Temperature (degrees F):

Average High: 98.3 degrees
Lowest High: 66 degrees (1895)
Record High: 116 degrees (1950)

Average Low: 72.8 degrees
Highest Low: 90 degrees (1982, 1983)
Record Low: 47 degrees (1895, 1965)

Note: Rainfall and temperatures vary widely within the valley depending upon elevation and microclimate.

To Do List . . .
Turf

Fertilize Bermuda-grass lawns with Nitrogen each month beginning late April or early May according to the directions on the package.

Apply Iron each month according to the directions on the package.

Apply one inch of water per week to Bermuda lawns

To remove a Bermuda lawn

• Water and fertilize the grass to ensure that it is actively growing
• Apply a herbicide with glyphosate according to the directions on the package
• The grass will take in the herbicide throughout the entire root system, thus killing the plant rather than just knocking it back
• After a few days water again
• Reapply the herbicide to any of the turf that regrows
• Continue this cycle (may take three or more times) of fostering growth and applying herbicide until the grass is completely killed

Vegetables

Solarize garden soil: Prepare bed for fall planting, irrigate and then cover with clear plastic for six weeks. This will kill or drive out many of the soil pathogens.

Prepare bed for fall planting

Plant Seeds

Snap Beans, Beets, Bok Choy, Broccoli, Brussels Sprouts, Cabbage, Chinese Cabbage, Carrots, Cauliflower, Celery, Chard, Collard Greens, Cucumbers, Endive, Kale, Kohlrabi, Lettuce (Head & Leaf), Leeks, Mustard, Green Onions, Peas, Radishes, Spinach, Turnips

Plant Transplants

Broccoli, Brussels Sprouts, Cabbage, Chinese Cabbage, Cauliflower, Celery, Chard, Lettuce (Head & Leaf)

Resume full fertilizing of established roses as the weather cools

Toward the end of August and into September add an iron supplement if roses show yellowing from iron deficiency

Fruit and Nut Trees

Late summer application of nitrogen fertilizer probably helps fruit sizing. This is more significant for fall ripening (navels & tangerines) than spring ripening (Grapefruit and Valencia orange) varieties.

Apply nitrogen and zinc to pecan trees to produce normal size leaf growth and to enhance kernel development. Pecans also need more water than most other shade trees.

Landscape Plants

Increase water application as the weather warms.

Apply mulch to the ground around heat sensitive plants keep the roots cooler and prevent evaporation.

Apply chelated iron to bottle brush, pyracantha, silk oak, and other plants with iron deficiency symptoms.

Cut off spent blooms to stimulate rebloom

Native and imported heat tolerant plants can be planted right through the summer months. They will need to be watered on a regular basis until fall.

Transplant palms in the heat of the summer for best results

Protect newly transplanted trees from heavy winds and dust storms by staking carefully

Late August or early September fertilization will benefit most plants struggling to have a flush of growth before slowing down for the winter. The growth put on before dormancy will store more energy during the winter that will be available to the plant when it pushes growth in the spring.

Don't List . . .

Do not expose citrus and other sun sensitive plants to sunburn by pruning during the summer

Do not increase opportunities for fungal disease on turf by over watering or watering at night.

DO NOT OVER WATER which will result in root rot. Allow the soil to dry out between watering.

Frequently Asked Questions during September
in the Low Desert

Damage is Noticed on the Fruit

Citrus fruit split
Inappropriate water management leads to sunburn, or tough rind that is then unable to expand as fruit matures. There is nothing to be done for this season, monitor irrigation carefully next summer.

Damage is Noticed on the Leaves

Leaves of vegetables (particularly cabbage, broccoli, cauliflower etc.) being eaten by snails, slugs, cabbage loopers, or birds.

Bermuda grass is turning yellow-brown and dying in patches, there are tiny white flecks in the soil around the roots

There are tiny little white flies everywhere!

Agave collapsed into a smelly, putrid, mess practically overnight

Seedlings have been clipped off right at the soil line

Older leaves turn yellow and fall off. The plant is stunted. It wilts even when water is available The stem is streaked.

Very sudden die back of an olive tree branch. There is brown or green streaking between the bark and the wood.

There is a gray or white powdery substance on plants

The bark is discolored on the South or West side of the trunk

There are brown balls/galls on the stems of oleander

Dry, thin bark cracks and splits to reveal black, powdery spores. Foliage above the wound is sparse and leaves may be small. Eventually branches die back to the canker.

Saguaro cactus has large black patches that are oozing and smell terrible

Whole tree, or significant portion of plant died suddenly, the leaves turned brown but did not fall off.

Older leaves turn yellow and fall off. The plant is stunted. It wilts even when water is available The stem is streaked.

Very sudden die back of an olive tree branch. There is brown or green streaking between the bark and the wood.

Cultural / Environmental Questions

Citrus fruit split
Inappropriate water management leads to sunburn, or tough rind that is then unable to expand as fruit matures. There is nothing to be done for this season, monitor irrigation carefully next summer.

The bark is discolored on the South or West side of the trunk

Insect/Pest Questions

Bermuda grass is turning yellow-brown and dying in patches, there are tiny white flecks in the soil around the roots

There are tiny little white flies everywhere!

Agave collapsed into a smelly, putrid, mess practically overnight

Seedlings have been clipped off right at the soil line

Leaves of vegetables are being eaten by snails, slugs, cabbage loopers, or birds.

Disease Questions

There is a gray or white powdery substance on plants

Seedlings and bedding plants wilt and die suddenly

There are brown balls/galls on the stems of oleander

Saguaro cactus has large black patches that are oozing and smell terrible

Older leaves turn yellow and fall off. The plant is stunted. It wilts even when water is available The stem is streaked.

Very sudden die back of an olive tree branch. There is brown or green streaking between the bark and the wood.

Whole tree, or significant portion of plant died suddenly, the leaves turned brown but did not fall off.

To Gardening & Landscaping in Maricopa County, AZ

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Timely Tips for September in the Low Desert

Last Updated January 3, 2006

© 1997 The University of Arizona, College of Agriculture, Cooperative Extension, in Maricopa County. Comments to: Maricopa-Hort@cals.arizona.edu 4341 E. Broadway Road, Phoenix, AZ 85040, (602) 470-8086 ext 301

http://cals.arizona.edu/maricopa/garden/html/t-tips/sep-txt.htm