Horticulture Guy"Live Long and Garden" – Peter Punzi

Q. Interested in advice on planting mophead hydrangea in my zone 6 location. The area I am planting receives sun from 12N on. Soil is clay & will slopes away from plants. I am asking before I buy as I need approximately 15 bushes to fill in space & don’t want to make the investment if it is a losing battle. Please advise, if possible. Tonya Amber – Vanderbilt, Pa

A. The mopheads fall under Hydrangea macrophylla and from what I can tell your location is just a little too cold for regular blooming as the plants may freeze to the ground in many years in the west of Pennsylvania. This would kill off the flower buds. You would have beautiful plants but not any blooms. If you are interested in having a hydrangea you may want to try the Peegee Hydrangea (H. paniculata ‘Grandiflora’) which would handle your winters a little better. Be sure to add some organic matter (like compost) to the soil before planting to help enrich and aerate your clay soil.

Q. I received a rose bush for Mother’s Day and kept it in a clay pot on the deck because it is the only sunny spot. Will it survive the winter in a clay pot. Any special precautions? Also, it has had black leaf problem. Will that kill it this winter? Thanks. Maureen – Holmdel NJ

A. It depends how close the pot is to the house. There is always a chance that a clay pot will break if there are freezes and thaws. Unless the clay pot is sealed the trapped water in the clay pot expands as it freezes and can crack the pot. Also see if you can find the USDA hardiness zone of your rose. It may be printed on the label that came with the plant. You can leave plants in containers safely if they are rated for two zones lower than your zone. I would guess you are at a zone 7 (Having grown up in NJ I know you are near the shore). That means a plant rated to zone 5 could be grown in a pot. The alternative is to find a sunny location in the yard and sink the pot in a hole until spring. The black spot disease you have on the roses won’t be active during the winter but the overwintering spores may attack your rose again in the spring. Once the plant is actively growing again can use organic neem oil to control the blackspot.

Q. It’s my first winter in my new “established” house. Lot’s of free standing bushes which I know all flower in different times of the summer, don’t know what they are but they have become overgrown and I have no idea when to prune them or how much.  There are forsythia, taller then a person and the two other major bush growths are 15 to 20 feet high and I would like to get them down to about 5 ft or so any suggestions, based on the info I have provided?  Thanks Sandy – Vernon CT

Without knowing what the other species of shrubs are it is difficult to tell you how to prune them and what type of pruning (e.g. drastic) they will tolerate. Many shrubs have their own genetic predispositions.  I can say that if they are flowering shrubs and you do not wish to loose a season of blooms you will want to prune early blooming shrubs immediately after they bloom since they bloom on old wood where flower buds form.  Later blooming shrubs have a larger pruning period, which includes the dormant season, since the flowers will develop on new season’s growth.  Your forsythia will take some heavy but judicious pruning.  It flower buds grow on old season growth so take that into consideration when pruning.  I would suggest either finding a book on pruning shrubs or checking out the University of Connecticut’s Home and Garden Education Center website: http://www.ladybug.uconn.edu/ for more information.
 

Q. I own a Dracaena Mass Cane.  It stays indoors in the winter and is brought out in a screen house in the summer months.  It enjoys being outside so much that it now is taller than ceiling height of the house. Question: Can the top be cut back?  It is about 9 ft. tall now.  If I cut it back to say 4 ft. will this kill the tree?  Is there a certain time of the year this should be done? Tony R. – Valley Stream, NY

A.   Yes in theory the canes can be cut back on Mass Cane (Dracaena fragrans ‘Massangeana’) since the plant you now own came from a stem cutting taken from a mother plant.  So in theory you should be able to remove the stem and have new growth form below the cuts.  In theory you could also put rooting powder on the revomed stems, or sections of those stems and start new plants (stripping the leaves off of them when they are removed.  In tropical regions like Costa Rica where they are harvested I believe they propagate all year.  But in NY I would wait until the weather is a little closer to “tropical” and do it in the spring the late spring or early summer.  I have never performed this operation on a Mass Cane myself so this is all theoretical.  Since most plants have multiple canes I would suggest testing one cane this summer and see how it responds.  If you get new growth then you can comfortably prune back the other canes.