Good afternoon and thanks for your time. We moved in to our house in Burlington 4 years ago, and during that spring, I planted two blushing bride hydrangeas (don’t remember the latin name) in a small garden in front of our house (see picture). The garden is on the west side of our house, and because we have large maples on our front lawn, the garden only gets sun from about 5 pm to sundown, with occasional periods before that where the sun breaks through gaps in the tree leaves. I don’t know what has been done in the past to the soil but I haven’t modified it with anything since moving in. I did add cedar mulch 2 years ago to keep moisture in. This year I have been watering them every other day with the soaker hose seen in the picture (there are spring perennials which are also in the garden but not seen here). The previous owner had been growing a cedar shrub in this location that I removed when we moved in.
So now to my question: as you can see, the plants are pretty small, and don’t seem to have grown in size since I brought them home from the nursery. Is there some fertilizer or additive I can try to increase the plant size, or did I just pick a bad spot (i.e. not enough sun) for these hydrangeas. If so, is there an alternative similar plant which you would recommend for this garden?
The botanical name of your Endless Summer Hydrangea is Hydrangea macrophylla ‘Blushing Bride’.
Hydrangeas prefer well-drained, moist soil, but not wet and thrive well in part shade location with a preference for the morning sun. In your case, with the end day sun, you have to be aware of watering your plant regularly. Water must penetrate about 2.0 to 2.5 cm into the soil when you stick your finger in the soil to see that it is wet. To maintain moisture longer you already added mulching, be sure the mulch does not touch the trunks. That can encourage disease. Keep up the regular watering through into fall, and be sure to give the plants a final thorough watering in late fall after they have gone dormant but before the ground freezes.
You indicated you’ve never added any fertilizer or compost in this area. I recommend you to add early summer a slow-release fertilizer with a high percentage of phosphorus (the middle number in the NPK ratio). Phosphorus is the element that encourages roots growth and bloom production. You must stop the fertilization in by the end of July. Next spring you would add organic compost or manure to boost your plant.
In case you really would like to put another shrub at the same place, there is an excellent Toronto Master Gardener Garden Guides available with ideas on shrubs and good advice on planting and caring for your specimen: