Alamosa Landscapes: Suckers, Cosmos, and dill


This might fall under the category of “Be careful what you wish for.” I wanted shade, gently reseeding flowers, and a tasty herb. Besides typical August garden duties such as deadheading and collecting flower seeds, I’ve been spending a lot of time removing tree suckers and pulling up Cosmos and dill. Not my favorite tasks!

Fifteen or so years ago we planted a narrowleaf cottonwood (Populus angustifolia).  While it is now a large tree providing wonderful shade, it also provides a profusion of suckers each year. I didn’t realize that it produces many more suckers than the lanceleaf  cottonwood (Populus x acuminate) that also does well in Alamosa.

It didn’t sucker the first few years, but now I pull up suckers as far away as 40 feet from the tree. Trees with shallow root systems are more prone to suckering than others.  If the sucker is in a garden bed, I try to dig down, find the horizontal root connection and cut through the root. I  pull up as much as possible of the horizontal root.  If I just pop the sucker off the root, more suckers will develop. If it is between flagstones or out in the gravel driveway, I  use Roundup to tackle the problem if the sucker is more than 20 feet from the tree. You might wonder, why not just apply an herbicide all the time?  The problem is it could kill the entire tree.

According to the University of Arizona Cooperative Extension website, “These suckers sprout from adventitious buds.” Adventitious, when used in botany, means anything that grows where it normally would not. In this case, entire new trees can develop from underground roots. The site goes on to report, “When removed, a wound is also left behind creating an entry point for disease organisms to establish themselves.”  I haven’t had any problems with disease.

If suckers are around the base of the tree as happens with Canada chokecherry (Prunus virginiana), I use a different technique. I use a trowel and dig into the soil around the root suckers without disturbing the tree roots.  I then cut them off as deeply as possible.  After doing this, the Gardens Alive website says to, “Bury the remaining root sucker with the soil you removed when you dug around it. The object is to prevent sunlight from reaching the sucker, which can cause it to grow back.”

I mentioned in an earlier column that I lost a lot of plants over our warm, dry, and windy winter. These were mostly in beds with nice loamy soil.  Once I started watering, and especially after we received some much needed rain, an abundance of annual Cosmos daisies popped up along with the usual weeds.  I’ve had Cosmos for years, but they didn’t pose a problem until this year. Sadly, they are crowding out more desirable plants.  The taken-over beds still have some specimens of perennials that have done well for many years and I want them to spread.  They include flowers such as May night sage (Salvia nemorosa), Icelandic poppies (Papaver nudicaule),  party girl miniature hollyhock (Sidalcea ‘Party Girl’), Indian blanket flower (Gaillardia), pink/red yarrow (Achillea ‘Paprika’), and sea holly (Eryngium). And the Cosmos are popping up along gravel garden paths – I’ve never had this happen before.

I’ve already filled three trash cans for recycling and will fill at least one more. When I pull undesirables that are near other plants, I try to pull them carefully and bang the roots against a rock to try and remove as much soil as possible.  I’ve worked for years to improve the soil and don’t want to haul it to recycling.

I complained about this to a friend at the Farmer’s Market over the weekend. She mentioned that she can’t get Cosmos to reseed whether she starts with plants or seeds.  On the other hand, perennial lupines spread readily in her yard while I can’t seem to keep a lupine alive for more than two years and have never had them spread.  I’d rather have lupine that Cosmos! Each garden is mysteriously different.

The profusion of dill (Anethum graveolens) in at least one bed is a surprise this year.  It has inundated a bed where I love to have low flowers, such as iceplant (Delosperma species), native Great Plains verbena (Verbena bipinnatifida), low asters (Aster species), and creeping baby’s breath (Gysophila repens). As those of you who grow dill or buy it in the store know, it can grow up to three-feet high.  It then shades out the shorter plants. Pull, pull, pull!

What is a weed?  I have heard it said that there are sixty definitions.  For me, a weed is a plant out of place.” Donald Culross Peattie

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