When you see yellow leaves on a plant, you know there’s a problem.
Unfortunately, this is the upset stomach of gardening.
Yellow leaves represent any number of conditions, including any of the following: Too much water; not enough water; too much fertilizer; not enough fertilizer; exposure to cold temperatures; exposure to hot temperatures; disease; physical damage to the leaves; damage to the roots; and old age of individual leaves.
If you see yellow leaves, look at the plant’s environment and see if you can detect one of the above problems.
Solving any of these problems may easily correct the yellowness.
In some cases, such as temperature related color changes, the problem may correct itself.
Sometimes deficiencies in fertilization can be corrected by checking the PH level or applying a form of iron which will help green up the leaves.
• Consider planting groundcovers where grass will not grow such as shady areas, around tree roots, and on steep slopes. Select plants based on the amount of sun or shade the site receives. Ground covers are a great way to keep your yard looking beautiful and preserve the soil in hard to grow areas.
• Mildew problems on roses, phlox, and lilac are likely to occur with the hot, humid, moist days and nights. Be sure to water only in the morning, and only on the ground around the plant, try not to get the foliage wet. If this and other fungal problems persist, we suggest using Infuse by Bonide, a systemic fungicide, and repeat the application every 10-14 days.
• Japanese beetles may be feeding heavily at this time. Brush the beetles into a bucket of soapy water held underneath foliage or branches. The use of Japanese beetle traps near your plants is not recommended. Studies show traps can attract more beetles, resulting in increased damage.
• Typically, July is an extremely hot month and proper mowing of your lawn is critical to help it survive the summer. “Mow it high and let it lie” should be your slogan. Cut your cool-season turf to a height of 3-4 inches and leave the clippings on the lawn where they will decompose naturally. Mow warm-season grasses, like zoysia and Bermuda, to a height of 3 inches.
1. Prepare garden space now for fall cool season vegetables. Work in composted manure or leafgro to add organic matter, remember to check PH which should be at 6.0 to 7.0. It’s time to begin thinking of fall vegetables. Seed for fall crops of broccoli, kale, turnip, and cauliflower should be sown in containers by the third to fourth week in July. Late crops of squash, beans, and cucumbers can be direct sown through the end of July.
• A reminder that frequent watering of container and patio plants as well as hanging baskets leeches the nutrients from the soil. You must fertilize to compensate for this loss. We suggest using Jack’s Classic fertilizer at half the dose rate every other time you water. Also, replace any soil that may have shrunk away with an organic compost such as Leafgro, or Composted Manure.
• Replenish the mulch in your beds where necessary to help keep the roots cool and maintain appropriate moisture levels. Remember this is the hottest and driest time of the year, and do not forget the winds are just as drying as the sun!
• Sow seed for fall transplants of broccoli, kale, turnip, and cauliflower in flats or containers by the third to fourth week in July. Late crops of squash, beans, and cucumbers can be direct sown into your garden through the end of July.
(Editor’s Note: Ken Morgan is the owner of Robin’s Nest Floral and Garden Center in Easton, Md.)