Scheduled Ask Extension System Maintentance This Week

Maintenance is scheduled for this Thursday, March 4th from 11:00PM EST until Friday, March 5th 4:00AM EST. Ask Extension will not be accessible during this time.

KNOCKOUT ROSES #168409 - Ask Extension

Knowledgebase

KNOCKOUT ROSES #168409

Asked February 28, 2014, 11:29 AM EST

WE LIVE IN WESTERN KENTUCKY AND HAD A LOT OF RAIN LAST SUMMER. I TRIMMED ALL MY ROSES IN THE SPRING, BUT MY ROSES NEVER BLOOMED MUCH OR HAD MUCH GROWTH. EVERYONE SAID THEY GOT TOO MUCH RAIN.  I AM HESITANT ABOUT TRIMMING THEM BACK AGAIN THIS YEAR. WHAT WOULD YOU RECOMMEND

Marshall County Kentucky

Expert Response

The knockout rose is a hardy selection and I congratulate you on your choice of it.  Though it may not seem the case when you have had less than expected growth and bloom the year before, pruning will be vital to the health of your roses.  If the rose is allowed to stay to dense, then you are more likely to have problems with fungal diseases.  If you have not done so on your previous pruning sessions, you should place a drop of white glue on a cut on a stem larger than 1/4 of an inch to reduce the chance of borers infesting the cane later.  It will be vital to use sharp pruning shears, since jagged cuts make future problems more likely.  
In relation to the excessive rain, your nutrients were likely washed away resulting in your knockout's lackluster response.  Most of the rose fertilizers are a low nitrogen blend such as 5-10-5 with the first number representing the content of Nitrogen, the second the content of Phosphorus and the third content of Potassium.  It is safe, however, to use 8-8-8, 10-10-10 or 12-12-12 on your roses.  It is recommended to fertilize in spring after the danger of frost has passed and every four to six weeks during the growing season.  
In summary, I recommend pruning your roses and making sure to fertilize regularly.  My roses always liked a treat of banana peels placed at the base.  It gave them a boost of potassium and perked them up!  The information I gave you in this answer (minus the banana peel treat) is taken from the University of Kentucky publication ID-118 on Roses.  I am attaching a link to that publication to this response.  I hope this helps and that you will continue to use Ask an Expert for your gardening concerns.

http://www2.ca.uky.edu/agc/pubs/id/id118/id118.pdf
Stephanie Harper Replied February 28, 2014, 2:23 PM EST

Loading ...