun, but didn’t mow the newly blooming section in the shade near the fence.  And I circled around one patch of verbena that looks like it may bloom again after the recent rain.

Selective mowing requires knowledge of the plants in my yard plus the patience to stop and plan where to push the mower next.  I also find that a bit of ruthlessness helps.  I had to remove one lovely Schearalcea yesterday in order to reach a patch of Kochia, but I left 10 plants alone, so there is plenty of seed still to come.

The pay off of letting the prairie plants pick their spots is that I irrigate only monthly with a hose-end sprinkler, mow about 4 times a year, provide food for lots of quail and bunnies, and get to enjoy the native landscape without leaving my deck.  Does that make me lazy?  Minimalist works for me and I’ll continue to encourage those plants that let me sit on the deck and not stress about landscape maintenance. Okay, maybe a little lazy…..

Sunday, July 21, 2013

Banish Those Mid-Summer Gardening Blues

Posted by: Micaela Truslove, Broomfield County Extension

Late July is a tough time in the garden.  It’s warm--really warm--and the beautiful little transplants and seedlings you had in June are now beginning to show their age, while the weeds and insects seem to be growing stronger and more plentiful by the day.  It’s enough to make any gardener frustrated, but before you throw in the trowel and give your garden over to the beasties, let’s step back and talk about some tools that will get you through the long, hot mid-summer days, sanity intact.

Deadheading can result in
beautiful bouquets for your
home. (Photo M. Truslove)
Provide the right environment to keep plants healthy.  The first step to give plants a fighting chance is to make sure they have everything they need to remain strong in the face of mid-summer challenges.  When plants are run-down and weak, they are far more susceptible to disease organisms and insects, just like us (well, minus the insect bit).

Practice smart watering.  Making sure plants have adequate water is obviously important when temperatures begin to rise, but avoid the “more is better” approach.  Soggy soils can be just as harmful as dry soils.  Remember that ideally plants need equal parts oxygen and water in the soil to grow properly. Proper watering rather than overwatering will help keep plants hydrated and happy.

It’s never too late to mulch.  One way to conserve water and ensure even soil moisture is to mulch.  At a recent talk about caring for woody plants during drought, Fort Collins City Forester Tim Buchanan said “Good things happen to people who mulch”.  Mulching is important for many reasons, including keeping plants cool and hydrated.  Even if you applied mulch in the spring, now is a good time to make sure you still have good coverage.  Three to four inches is generally adequate.  Apply and wait for good fortune to befall you.

Fertilize wisely.  Avoid the temptation to douse ailing plants with a heavy dose of fertilizer. Some plants, such as annuals and those kept in containers, may benefit from a light application of water soluble fertilizer.  They often start losing steam mid-summer because the nitrogen reserves in the soil have been depleted.   Some vegetables are heavy feeders, such as corn and potatoes, and also benefit from a small boost of fertilizer later in the season.  A good sign that they are low in nitrogen is that the leaves begin to yellow, starting with older leaves at the base of the plant.  Remember that nitrogen promotes leafy growth over flower and fruit production, so avoid excessive applications of N late in the summer.

Avoid the temptation to fertilize perennials this late in the game. These plants are past the initial growth spurt that naturally happens earlier in spring and summer and are winding down for the year. Fertilizing late in the season encourages succulent new growth that will be vulnerable to insect attack and cold injury in winter.

Remove plants that are past their prime.  Sometimes tough love is the best love.  This goes for annuals and vegetables that are limping along so you can glean one last harvest or one final bloom.
These new beet seedlings will
be ready to harvest by fall.
(Photo: M. Truslove)

These plants are magnets for pests and diseases, so remove them, add them to the compost, and know that their death hasn’t been in vain.  Replace them with fresh, new plants, or in the case of vegetables, plant a second crop for a fall harvest.  In the Denver metro area we still have roughly 70 days until the first average frost, so choose crops and varieties that will mature before the first week of October.  Good candidates are leafy greens such as spinach, swiss chard and lettuce, beets, carrots, turnips, broccoli, radishes, and peas. Be sure to check seed packets as different varieties of the same vegetables can have wildly different maturity rates.

Deadheading.  Also in the category of tough love is the practice of deadheading.  Yup, sometimes plant decapitation is just what the doctor ordered.  By deadheading, you are thwarting the plant’s mission to reproduce, so it keeps making more flowers to complete its lifecycle, which we are artificially prolonging for our viewing pleasure.  Ingenious.

In addition, cutting flowers more or less at their prime not only satisfies the need to deadhead, you can also create beautiful bouquets for your home.  If deadheading is not your style, you can let plants go to seed, which is appreciated by many species of birds, and will increase the number of plants you have without having to buy more.  Also ingenious.

This bindweed clearly should
have been pulled long ago. There
are plants in there somewhere...
(Photo: M. Truslove)
Weeding and more weeding.  Some folks love to weed--all...summer...long. I have to admit, this isn’t me.  I do love the look of a newly weeded, tidy garden, but by the time mid-summer rolls around, it brings less joy and feels like more of a chore, but it is important to keep it up.  Weeds are contending for the same water and nutrients as your more desirable garden plants, so give your plants the advantage and keep it up.  Staying on top of the weeds will also ensure that you’ll have fewer to contend with next season.

When late July rolls around and both you and your plants are feeling less than perky, it is important to keep on top of those small tasks.  Following the tips above will keep your garden healthy and looking its best into fall.

Thursday, July 18, 2013

Treating Chlorosis with Iron Injections

Posted by: Susan Rose, Tri River Area Extension

Grand Junction – Silver maples really struggle in our area.  I share a story with the Master Gardeners, that it wasn’t until I began volunteering at the Extension office that I learned that silver maples are actually supposed to be green – every one I had seen was yellow, so I thought it was normal for them!

While the best choice is to plant a more appropriate tree to begin with, there are still things we can advise the concerned homeowner.  Getting the watering right can go a long way.  The first challenge is to convince the client where the roots actually are.  Winter watering in this area is an absolute must for these struggling trees, as is avoiding excess water over the summer.  If you really want to guarantee chlorosis, ignore winter watering and run a drip daily in the summer, at the base of the tree!  Yes, we’ve seen this all too often.

A soil nutrient analysis would be very useful in determining what the plant actually needs.  Nitrogen is almost always needed as it gets leached out during irrigation, but in the case of the chlorotic maples we may want to consider the plant’s ability to take up iron as well.  In our high pH environment, the iron in our soils is not very available.

If a soil test confirms the need for additional iron, there are several options: soil applied, foliar, or injections.  Caution should be used and the overall health of the tree should be taken into consideration.  Which brings me to the story I want to share with you.

The tree above was injected with iron directly into the base of the tree.  The tree was under drought stress at the time of the injection.

Iron “burns” in a very distinctive way; the twigs and leaves turn a grayish black.
Note that the rest of the tree is now nicely green!

I don’t think the tree is a complete goner, but it will be a few years before it compensates sufficiently to look good again – by which time I suspect it will again be chlorotic.

Thursday, July 11, 2013

Lightning and Trees

Posted by David Whiting, Department of Horticulture & LA, Colorado State University
As reported in local media, last week a mature Honeylocust tree at the Annual Trial Gardens here on campus was hit by lightning and destroyed.  The large trunk was blown apart, with the tree in six large pieces.
Lightning hit this old Honeylocust tree at the Annual Trail Gardens on the CSU Campus.  Photo from The Coloradodan at
An estimated 100 million lightning strikes occur per year in North America.  Colorado is one of the regions with extremely high occurrence of lightning.  Lightning is the greatest natural destroyer of property and kills about 80 people per year in the United States.  In addition, thousands of forest trees are struck each year, sometime starting fires. 
In risk management, people typically take cover in tornados and hurricanes reducing the risk potential.  However, people often don’t take cover in thunderstorms, leading to injury and deaths.  Personally, I love to watch a thunderstorm with lighting mover across the high plains, and have to tell myself to exercise some caution.  In a thunderstorm, straight-line wind microburst often exceed 55 mph.  Outflow winds from a thunderstorm can exceed 100 mph. 
Lightning can suddenly pop some 5 miles away from where the storm is focused.  Last summer, while walking my dog out on the high plains, I enjoyed watching a thunderstorm off in the distance.  Suddenly, without any warning, lightning hit in the open field next to me.  I was lucky and it really reminded that you don’t have to be "in the storm" to have lightning!
Lighting follows the path of least resistance.  When lightning strikes a tall unprotected tree, it may travel down the stem for a distance, then may leave the tree “jumping” to a more conductive tree structure, person, or animal.  Sideflashes can cause serious damage to structures, often starting fires or damaging electrical systems or appliances.  People or animals taking refuge beneath trees during a storm can be seriously injured or killed by sideflash.
As lightning exits an unprotected tree through the roots, it dissipates into the soil.  If people or animals are standing in the area, a potentially harmful or even deadly flow of electricity may go through their bodies, up one leg and down the other.
Thousands of unprotected trees are struck by lightning each year.  Most lightning-struck trees will not be seriously damaged; other will linger for years before succumbing to secondary pests.  Some will die within a short time.  Relatively few struck trees will be completely shattered or blown apart by a lightning strike.  In addition, when severe damage occurs parts of the tree can be thrown hundreds of yards, causing damage.
Several years ago, lightning hit my neighbor’s mature birch tree.  No visible damage was observable and normal growth suggested no injury.  A year later, lightning hit the same tree again.  I will always remember the extremely loud thunder boom!  Limb on the birch tree fell to the ground in a donut shape, as if they were cut off and just dropped to the ground.  However, the trunk was completely blown apart.  A few larger trunk pieces were the size of fireplace logs.  Most of the trunk was rendered to finger size to matchstick size.  Tiny fragments of the trunk were over 300 feet away.  Sideflash to the house damaged the home electrical system, and charred the light switched and electrical plugs on the tree side of the house.  Luckily, the house did not catch fire.
Lightning protection systems in trees are intended to safely conduct the lightning to the ground.  Properly installed and maintained, systems are reported be 98% effective at preventing serious tree damage. 
The National Fire Protection Associations’ Standard for the Installation of Lightning Protection Systems recommends installation of lightning protection systems in trees that are within 10 feet of a structure, that are taller than the structure, and have limb over the structure. 
The National Arborist Association recommends protecting trees of historic interest or high value; trees in recreational areas, parks, gold course, and other areas where people might be injured; and trees more prone to strike because of their location on isolated hills, open pastures, or near water.
Details on tree lightning protection systems are outlined in Best Management Practices: Tree Lightning Protection Systems and ANSI A300 Lightning Protection System Standards. Both are available from the International Society of Arboriculture at
Information Source: Arborist News, April 2003.


Wednesday, July 10, 2013

Death by compost by Irene Shonle

Compost.  It improves the tilth of your soil, increases microbial activity, improves water and nutrient holding capacity, and slowly releases nutrients.  What's not to love?

Well, I learned the hard way that some commercial composts are not  particularly good for the garden.  They may not be all the way finished (they often will still smell of ammonia), and they may be high in salts.  It's not a a bad idea to ask for test results or to test it yourself before applying large quantities.

My particular problem was that the compost was hydrophobic.   I ordered a large dump truck full of compost to use as a top dressing/mulch  around established perennials.  Usually, this is an excellent idea -- it provides nutrients, keeps down weeds, improves soil moisture, and will improve the soil as it breaks down.
So, after spreading it around the plants, I watered it in a bit.  The water just beaded up on the surface and ran off.
Water beading off hydrophobic compost.  You can also see that it is not very "finished", since it still has recognizable wood chips in it

I wasn't particularly worried about it, since some things like dry potting soil can be hydrophobic until they get thoroughly wetted, and then they're fine.  I figured I'd just keep watering it, and once thoroughly saturated, the problem would be resolved.  I especially figured it wouldn't be an issue once it snowed, and the wet snow would keep it nice and moist until it froze hard. 

That was my error in judgement -- even though I had tried hard to moisten it before the winter, our very dry fall last year created a hydrophobic layer at the soil/compost interface that kept the moisture from the snow from ever getting down into the ground.   Over the winter, everything died in the bed that had taken pains to "baby" with extra compost.   What a shocker.  What a bummer.   All those established and beautiful plants, gone!  And here I thought I was helping them by giving them a boost, but instead they died of drought.

The moral of this story is that hydrophobic compost needs to be turned into the soil (it doesn't seem to have the hydrophobicity once it has been mixed with soil)  It can't be used as a top-dressing.  If you intend to use commercial bulk compost as a top-dressing, water it before you spread it.  If the water runs off, learn from me and DON'T use it as a mulch.

I don't think this same problem would happen with home compost, since it rarely gets hydrophobic.  Unfinished home compost could potentially burn roots due to the ammonia, so give it a sniff before applying to your soil.

Tuesday, July 2, 2013

The Beauty of the Prairie

Posted by:  Carrie Shimada, Weld County Extension

With the 4th of July right around the corner, I thought pictures from a day-trip I recently took would be apropos.

I have lived in Colorful Colorado all my life and during that time I have traveled West, to the mountains many (many) times, South, all the way to the New Mexico border, and North, up to the Wyoming border (never stopping to visit any of the towns or recreational areas) - but the furthest East (in Colorado) I had ever been was Ft Morgan and DIA.  (Okay, so that’s a bit of a lie, I did go on a few family trips to Missouri when I was under the age of 6, but who can remember that far back!)

Like many Coloradoans, when I think of Colorado hiking trips or vacations, I think of mountains- not of the plains, but after a couple of recent trips, I suggest you consider a day-trip to the Colorado Plains.
Yesterday, we jumped into the car, last minute, and ventured out to the Pawnee Buttes, located within the Pawnee National Grasslands.  This trip, according to US Forest service, is 25 minutes northeast of Greeley, 35 miles east of Ft Collins, which seems like a quick trip, right?  But, beware if you want to venture into the 193,060 acre region or to the Pawnee Buttes area- be prepared for very bumpy gravel roads.  While facilities are limited, recreational opportunities are not.  This area is an internationally known birding area (May-June are the best) and a good place for a grassland hike.  Instead of ponderosa pines or aspen tress, there are yucca plants, cactus, and a quite serenity that is only found on the prairie.  Here is my pictures.

We finally arrived....after a very bumpy ride.

The Map.
Beware of the took two of us to figure out!

The official Pawnee Buttes.

It wouldn't be a hortie blog without plant pictures!

This is one of the only places yucca belongs :)

The interpretive signage.  At one point in time titanotheres
(a rhino-like creature) roamed here.

My dog, Magnolia Jean- if you take you dog,
bring plenty of water and watch out for cactus.
My Selfie :)

Thanks for joining me on my adventure!