Why Won't mY hYDRANGEA bLOOM?
About The Problem
There are a number of reasons why hydrangeas won’t bloom properly. The main reasons are incorrect pruning technique, inadequate or improper fertilization, or damage due to cold weather.
One main cause of hydrangeas not blooming or blooming poorly is incorrect pruning technique. Correct pruning of Hydrangea Macrophylla, (one the the most common types of hydrangeas and includes the Big Leaf Hydrangeas) is most commonly done by dead- heading the plants toward the end of the flowering season, which involves removal of the dead blossoms and, at the most, the top 2-4″ inches of the stem. In the Webster, NY area, this can be done any time from the middle of October to early May the following year. If done very carefully, hedge trimmers can be used to cut off the flowers and the top section of stem, but hand loppers can also be used. If done in the spring, hand loppers can be used to selectively remove dead or weakened stems in addition to deadheading the plants. The goal of pruning hydrangeas is threefold: deadheading the hydrangea plants removes dead flowers that can harbor powdery mildew and other diseases; it encourage growth and blooming the following year, and it neatens the appearance of the hydrangeas and helps to control the size of the plants to some extent.
Most hydrangeas bloom either entirely on wood grown the previous year, or on a combination of both new and old wood. One of the most common mistakes in pruning that can lead to hydrangeas not blooming is pruning the plants back too far, thus removing nearly all the flower buds. The correct term for this type of drastic pruning is “rejuvenation pruning”. Generally, the only time that hydrangea plants should be pruned down to ground level is if the size of the plants is far too large, or the hydrangea plant is weak and pruning back drastically is a last attempt to rejuvenate the plant. Pruning plants back this far should be reserved for only the most extreme situations, as the plants will take at least one year to recover and begin blooming regularly.
Another cause of hydrangeas not blooming is inadequate or improper fertilization. Like all blooming plants, hydrangeas need phosphorus and potassium. Phosphorus is especially associated with flowering in plants. A fertilizer rich in phosphorus and potassium should be applied to the hydrangeas. Too much nitrogen can lead to excessive green growth and very minimal blooming. Also, if large quantities of nitrogen are applied too late in the season, it can lead the plants entering dormancy later, which can lead to poor cold tolerance. Flower color in hydrangeas is largely determined by soil pH; a lower soil pH (acidic) results in a darker coloration more towards the blue color spectrum, whereas a higher pH (alkaline) results in a lighter coloration more towards the pink color spectrum. Hydrangeas prefer to have acidic soil, so fertilizing the plants with aluminum sulfate is a good way to reduce soil pH. A good general fertilization program for hydrangeas involves fertilizing the plants twice a year with an acidic balanced fertilizer, such as Holly Tone, starting around the middle of April for the first application, and again in October for the second application.
Another main cause of hydrangeas not blooming is cold damage. Just like fruit trees can loose their blossoms from a late frost, thus impacting the fruit crop, hydrangeas can have their blossom buds freeze due to a late frost. While not easily preventable, cold damage can explain why some years, despite otherwise proper care, hydrangeas do not bloom normally.
About Paul's Landscaping of NY, LLC
At Paul’s Landscaping of NY, LLC we specialize in providing exceptionally high quality landscape design, installation, and maintenance services to the Webster, NY area. If you need your hydrangeas properly pruned and fertilized, or if you need any other landscaping work done, request an estimate today.