Thursday, May 17, 2018

Tree Planting No-No's!

Posted by:  Amy Lentz, Weld County Extension

It’s planting season all across Colorado, from agricultural crops to flowers to trees. It’s the latter that I want to address today in this blog…planting trees! Our towns and cities are growing (fast!) and with this comes the planting of a LOT of new trees, both in public spaces and on private property. Planting trees in the correct manner is the most beneficial thing you can do for a tree’s health as it will be the foundation of the tree for the rest of its life. If these newly planted trees start off at a disadvantage, it could invite many insect, disease and other tree health issues down the road. And let’s be real, trees are not cheap! They are quite an investment that will eventually pay off down the road once the tree matures…if it’s been properly planted and cared for as it gets established.

Being a tree in Colorado isn’t all that easy with our dry climate, wide swings in temperature and less than ideal soils in most locations (among other hurdles). This makes it ultra-important to help these newly planted trees get off to a good start in life. If planted incorrectly, these trees can be doomed with a death sentence from the day they go in the ground, but you won’t see it right away. In many cases, a poorly planted tree will not show symptoms of poor planting until a few years later.

Here’s my list of 5 Tree Planting No-No’s:


You should plant the tree so the root flare (where the tree’s trunk meets the top of the roots or the top of the root ball) sits just slightly above the existing soil level, 1 to 2 inches. Measure the root ball before you start digging and check the depth periodically as you go down. You can always remove more soil if the hole is too shallow, but soil that has been added back into the planting hole will not act the same as if it were not disturbed. Instead, it will settle and the tree will likely sink causing it to be planted too deep.


The hole should be 3 times the width of the root ball of the tree and have sloping sides. This is especially true for trees grown in containers, as their roots need to adjust from growing in a barky potting mix to growing in heavy soils. Digging the hole wider will loosen the soil so the roots can grow and adjust more easily to the native soil.


This tree was easily pulled from the ground years after it was planted. It had a very poor root system due to the wire basket being left in place at planting. A Big No-No!

I can’t stress this enough. I have seen trees succumb to a slow and horrifying death because wire baskets have been left in place. Not only is the tree you've invested in dead after a few years, you have also lost years of growth and will have to start over. Burlap and rope should also be removed as these will not break down fast enough in our Colorado soils, hindering the root growth of the tree and causing the same demise. So take the time to remove the basket and place the tree gently into the planting hole. This is also a good time to check for circling roots or roots growing across the base of the trunk and direct them away from the base of the tree.


Just say no!

I have seen a lot of this lately! Trees take up water and nutrients from their roots, not their trunks. Therefore, the trunk does not need mulch to help conserve water or protect the tree. Instead, it hurts the tree. Having mulch piled up around the base of a tree can lead to the wood rotting and inviting pests and disease to attack the base of the tree. Don't get me wrong...mulch is a great thing! I love seeing trees with good-sized mulch rings underneath as this creates a favorable environment for the tree’s roots and keeps mowers and string trimmers away from the tree. So use mulch, just use it in a 2-3 inch layer out to the drip line for a new tree, keeping it a few inches away from the base of the trunk.


Too tight.
Just right.

A newly planted tree needs encouragement to grow strong roots. Think of it like an arm in a cast…without the ability or need to move the muscles, they become weak. If we baby a newly planted tree too much by tightening the staking straps to the point of no movement, the tree will not form as strong of a root system because it doesn’t have to in order to remain upright. Staking straps should have a little wiggle room so the tree can still sway in the wind. Furthermore, if they are too tight, they could girdle the tree’s trunk as it grows in size. Straps should only be left on for the first year a tree is in the ground.

There are many other helpful recommendations when it comes to planting trees. For the complete story, check out the following resources from CSU:

Tree Planting Steps - Colorado Master Gardener Garden Note #636

The Science of Planting Trees - Colorado Master Gardener Garden Note #633

Tuesday, May 15, 2018

Iris Season

Iris Season
By CSU Horticulture Program Associate, Linda Langelo
This is my favorite flower, among other favorites.  Of all the unique, unusual flowers iris stand above the rest with their bold, showy petals.  Of course, there is no bias here.  Irises can create a mass of color that is striking, but don't blink.  That color disappears quickly.  However, they are memorable. 
The best part is that they come in all colors.  No matter what the color palette of your landscape there is always room for an iris to match or compliment.  From white to every color of the rainbow and then dark, rich colors such as purple and black.
Iris are easy maintenance.  Their rhizomes love to bake in the heat of the summer.  After the first frost in the fall, their leaves need to be cut back.  In late spring or early summer after they bloom, if they have lost their vitality or are not as prolific, it is time to divide the iris.  Dig up the rhizomes using a digging fork, anytime from July through September.  The heat and dry soil in summer is perfect for discouraging soft rot on the rhizomes.  Separate the old clumps of rhizomes by using a sharp knife.  Dip the knife in 10 percent bleach solution between dividing clumps.  It is best to save the strong outside pieces of a clump.  Cut the rhizomes into pieces with each having a single fan of leaves.
Photo Credit:  Gardenia-Creating Gardens- Iris 'Beverly Sills'

Also cut the leaves down to a third of the original length.  Then plant the divisions with the rhizomes barely covered.  Plant them so that the fans are facing in one direction.  For those of you who are visual learners here is a short series of instructions, illustrated through photos.

Here is a picture step-by-step instructions for dividing iris from University of Maryland Extension:

Photo Credit: University Of Maryland Extension

Step 1: Dig irises by using a spading fork.

Photo Credit: University Of Maryland Extension

Step 2: Remove the soil and check for root rot or borers.

Photo Credit: University Of Maryland Extension

Step 3: Discard old or rotten rhizomes.  Cut the rhizomes to a few inches(as you will see in the next slide.)

Photo Credit: University Of Maryland Extension

Step 4:  Let the newly cut rhizomes stay in the sun for a day or two.  During this a suberization process occurs meaning - to make impermeable by the formation of suberin in the cell walls, changing them into cork.  The cells suberize.

Below is an iris now blooming at my house:

Photo Credit: Linda Langelo

I moved into a new home last year and a friend had asked if I wanted some iris.  I had flower beds but they were completely empty.  He said that they were yellow and that is all that he knew about them.  A mystery iris.  These iris flower early and are shorter than most.  They are perfect for the backdrop of the foundation which is painted green.  I think I have them properly identified as Scholar.  Scholar gets to be 13 inches and is a standard dwarf bearded iris.  It was developed in 2000 and does not rebloom later in the season.  It flowers early meaning early May to mid-May and will continue for another week depending on the weather.  I identified my mystery iris.  Do you have a mystery iris in your garden?

Thursday, May 10, 2018

What’s That Bug (Egg): Mantids and Katydids

Posted by Jessica Wong, Master Gardener Coordinator, Broomfield County Extension 

Winter can be a dull time for an entomologist. Like many plants, some insects go dormant for the winter. But now it is spring and the insects have resumed activity and so have the entomologists. 

Something that looked and felt a bit like a packing peanut glued to the branch of magnolia was brought in to the office a few weeks ago. This “packing peanut” is actually an egg case of a European mantid, Mantis religiosa. European mantids are non-native to Colorado, but they are well established here. In fall they lay multiple eggs (sometimes hundreds!) covered with a dried insulating foam on pretty much any solid surface. The eggs survive through the winter and start hatching in late spring. With this heat wave, some baby mantids might already be out. They look like the adults, but smaller. 

European mantid egg case on magnola. Photo by Jessica Wong
Gardeners like mantids because they are predators that feed on various insects, including some pests. However, mantids can be picky eaters and may not provide effective pest control. They mostly feed on gnats, flies and bees. A young mantid may cannibalize others as they emerge from the same egg case, and an adult female typically only eats the male during mating if she is starved.

Female European mantid laying eggs. Photo from by Lynette Elliot
More recently, a butterfly bush twig with two meticulous rows of eggs came in to the office. These are the eggs of a broad-winged katydid, Microcentrum rhombifolium. Their eggs can be found in double rows on twigs or in single rows on leaf margins. Similar to mantids, these katydids lay eggs in the fall that hatch in the spring. Katydids are herbivorous and will feed on the leaves of shade trees and other ornamental plants. However, they do not occur in high concentrations and typically do not cause harm to plants.

Double row of broad-winged katydid eggs on butterfly bush. Photo by Jessica Wong

Broad-winged katydids are seldom seen, but are often heard at night in the summers in Colorado. The males make loud “lisp” and “tick” sounds, and females respond with less audible clicking. Katydids produce sounds by rubbing the bases of their wings together - a process known as stridulation. On the base of one forewing is a set of tiny pegs called a file, and on the other forewing is a ridge called a scraper. The wings also have a smooth membrane that amplifies the sounds made from rubbing the file and scraper together.

Spring has just begun, but these insects have me dreaming of summer already.

Broad-winged katydid male. Photo from Colorado State University "Colorado Insect of Interest"