Heatwave in the Garden: how to identify and prevent heat stress in plants

 (Reposted from Oregon State University Extension June 2021)

When a heatwave hits, plants may show the impact.

• Most plants grow best in temperature ranges 59-86F.
• When temperatures above 90F are sustained for long periods, plant growth is slowed, and some plants begin to show signs of stress.
• Above 104F, many plants will survive but will show different signs of heat stress dependent on plant type, maturity of the plant, and factors that often come with high temperatures, such as drought or wind.
• Extreme air and soil temperatures slow down chemical activity and growth in plants.

What are signs of heat stress in plants?

My First Attempt at Winter Sowing by Dawn Savage

Photo:  Dawn Savage

I’m not a big social media person, but I do follow a few gardeners on Instagram and You Tube.  I noticed a topic, Winter Sowing, which kept coming up.  It touted the ability to start seeds without needing indoor space, grow lights, or other specialty equipment.  The upfront costs are empty opaque gallon milk jugs, potting soil, seeds, scissors, duct tape, and some outdoor space.  Why not, I thought.   It will keep my hands busy and my mind dreaming of springtime.

Name that Houseplant! by Amy Norwood

Photo:  Amy Norwood

Last fall I bought a houseplant at a big box store.  It was attractive, healthy and priced well.  The tag on the plant said “tropical plant.”  That told me I couldn’t leave the plant outside over the winter because it would freeze and die in Colorado’s climate.  The plant grew nicely in my house over the winter and it didn’t seem important for me to know exactly what plant it was.  As spring approached, however, I wanted to identify it so I’d know whether and where I could put it outside in the summer.  I also wanted to know the watering and fertilizing regimen it needed for the upcoming more active growing season.

Some Plants Do Best with Neglect by Nancy Shepard

Caring and nurturing our plants is an instinctive feeling we have as gardeners. Watering, weeding, trimming, and fertilizing are front and center in our minds throughout the growing season. But that caring can sometimes go wrong, especially as we start to use more water-wise and native plants. 

Digitalis thapsis (Spanish Peaks Foxglove)  planted in hot and dry area
Photo: Nancy Shepard

Digitalis thapsii, or Spanish Peaks Foxglove is planted in two different parts of my yard. One in a south-facing, parched area near a hot brick pathway and the other in part shade within a retaining wall that gets some moisture. The plants were put in at the same time. The hot baked location is showing incredible results, while the other is struggling to survive. While it has the name Foxglove, Spanish Peaks is nothing like its cousins which need shade when the summers get hot. 

Digitalis thapsii Spanish Peaks Foxglove in part shade with moisture
Photo: Nancy Shepard

Rocky Mountain Penstemon (Penstemon x mexicali Pikes Peak Purple)
Photo: High Country Gardens

I also planted Rocky Mountain Penstemon (Penstemon x mexicali Pikes Peak Purple) in several locations around my yard and these suffered because I watered them. They grew leggy, limp and fell over. I stopped watering them and they look great now.

Nepeta x faassenii 'Walker's Low' Catmint
Photo: Nancy Shepard

One of my Nepeta catmints (Walker's Low) developed a big hole in the center and spread out flat because of too much water and the shade of a tree. The one out in the relentless sun didn't have that problem. Described as thriving in harsh conditions, this durable, rabbit and deer resistant perennial plant is an indispensable for use in xeriscapes. 

Linum perenne Blue Flax
Photo: Wikipedia

Same with Linum perenne Blue Flax. I planted both seeds and seedlings. As long as I leave these alone and skip watering them, they have continued to bloom straight and tall all spring.

I’ve had to relearn how and when to water if at all with these xeric specimens. It's been a little tricky because they are planted among perennials that need some water, but I'm getting better at it. As our summers in Colorado continue to get warmer, I'm seeing my garden with a different perspective. And hopefully my water bills will show it!

 

 

How to Recycle Your Plant Pots by Nancy Shepard

 

By now you’ve probably planted all your annuals and added more perennials to your garden. What to do with all those plastic pots you brought home?  In researching this topic, I had hoped to find a conclusive answer, but the recycling industry is much more complex than I thought. I used to think I could throw them in with my regular recycling routine but I found out that many recyclers don’t want these pots.

Since most flower pots are dark green or black and are made from a variety of plastic resins, they say to put them in the trash. The reason it is hard to recycle dark colored plastic is because recycling facilities sort plastics by bouncing a beam of light off them. Since black plastic absorbs light, it can't be sorted and goes straight through the system and off to the landfill or incineration. The same is true for really dark colors in general (dark grays and sometimes navy.)  It's best to either reuse them or see if any nearby nurseries or home improvement stores will take them back for reuse.

I found that Lowe’s has a recycling program for these pots, although I can’t say exactly what they do with them. They usually have a shelf inside the garden center where you can drop yours off.

Lowes pot recycling shelf in garden center

Lowes plant pot recycling

Home Depot advertises that they do plant pot recycling and use this picture on their website:

Home Depot plant container recycling program

If you do not have a Lowe’s or Home Depot nearby, ask your local garden center whether they will take back trays and pots.

Some good news I found: companies are making pots out of recyclable resins now. For example Terracast uses Linear Low Density Polyethylene to create new pots from recycled ones. Let's hope this trend continues!

https://www.terracastproducts.com/planters-from-recycled-materials-all-about-recycled-plant-pots/

Bombus, the Humble Bee by Kimberly Sheahan

Photo by Kimberly Sheahan
Bombus nevadensis #1

The bumble bee’s scientific name is Bombus and prior to the 1920’s they were more often called “humble bees” due to the soft droning noise they emit. Unfortunately, a few articles in the 1920’s referred to them as bumble bees and the new name took. (I personally vote that the internet reclaim the common name humble bee to refer to these fuzzy pollinators.)