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Cold shower can help fight spider mites




Brandy hybrid tea roses seem to enjoy the heat. (Photo: Debbie Arrington)


August rose care tips for Sacramento-area gardeners



Consider giving your rose bushes a shower.

More specifically, a cooling spray of water to wash away all that ash and dust on their leaves, preferably early in the morning so leaves will dry quickly. It not only refreshes the foliage, it can help fight spider mites.

Tiny as the period at the end of this sentence, spider mites are one of the few summer rose pests that can take August heat. They stipple (and eventually kill) leaves, sucking the life right out of them. Some species (but not all) leave telltale fine webbing on the underside of foliage. You need a magnifying lupe to actually see the mites.

According to University of California’s Integrated Pest Management research, spider mites love dry and dusty conditions. That’s why we often see outbreaks in the dead of summer. But these little pests can’t stand a good blast of cold water. A watering wand is ideal for this. It allows you to spray up and under the leaves, washing away mites and their webbing.

When mite populations explode, they also inhabit the top of leaves, so wash both sides. In addition, that summer cleaning can help the foliage better do its job, converting sunlight into food for the bush.

Spider mites really flare up when temperatures stay consistently above 80 degrees. Most insecticides and other chemical cures have little if any effect in controlling spider mites. Neem oil or insecticidal soap can put a dent in their numbers earlier in summer. But spraying anything besides water on bushes during this hot weather can cause more harm than good, burning foliage.

Spider mites have several natural enemies than can help keep them under control. Often, a mite infestation follows insecticide application that reduced the number of predators. So, stick to water.

Here are more tips on rose care in August:

Watch out for thrips. The other major Sacramento rose pest of summer, Western flower thrips are minute insects that love to eat rose buds. They tunnel into petals, creating brown trails of destruction. You’ll see the damage before you see the bugs. Control by chemical means is almost impossible because the thrips do their dirty work inside the rose bud.

Thrips tend to attack light-colored, white or fragrant roses. They do the most damage in gardens where roses are tightly packed together. To keep thrips’ numbers in check, dead head spent flowers and dispose of them. The good news? Western flower thrips are a natural predator of spider mites.

Dead head for more blooms. Remove spent flowers in August or bushes will start producing rose hips (their fruit) instead of fall bouquets. With sharp scissors or pruners, snip down to the first outward pointing five-leaf leaflet. The bush will produce another flush of flowers in six to eight weeks.

Water deeply. Mature rose bushes need about five gallons a week in August, more if planted in containers. Bushes in the ground can be deep-watered once a week. In pots, they may need daily watering during triple-digit temperatures.

Mulch is your rose’s friend. Organic mulch (shredded leaves, bark, etc.) maintains moisture, discourages weeds and keeps rose roots comfortable. Maintain mulch at about 3 inches deep, but don’t let it mound around the bush’s crown.

Thin competition. If you grow companion plants around your roses, make sure they’re not strangling the bushes. Those companions are also competing for water.

Feed for fall flowers. To encourage October blooms, fertilize in August. Pull back the mulch and sprinkle bone meal and worm castings around bushes, gently work those amendments into the soil, rake mulch back into place and deep water. Or feed with a half-strength liquid fertilizer after you’ve already deep watered the plants. (Roots need water in the soil to access those nutrients.)

Enjoy your roses. They’ll bloom in this heat when other shrubs shrug and give up. Pick a bouquet to bring inside.

For more on rose pests:
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7466.html and http://www.sactorose.org/rosebug/index.htm

Debbie Arrington is a consulting rosarian and longtime rose grower.

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Flowers in My Back Yard Series

Sept. 15: Plant seeds soon for fragrant spring blooms (sweet peas) 

Sept. 8: A must for fall gardens, asters are little powerhouses

Sept. 1: Yarrow an easy-care, sturdy flowering plant

Aug. 25: Crape myrtles, Sacramento's unofficial tree of summer

Aug. 18: Pollinators adore scabiosa, aka pincushion flower

Aug. 11: Hardy hibiscus adds big tropical impact

Aug. 4: Dianthus a deceptively hardy flower

July 28: Naked Ladies put on summer show

July 21: Thank Luther Burbank for these long-lasting beauties (Shasta daisies)

July 14: How to keep hydrangeas happy

July 7: Grow these bright cosmos for bees and butterflies

June 30: Agapanthus adds blue fireworks to the garden

June 23: Easy-care gazanias fill those hot corners

June 16: Daylilies are perfect for water-wise gardens (and a lot more)

June 9: Grow coneflowers for pollinators -- and yourself

June 2: Sunflowers capture Sacramento's summer attitude

May 29: Are your roses going 'blind'?

May 26: Zinnias are the summer flowers every garden needs

May 19: Plant dahlias now for late-summer flower power

May 12: Know your coreopsis from your bidens

May 5: Mums the word on Mother's Day weekend

April 28: Majestic Matilija poppy is worth a look

April 21: Celebrate roses, America's favorite flower

April 14: Small flowers with outsized impact

April 7: Calendulas do double duty

April 3: Make Easter lilies last for years to come

March 31: In praise of a pollinator magnet (small-leaf salvias)

March 24: Azaleas brighten shady spots

March 17: The perfect flower for beginners? Try zonal geraniums

March 10: Keep camellias happy for years to come

March 3: Fruit tree blossoms are a fleeting joy

Feb. 27: Are your roses looking rusty?

Feb. 24: Treasure spring daffodils now and for years to come

Feb. 17: How and why to grow wildflowers

Feb. 10: Let's talk Valentine's Day roses

Feb. 3: Why grow flowers?

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Taste Summer! E-cookbook

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Find our summer recipes here!

Garden checklist for week of Sept. 13

Now is the time to plant for fall. The warm soil will get these veggies off to a fast start.

* Keep harvesting tomatoes, peppers, squash, melons and eggplant.

* Compost annuals and vegetable crops that have finished producing.

* Cultivate and add compost to the soil to replenish its nutrients for fall and winter vegetables and flowers.

* Fertilize deciduous fruit trees. Make sure to deep water before and after feeding.

* Plant onions, lettuce, peas, radishes, turnips, beets, carrots, bok choy, spinach and potatoes directly into the vegetable beds.

* Transplant cabbage, broccoli, kale, Brussels sprouts and cauliflower as well as lettuce seedlings.

* Sow seeds of California poppies, clarkia and African daisies.

* Transplant cool-weather annuals such as pansies, violas, fairy primroses, calendulas, stocks and snapdragons.

* Divide and replant bulbs, rhizomes and perennials.

* Dig up and divide daylilies as they complete their bloom cycle.

* Divide and transplant peonies that have become overcrowded. Replant with “eyes” about an inch below the soil surface.

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Taste Spring! E-cookbook

Strawberries

Find our spring recipes here!

Taste Fall! E-cookbook

Muffins and pumpkin

Find our fall recipes here!

Taste Winter! E-cookbook

Lemon coconut pancakes

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Food in My Back Yard (FIMBY) Series

Lessons learned during a year of edible gardening

WINTER

Is edible gardening possible indoors?

Hints for choosing tomato seeds

Starting in seed starting

Why winter is the perfect time to plant fruit trees

When to plant? Consider staggering your transplants

How to squeeze more food into less space

Potatoes from the garden

Plant a fruit tree now -- for later

Win the weed war by tackling them in winter

Tips for planting bare-root trees, shrubs and vegetables

Time to give vegetable seedlings some more space

Ways to win the fight against weeds

FALL

Add asparagus to your edible garden

Soggy soil and what to do about it

Plant artichokes now; enjoy for years to come

It's late November, and your peach tree needs spraying

What to do with all those fallen leaves?

Prepare now for colder weather in the edible garden

Plant a pea patch for you and your garden

As citrus season begins, advice for backyard growers

Change is in the autumn air 

We don't talk (enough) about beets

Fava beans do double duty

Seeds or transplants for cool-season veggies?

How to prolong the fall tomato harvest 

SUMMER

Time to shut it down? 

How to get the most out of your pumpkin patch

Summer-to-fall transition time for evaluation, planning

To pick or not to pick those tomatoes?

: Put worms to work for you

Grow food while saving water

Enhance your food with edible flowers

Why won't my tomatoes turn red?

A squash plant has mosaic virus, and it's not pretty

Does this plant need water?

 Tear out that sad plant or baby it? Midsummer decisions

How to grow summer salad greens

 Weird stuff that's perfectly normal

SPRING

Help pollinators help your garden

Battling early-season tomato pests

Make your own compost

Where are the bees when you need them?

How to help tomatoes thrive on hot days

Your plants can tell you more than any calendar can

Maintain soil moisture with mulch for garden success

What's (already) wrong with my tomato plants?

Should you stock up on fertilizer? (Yes!)

Grow culinary herbs in containers

When to plant summer vegetables

Don't be fooled by these garden myths

Fertilizer tips: How to 'feed' your vegetables for healthy growth