Winter Weed Control

Soaking rains bring much-needed water to our desert environment, including plants. Rainwater is especially beneficial to plant material as rainwater is less alkaline than our irrigation water. While rain is a positive thing for our plants and irrigation water bills, it also helps weeds grow. For effective weed control in your yard, manual removal is the easiest way to get rid of a small number of weeds. To control weeds over a large area, herbicides are the most efficient tools available. There are two categories of herbicides for weed control: Pre-emergent and Post-emergent.

Post-emergent for winter weeds: Post-emergent herbicides kill weeds that have germinated and are visible in the landscape. To kill weeds in winter months, you need to use a herbicide containing Diquat. Spectracide products, which contain Diquat, are available for personal use at most home improvement stores or nurseries.

Pre-emergent herbicides: Pre-emergent herbicides are designed to prevent seeds from germinating in the soil. They are most effective when applied during the rainy season. In Arizona, that means either before the summer monsoon in June & July or from October through January to take advantage of the winter rains. A timely application of pre-emergent can greatly reduce the number of weeds that germinate since it inhibits the weeds’ roots and does not allow them to grow.


The Benefits of Not Overseeding

The Growing Season

header_turfDoes your warm-season, hybrid Bermuda grass look sparse or weak?  The culprit may be continuous overseeding. Often times, this is due to the competition for nutrients between the Bermuda grass and the perennial Ryegrass used in fall overseeding. Overseeding leaves the Bermuda needing recovery time to build strength and vitality before the next growing season.

Overseeding in the fall does not allow Bermuda grass to complete its normal growing cycle before winter dormancy approaches. Much like a bear preparing for hibernation, Bermuda spends the weeks and months prior to the cold season storing the reserves it needs to keep its roots and stems alive through the winter. Overseeding interrupts this process and often, die-back results in the root system. The effects of interrupting this process are seen in the spring when weather conditions are right for Bermuda to begin growing again. The thick, tall Ryegrass will keep the Bermuda shaded and cool, which prolongs the dormancy period.  By keeping the Bermuda dormant longer, the percentage of Bermuda that runs out of food before it can begin to photosynthesize increases.

When the Bermuda does come out of dormancy, it must contend with the Ryegrass for nutrients while the Ryegrass is at its strongest. Ryegrass is a fierce competitor for all the resources required for Bermuda to grow: sunlight, water, nutrients and even oxygen. During early spring, the Bermuda is at a disadvantage during the time it should be strengthening to withstand the extreme heat and dryness of a typical Arizona summer. By mid-summer, the Ryegrass dies out and physically impedes the Bermuda’s ability to spread. The dead Ryegrass must be removed through dethatching, which may further injure and set back the Bermuda. In most cases, the Bermuda does not get the time needed to recover because overseeding starts again in just a few weeks.

Bermuda Comparison

We recommend suspending the overseeding process for at least one season to help restore the root system and nutrients of the Bermuda grass.

During the Dormant Months

Not overseeding turf areas with winter Ryegrass changes the focus of your seasonal practices. The steps below will help you prepare for the next season of Bermuda grass during the winter:

•  Mow twice monthly to maintain a clean appearance and
even look

•  Control weeds

•  Top dress to fill in holes and areas of compaction

What to Expect

turfBermuda grass can stay green until the first frost, usually the middle of December. Around the middle to end of March, when nighttime temperatures begin to approach 60 degrees, Bermuda starts to grow again and returns to a regular mow and care cycle.  It should also be noted that by not overseeding there are significant savings that can be helpful to any household. Click the link for an article written by a Water Conservation Specialist, highlighting some of the additional benefits.

Estimated Cost Savings

Planting Winter Annuals

Get Ready for Winter Color

Winter AnnualsOne of the advantages of our climate is that we can have bright, colorful flowers in our gardens all winter long. Late September or early October is a good time to start getting ready to plant winter flowers as temperatures will soon begin to sink following the hot summer weather. The time to plant is when daily temperatures are consistently lower than 100 degrees. Plan to begin preparing beds up to two weeks ahead of planting time.

Soil preparation is essential to growing winter annuals successfully. Make sure your planting bed is well drained. Then, add organic amendments such as peat moss or compost. A variety of mulches for this purpose are generally available at a local home improvement store. Spread about a 4″ layer of the mulch over the bed and mix it into a depth of 12 inches. Fertilizer and sulfur can be worked into the soil at the same time. Use Sulfur-coated urea or ammonium phosphate (16-2-0) at 1-3 pounds per 100 square feet of bed area and 3 pounds of sulfur per 100 square feet.

When your soil is ready, you can contemplate which varieties of flowers you want to plant. Calendulas, Geraniums, Pansies and Petunias are some good choices that grow well in winter in the low desert, but there are many others as well. Sweet Alyssum and Lobelia are best for borders around the edge of your flower beds. At the nursery, select the healthiest plants you can find. Younger plants are generally a better choice than tall, leggy plants that have already spent a long time in the container. Naturally, you should choose flowers that are suited to the sunlight available at the location of your flower bed (full sun, partial sun, constant shade).

Root BallPrior to planting, water the bed well. Plant when the soil is still moist, but not saturated with water. Do not plant too deep! The stem of the flowers should be at the same depth in the bed as it was in the container. You may want to carefully open the sides of the root ball with your fingers to promote quicker root growth into the soil of the bed. Water the bed well immediately after planting and continue to water daily. In some sunny spots, you may want to water at least twice a day as long as temperatures remain high. As the winter progresses, you should reduce water accordingly. Lastly, apply a pre-emergent to the bed for weed control. We suggest Preen, a brand that can be found at most gardening stores.

To maintain a good looking flower bed throughout the winter, it is best to fertilize monthly with ammonium phosphate. You will also need to “deadhead” the flowers as their blossoms fade. To do this, pinch the faded blossom off the stem right at the base of the flower. This will keep the bed looking fresh and also promotes the growth of new blossoms.

Winter Annuals

One of the advantages of living in the Southwest region is bright, colorful flowers year-round. Annual flowerbeds often serve as a main feature at community and recreation center entrances and give the community a brightening up with each seasonal change. Selecting the right annual flowers for the weather is critical to achieving a seasonal burst of color. Add some color to your community with these suggestions:



Geraniums can be planted in a bed all by themselves, or mixed in with other annuals. Size varies with species, although most are low growing, from 3″ to about 2´ tall. Geraniums spread by rhizomes to 2-4 feet, but can be kept in check by periodic dividing. It is important to water geraniums thoroughly and let the soil dry between waterings.



The petunia is a flowering plant that originated in South America. It is a relatively small plant that comes in a variety of colors such as: white, yellow, pink, red, blue, or purple. Petunias are available in four main sizes: grandiflora (the largest type of petunia); spreading (covers about three to four feet of area); multiflora (multi-colored petals); and milliflora (smallest leaves). Petunias thrive in areas with 6-8 hours of sun per day and moist soil.



Snapdragons produce relatively large flowers on their stalks and heads given the size of the plant. This annual comes in a variety of colors and two sizes, which makes it a popular choice for winter color in the desert. Dwarf varieties grow to about 10 inches while the taller types grow to a height of 18-24 inches. Snapdragons do need to be “dead headed” throughout the season to remove the flowers that are past their prime.



As a member of the violet family, pansies are known for their wide variety of bright colors. They make good additions to annual beds in full to partial sun locations during our desert fall and early winter. As with most annual flowers, keep the soil moist and well drained to encourage growth and healthy blooms. These plants prefer not to be crowded by neighboring plants and can grown to 9 inches tall.



The unique shape of this flower makes it an interesting additions to fall/winter flowerbeds. They come in a variety of colors in red and purple family. The flower stalks rise above the round leaves and can grow up to 14 inches tall. Ensure the bed is well drained and plant in partial sun locations.

To learn more about common area planting, request a proposal for plant installation or common areas maintenance, or learn more about DLC Resources, email Rebecca Herro.

For more planting recommendations and information on desert landscape, check out Landscape Plants for the Arizona Desert by the Arizona Municipal Water Users Association (AZMUA).