It’s been an interesting summer with all the insects and disease issues. But those first homegrown ripe tomatoes are a welcome treat.
Vegetables
Plant seeds of quick maturing cool-season veggies (yes, the official third vegetable planting season has begun). Lettuce, spinach, arugula, kale and other leafy greens, radish, kohlrabi and short-rooted carrots can be direct seeded. Look for varieties that mature in less than 50 days. Tuck in seeds anywhere there is a bit of room or use containers.
Tomato diseases are most noticeable on mature plants around this time. Tomato spotted wilt virus (TSWV) is out there in high numbers. Symptoms start out as small dark brown to purple flecks or spots on leaves. It’s easily confused with early blight (which is also happening). As the disease spreads, the leaves become stiff, not limp, and the fruits develop yellow rings or spots and may be distorted. This is not a soil-borne fungus but one carried by western flower thrips. There is no cure, so the plant needs to be pulled immediately and not composted. Get a firm diagnosis from your Colorado State University Extension office or garden center. More
Large leafed vegetables, including squash and pumpkins, may wilt during the heat of the day. This is normal transpiration — water moving through the plant. They should bounce back later in the day. Be sure to water plants deeply and infrequently. Use chemical-free dried grass clippings or weed-free straw for mulch, which helps keep soils cooler.
Summer Container Care
Container-grown plants are easily stressed during hot weather and require some extra attention and care to remain healthy and blooming well.
Late summer means bigger plant roots need more water. Clay pots dry out quickly and may need more water during the day than wood, metal, stone, plastic or polymer materials. Feel the soil down two inches or so, and if soil sticks to your finger, then no water is needed.
Empty water from the container tray after each watering to keep any salts from the fertilizer from being absorbed by the plant. Standing water may also be a breeding ground for mosquitoes.
Regularly fertilize container vegetables through the growing season. Time-released granular fertilizers only last a few weeks, so apply again or use a liquid fertilizer. Always read package instructions for application rates; use half-strength once a week to keep the blooms coming.
Tidy up your flower containers by pruning for shape or getting rid of spent flowers and leggy growth (long dead gaps between leaves). Many annuals are on sale at garden centers, so swap out non-performers for some new plants to finish out the summer season.
Now is a great time to start lettuces again. Try something new like mache, mina, mustard greens or the colorful gourmet lettuce blends. They easily grow in pots as small as 18 inches across and 12 inches deep. Keep moist until seeds emerge. More 09378.html
Other cool season plants that do well in containers include radishes, dwarf carrots, spinach, arugula, kale and Swiss chard.
If disease or insects were a problem in the containers, be sure to disinfect (1 part bleach to 10 parts water; rinse thoroughly) and use fresh planters mix.
Insect/Disease Watch
Daddy Long-legs (referred as “harvestmen” in the UK because they were seen most often during harvest season) They are not true spiders, but arachnids. Contrary to myth, they are not poisonous; they simply feed on plant juices and small bodied insects. They can live after losing a leg or two from their four pairs of legs.
Powdery mildew is showing up on such plants as Monardo (bee balm), veronica, lilac, roses, squash and pumpkins. High humidity and susceptible plants accelerate the fungal spores to grow on plant leaves. Powdery mildew is host-specific, so the fungus causing powdery mildew on grapes is a different fungus than the one causing it on lilacs. Left untreated, leaves turn white, yellow, then black before dying and falling off. Avoid overhead watering and remove severely infested leaves (don’t compost). Garden cleanup of infected leaves is a must later this fall. Look for PM resistant cultivars when shopping, and next year try to give host plants plenty of room and air movement to grow. Gentler organic products containing Potassium bicarbonate, Bacillus subtilis or Neem oil are effective for powdery mildew prevention and some control. Other chemical fungicides are available. Home mixed sprays using milk can be effective. More at
To our dismay, it’s been a good summer for black spot on roses. Leaves form circular brown to black spots surrounded by yellow tissue. Canes can develop purplish, irregular blotches. Pick up and destroy infected leaves and prune canes with any lesions so the fungus doesn’t overwinter. Avoid dense planting and look for black spot-resistant varieties. Avoid overhead watering or water early in the day so leaves can dry. Many fungicides are available for spray controls including ones listed for powdery mildew.
Indoor fruit flies or vinegar flies enjoy your summer fruits. They complete their life cycle in 8 to 10 days, so for best control, remove their hangout and breeding spots. Regularly clean sinks and drains, and empty indoor compost pails. Move fruit to the refrigerator until they are under control. Try a homemade trap using a rolled piece of paper as a cone inserted into a jar of apple cider vinegar. More – /
In the Landscape
Maintain proper cultural care to manage fungal diseases and keep lawns healthy. Mowing too short will lead to brown out stress and allow weeds easily to sprout or spread. Set the blade (don’t forget to sharpen) at 2.5 to 3 inches and mow when grass is dry. Leave the grass clippings on the lawn to keep the soil cooler and return valuable nitrogen to the soil; this will not lead to thatch buildup in lawns.
By mid-August, finish fertilization of warm season grasses like buffalo grass. Yellowing of grass could be iron chlorosis, common in buffalo grass. Supplemental iron may be helpful. More
In water gardens, August is the last month to fertilize water lilies if needed. Plants reduce flowering as days get shorter.
There are plenty of sun-filled days left of summer to gather outdoors with friends and family. Snip some flowers and plant foliage for a fresh bouquet and then set the table. Enjoy!
