Here is Why Common Weeds Love Your Backyard in Tucson
Once in a while, our weed control specialists are called to the rescue by a homeowner whose backyard has been taken over by common weeds. But not just taken over with small sprouts peeking through the gravel. No. Taken over big time. True, this situation does not happen every day. But during the monsoons, absentee owners can easily overlook the fact that weeds will grow, whether or not they are around. Then they come back to Tucson and surprise! … Their backyard has taken a new color.
Over the course of our history in weed control, we have identified 5 main reasons why common weeds can invade a backyard or a front yard, and make it look like we are not in Arizona anymore. Here they are.
1. Monsoon Rainfall & Seasonal Growth Spurts
During our monsoons (the season extends between July and September), we receive sudden, intense precipitations almost every day. This rain, when it does not sheath over the hard dirt but is allowed to accumulate and penetrate it, triggering rapid weed germination and growth.
Weeds are carried by the wind, but they are also largely lying dormant in the dirt, patiently waiting for moisture to sprout. Despite the hard sun of Tucson, the seeds are heat-resistant enough that they wait for a full year before sprouting again. Miracles of nature!
In Tucson and its region, the most common weeds are Russian thistle (tumbleweed), spurge, pigweed, and purslane.
2. Poorly Maintained and Over-Irrigated Landscapes
Drip irrigation is the favorite irrigation method of Tucsonans. For a very good reason: it is the least wasteful of our precious water resources. However, drip irrigation systems are not all born equal, and they are always not installed correctly. Moreover, with the large variations in temperatures between winter and summer, hoses crack and become porous. There is the rub: unmanaged drip irrigation create pockets of moisture (over-irrigation), allowing weeds to grow wild.
If you see a pocket of green in your xeriscaped garden, suspect a break in your line and a leak right around that spot.
However, weeds also grow aggressively in bare dirt, common to xeriscaped yards in Tucson, especially when the dirt is covered with the red gravel we often see in Tucson. The gravel acts as a sun protector for the seeds in the underlying dirt. With a bit of humidity, they will start growing wild and peaking through the gravel.
The most offenders are Bermudagrass, London rocket, and desert broom.
3. Wind-Dispersed Seeds from Surrounding Areas
It is a fact that strong desert winds carry lightweight weed seeds from nearby lots, roadsides, or neighbors’ yards. If your neighbors don’t maintain their yard the way you take of yours, you will wind up with their weeds. Lovely.
Southern Arizona is also the home of the tumbleweed, made famous by countless western movies. Tumbleweed can roll across miles of desert, breaks off, and spread thousands of seeds. Other types of weeds (like Russian thistle, Sahara mustard, and buffelgrass) behave in the same manner. So our yards are always cross-contaminated by remote patches of desert.
4. Failure to Use Pre-Emergent Herbicides
Often out of ignorance, many homeowners don’t apply pre-emergent herbicides in due season (fall and late winter) in their yards. This allows weed seeds to germinate unchecked. Well, without preventative treatments, weeds return season after season. So if you don’t take care of your spraying at the right time, your yard is sure to become a sanctuary for weeds in season.
The most common weeds you will see are mustards, filaree, and foxtail barley.
5. Hard, Compacted, or Disturbed Soil
It may come as a surprise to you, but compacted desert soil is a great refuse for seeds in need of a home. Desert dirt never has a uniform surface: its surface has many cracks which, when dry, allow weed seeds to stay somewhat protected from the sun, and to germinate after a monsoon.
A common sight in Tucson and around the city is the development sites. There, the earth is disturbed by digging, grading, and construction work. Doing so exposes buried seeds to sunlight, which triggers growth. Around these sites, you will often see Goathead (puncturevine), pigweed, and cheeseweed.
There you have it: our top 5 reasons why your backyard will start looking really greeen during the monsoons, and this despite your best efforts to spray your gravels and around your plants. Weed control is a constant battle. You an’t win this war. But you can keep a tidy yard by call on the services of a professional weed control company like Rigo Pest. Call us before the season: we’ll give you a free, thoughtful estimate fully customized to the specifics of your property.
Common Weed Control FAQ
Why do weeds grow rapidly in Tucson during the monsoon season?
Monsoon rains between July and September provide sudden, intense precipitation that penetrates the soil, triggering rapid germination of dormant weed seeds.
How does over-irrigation contribute to weed proliferation?
Leaky or poorly maintained drip irrigation systems create pockets of moisture, fostering weed growth. Regular inspection and maintenance can prevent this issue.
Can wind carry weed seeds into my yard?
Yes, strong desert winds can transport lightweight weed seeds from nearby areas, introducing new weeds into your landscape.
What are the benefits of using pre-emergent herbicides?
Applying pre-emergent herbicides in the fall and late winter prevents weed seeds from germinating, reducing weed infestations during growing seasons.
Why is compacted soil a problem for weed control?
Compacted soil hinders the growth of desirable plants, allowing hardy weeds to dominate. Aerating the soil improves water infiltration and promotes healthy plant growth.
How can I prevent weeds in gravel-covered areas?
Weeds can grow through gravel if seeds settle beneath it. Applying pre-emergent herbicides and maintaining a proper gravel depth can help suppress weed emergence.
Does xeriscaping reduce weed growth?
While xeriscaping conserves water, bare dirt areas can still harbor weed seeds. Using ground covers or mulch can minimize weed growth in xeriscaped yards.
How often should I inspect my irrigation system to prevent weed-friendly conditions?
Regularly inspect your irrigation system, especially before and during the monsoon season, to detect and repair leaks that could create moist environments conducive to weed growth.
What is Russian thistle and why is it a problem in Tucson?
Russian thistle, also known as tumbleweed, is a fast-growing annual that thrives after monsoon rains. Once mature, it breaks off and rolls with the wind, scattering thousands of seeds. It’s a fire hazard and invades open, disturbed soil.
What does spurge look like and how does it spread?
Spurge is a low-growing, mat-forming weed with small, oval leaves and a milky sap. It spreads aggressively through seeds and thrives in hot, compacted soil—especially in driveways, gravel yards, and sidewalk cracks.
How can I identify pigweed in my yard?
Pigweed typically grows upright with reddish stems and broad, fuzzy leaves. It’s drought-tolerant, fast-growing, and produces large amounts of seed, making it difficult to control once established.
What makes purslane so invasive in desert yards?
Purslane is a succulent groundcover with thick, reddish stems and fleshy leaves. It grows close to the ground, tolerates high heat, and can regrow from stem fragments—even after pulling or cutting.
Why is London rocket considered a winter weed in Southern Arizona?
London rocket is a winter annual with yellow flowers and a long taproot. It thrives after winter rains and competes with native desert plants. Left unchecked, it produces dense patches and reseeds easily.
