The end of August is not the time to fertilize roses, hydrangeas, fruit trees or shrubs. Feeding plants at the end of the growing season can stimulate new growth that can be burned by an early frost.
If you are looking for a fertilzing routine tailored to your specific conditions, a soil sample should be taken and the fertilizer and trace elements matched to the needs of your soil. Don't fertilize after August. Fall is the time for hydrangeas to begin preparing for dormancy.
For hydrangeas planted in ground.
For optimal growth, bloom production, and quality, fertilize three times: In early spring when plants are just leafing out. In early May to boost their flower production for summer. In late June/early July to help your plants finish the summer strong.
Don't apply fertilizer to any type of hydrangea after mid-August. You don't want to encourage late season growth that is more sensitive to winter damage. This is especially important for types of hydrangeas that set flower buds on the previous year's growth (old wood).
"If you want a longer stem, you can make a deeper cut as long as it is done before July or August when the plant begins forming buds for next year's flowers." For smooth hydrangeas, she suggests removing the faded flowers as soon as they fade to green to ensure a second flush of smaller flowers in the fall.
Avoid feeding hydrangeas after August, especially in regions with cold winters. A slow-release plant food works well. For best results, try Miracle-Gro® Shake 'n Feed® Flowering Trees & Shrubs Plant Food, which feeds for up to 3 months.
You'll find hydrangeas growing in hardiness Zones 3 to 7 as perennials. With flowers starting in spring and often last throughout summer into early fall, hydrangea flowers can be the foundation plant of your landscape.
Apply a slow-release chemical for shrubs and trees once a year. Depending on the variety, a balanced time-release fertilizer can be applied a few times a year, in spring and early fall. Take care not to apply too much fertilizer as it could burn the leaves.
The best time to deadhead is when the first set of blooms on your hydrangeas begin to turn brown and dry. Cut the stem below the flower head and just above the first set of leaves. For reblooming types, you can deadhead again when this second set begins to fade, but only through mid-August or so.
Oakleaf (H. quercifolia) and bigleaf hydrangea (H. macrophylla), including Nikko Blue and all the other pink- and blue-flowering cultivars, bloom from buds set the previous year. If they need pruning to maintain size or shape, do it in the summer, preferably before August.
But when to prune them? Prune fall blooming hydrangeas, or old wood bloomers, after they bloom in the summer. If you prune old wooded hydrangeas in fall, you are cutting off next seasons blooms. Summer blooming hydrangeas, or those that bloom on new wood, are pruned in the fall, after they stop blooming.
Reblooming hydrangeas flower on both new and old growth, meaning you can enjoy flowers from June until the first frost. They'll continue to bloom long after other flowering shrubs and perennials have stopped. Long lasting blooms of blue, violet, pink, white, or chartreuse add brilliant pops of color to any garden.
Deadhead After Flowers Die
"If you plant your hydrangeas in the right location and give them ample space to grow, the only trimming you should ever have to do is to remove the deadwood and dried blooms," Enfield explains. If you do this early enough, you may encourage the plant to set a second flush of blooms.
Many customers ask why their hydrangeas aren't blooming. The primary reasons hydrangeas don't bloom are incorrect pruning, bud damage due to winter and/or early spring weather, location and too much fertilizer.
If you over-fertilize, it can burn the root system of your hydrangea bushes and actually inhibit bloom production. For more tips on fertilizer and how to achieve big, beautiful blooms, please click here. My hydrangeas have brown dry spots on the leaves and brown petals on the bloom.
Also, when you do water, after a week or 10 days, water with a water soluble fertilizer such as Miracle Grow, Rapid Grow or Peters 20-20-20. Apply this water soluble fertilizer every second or third watering and see if the plant doesn't do better.
Some gardeners report success in turning their hydrangeas blue by applying coffee grounds to the soil. The coffee grounds make the soil more acidic, allowing the hydrangea to more easily absorb aluminum. In addition, fruit peels, lawn clippings, peat moss and pine needles, are thought to have a similar effect.
Water plants deeply prior to the heat event so that the root zone is well hydrated. Place mulch, such as bark, around plants to help keep in moisture. Avoid applying gravel or black-plastic mulches, which raise soil temperatures. Prior to planting, amend soil with organic matter.
To reduce the size of a hydrangea that blooms on new wood, cut off about one-third of each stem in late fall or early spring before it begins to leaf out. If your hydrangea blooms on old wood, prune right after it has bloomed when the flowers are fading.
Without going through the deadheading process, hydrangeas will not produce as many flowers and the few produced may not grow as big to their full potential.