I have just transplanted some perennials. Given that it is the end of August, is it too late to use transplant liquid?
Also, should I wait until spring to use evergreen fertilizer or can I fertilize now?
Thank you for contacting the Toronto Master Gardeners with your inquiry.
The best time to fertilize your evergreens is before new growth expands, around early April up to about mid-July. You should not fertilize your evergreens later than mid-July as this will stimulate new growth late in the season. This new growth will not have time to harden off before the temperature drops. Fertilizing Evergreens is an excellent article from the University of Minnesota.
Warm daytime temperatures, greater frequency of rain, shorter days, and cooler nights make fall the perfect time to transplant perennials. The key to transplanting in the fall is to plant early enough in the season to allow for proper root establishment, at least 3-4 weeks before a hard frost. You may wish to refer to one of our earlier posts: Transplanting perennials.
There are two schools of thoughts when it comes to utilizing phosphorous fertilizers- such as transplanter. It was originally believed that these high phosphate fertilizers assists newly planted plants to overcome any transplant shock, stimulates growth and increases the size of the plant, stimulates the growth of roots and stems and encourages flowering, and improves drought and disease resistance. Current research now suggests that “high levels of phosphorus are detrimental to mycorrhizal health and lower the rate of mycorrhizal infection of root systems” –The Myth of Phosphate Fertilizer
Anytime a perennial is transplanted it suffers some root loss which reduces the plants ability to uptake water. It is best when transplanting to cut back the above ground foliage by half. This allows the perennials to utilize their energy towards root production rather than into supplying water to the above ground growth. Applying 3-4″ of mulch around the transplant will also help with moisture retention and keeps the ground warmer, promoting root growth well into the late fall.