Shrub/Tree problems & June Blooms

by Marilyn Loser

2019 June 26

Last time in this column I talked about plants that are performing well this year.  However, it turns out some shrubs and trees aren’t doing so well even with our more than double normal rainfall (5.1 inches to date).  How can this be?  I think Adam Moore, our district Supervisory Colorado State Forester, has a very good response.  He said we had a severe drought last year.  Following that we had a cold winter with lots of moisture, but the trees had gone dormant, the ground was cold, and the trees couldn’t absorb the moisture. They are showing damage now from last year and need regular weekly water.

I’m trying to keep up!  A couple of my Austrian pines (Pinus nigra) have brown branches on the south side.  It could be winter burn or it could be low water as they receive less water on the their south sides.  I have to do something about that! Our Autumn Blaze maple (Acer x freemanii) has sad looking small branches at the top – not sure if it was due to a late freeze or lack of water.

On the other hand, our bur oak (Quercus macrocarpa) and hackberry (Celtis occidentalis) trees look healthier than they have for a couple of years!  No die back, and green, healthy leaves.  I’ve had both of these trees for several years and they leaf out later than our other trees.  I think they missed the freezing temperatures in late May and early June.  Also, hackberry is considered a drought tolerant tree.

Older shrubs are having the hardest time.  I had to cut out a lot of dead branches in a couple of our golden currants and wild yellow roses.  I still have plenty of pricks on my arms from pruning the roses!  Comparing photos from last year to this, I’d say I cut out about ¼ of the growth from one yellow rose.  Dang.

Other older shrubs that needed pruning to cut off dead branches include spirea (Spiraea nipponica 'Snowmound'), juniper (Juniperus), mock orange (Philadelphus lewisii 'Cheyenne'), forsythia (Forsythia), sand cherry (Prunus besseyi), rabbitbrush (also called chamisa - Chrysothamnus nauseosus), and woody fernbush (Chamaebatiaria millefolium). None of the shrubs I planted last year or the year before were damaged.  Since I water newer plants more frequently in order to get them established it could be I underestimated what the older plants needed during last year’s drought.

Many shrubs that do well in our environment have most of their roots in the top 24 inches of soil.  I suggest watering deeply and monitoring the soil moisture to determine how frequently to water. I have a simple moisture tester that does the trick.  You can get them for 10 dollars or less.

I’m still trying to keep up with weeding! With our wonderful precipitation and years of seeds not getting enough water to germinate, they’re having a banner year!  My main challenges are white top (hoary cress – Lepidium draba; perennial pepperweed- Lepidium latifolium), cheat grass (Bromus tectorum), lambsquarters (Chenopodium album), and bindweed (Convolvulus arvensis). Colorado has a very good noxious weed website. The URL is long so I suggest searching on “Colorado noxious weeds” – it’s a .gov website. I find I have to make sure to get all of the roots or they just come back. White top is especially awful.  I don’t remember seeing it until about six or seven years ago.  Now, it is all over town.  It may look pretty in the spring, but it seems each plant has a million seeds and they sprout with just a drip of water.  The roots are tenacious and spread laterally so are hard to get rid of.

On the positive side, we had 75 different plants blooming on Monday.  Take a look at the list on the homepage.

Flowers really do intoxicate me.” Vita Sackville-West