A question I am frequently asked is how to change a hydrangea bloom color. I would say the majority I see are blue. As many gardeners know, you can change the color to pink or somewhere in-between. Everyone has their personal preference.
All you have to do to change the color of the bloom is change the soil pH. Flowers will become pink in alkaline soils and blue in acidic soils. To change the color from blue to pink, apply a small amount of hydrated lime under the plant (about ½ cup for a 3-foot plant).
Dolomitic (or agricultural) lime can be used, but the results are not as immediate or dramatic. If you use dolomitic lime, the more finely ground the lime, the quicker the pH will change. Look at the screen analysis on the bag. You want 70 percent or greater to pass through a 100 mesh screen. Most pelleted lime is of higher quality. Don’t be fooled by the size of the pellets. It has been screened, then pelletized for ease of use. You can also use wood ashes to raise the soil pH. They contain fairly high amounts of potassium and calcium. They are not effective as lime but with repeated use, they can drastically raise the pH of a soil, especially in sandy soil.
What if you have pink hydrangeas and want to turn them blue? Spread a small amount of wettable sulfur (about ¼ cup for a 3-foot plant) or aluminum sulfate (about 1 1/2 cups per 3-foot plant). Aluminum sulfate is faster, but be careful because too much sulfur can damage the plant.
Planting a shade tree
Does your deck, patio or porch get too much sun? Now is the time to make a note on how to properly place a shade tree to block the sun. Summer is not the best time for planting trees, but it is ideal for deciding where they should go.
During the next few weekends, track the path of the sun across the sky and make notes of the time of day when it reaches the area you think needs shade. Observe when the sun passes below the horizon or into the neighboring houses and trees. From this information, decide where would be the ideal place that would provide the most shade.
When cooler conditions of fall arrive, you will have already located the ideal spot and it will then be the proper time to plant a tree.
General August gardening tips
Clean up fallen diseased leaves on various ornamentals, as they can harbor disease and insects if allowed to remain on the ground.
Slugs are always a problem when we have an abundance of rain. You can use grapefruit rinds as slug traps. Place them cut side down in the garden. Slugs will hide and sometimes die under the rinds. Simply turn them over, remove the slugs (with a disposable glove) and put them back. The rinds take a long time to decompose so they can be reused.
You can spruce up geraniums that might have lost its leaves because of Botrytis (gray mold), which makes them look a bit pathetic at this time of the year, especially with a lot of rain. This is especially true if tall “scraggly” stems are all that remain. Prune tall stems back to a point just above the short side shoot. This will force the side shoots into new growth.
Fall is a great time to divide perennials for next year’s garden. By planting in the fall, your plants do not endure the stressful summer heat and have time to form sufficient root systems before the onset of winter dormancy.
Have your butter beans or string beans been dropping from the plant this summer? Unfortunately, these vegetables shed pods whenever stress comes along. This would include dry or hot weather, poor fertility or even too much water. Also, watch for stink bugs, kudzu bugs and other plant bugs which cause beans to shed.