Horticulture Guy

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. 

Q. We have a Small Leaf Linden tree at our curbside.  It is quite large. 10 years ago, when it was pruned, the leader was cut.  Since then, it has grown into a very huge, very full mushroom shape. 3 years ago, we had it pruned by an expert. Wonderful job.  However, all summer long, small dead branches kept falling off into our driveway.  It is overgrown again and must be pruned again. Hubby wants it pruned and cut way back on the sides and top to make it smaller.  Please advise us for the best time of the year to have it pruned.  Thank you. G. Davis - Philadelphia, PA

A.  With the loss of the leader you now have a large shrub on a trunk.  I am not sure if the person you had prune the tree mentioned about trying to retrain another branch to become a leader and give the tree back its pyramidal shape. This is not essential in this case since the Little Leaf Linden (Tila cordata) can be pruned like a hedge.  Lindens have a tendency to bleed sap if pruned around its growth spurt in spring so avoid late winter through spring for pruning.

Q. I’ve heard in the past. You only have about 15 seconds to make your cuts while grafting, and connect the two together…is this true? thank You for any info.  Scot Rabosky - Cape Cod, MA

A.  Maybe if you are grafting in the desert.  The truth to this is that you do not want the exposed cuts to dry out at all.  This is dependent on the relative humidity of where you are working.  There is no magic number of seconds.  Just as critical is that the when the grafting is complete that you immediately cover the union with tape or grafting wax.  You also have to make sure that the rootstock and scion are in the proper physiological state and the cambial regions must be placed in intimate contact and must be compatible.

Q. I loved the video on planting elephant ears. I have mine in a big clay pot on the patio but need to know how to care for it. So I dig it up after the frost and keep it in a cool dry place but do I separate any new thingabobbers from it now or when I get ready to plant it next spring. Or can I just leave it in the pot for winter. We have some below 0 temps here in Southwest Va. so I don’t want it to freeze on me. Thanks Janet Tester - Tazewell, VA

A. Thanks Janet. Glad you enjoyed my video segment on Elephant Ears (Colocasia esculentum). You can over-winter the elephant ears either way. I usually just pull mine into the sunroom and they grow slowly during the winter. I slow down watering and reduce fertilization as well. If you have a very sunny window where it could fit this could be an option. I think it is easier to overwinter them in their pots and if you want to repot them do it in the spring when you are ready to take them out of dormancy. They key if you put them in a cool, dry, dark place is to make sure the soil in the pots are dry as well. The Elephant Ears have a tendency to rot if they are kept to wet in storage.

Q. I planted 3 Angel Lace Hydrangeas in 2005.  They have not bloomed, and I’ve found that they are hardy to zone 6 - I’m in zone 5.  Is this the reason that they haven’t bloomed?  They are green and healthy looking and have probably doubled in size since planting.  Can you give some advice on what to do with them? Erin - Pittsburgh, PA

A. This Lacecap Hydrangea is botanically from Hydrangea macrophylla and therefore is a hydrangea that blooms on previous season’s growth.  What will likely happen with your hydrangea is that although it may survive your winters you will loose the flowers on the old wood and it will not bloom, at least not regularly.  Not every year provides a zone-defining winter and so some years you may have flowers.  You may consider providing additional protection for the winter to protect the old wood.  Building a chicken wire cage around the shrub and filling it with leaves or straw would provide this kind of protection.  Needless to say you would also want to make sure you prune your hydrangeas after they bloom and not wait until later in the season.

Q. When is it safe to plant bleeding heart .I received a plant but know nothing about when I can put it in my garden. Thank you for any advice you can give me.  Christina Mulac - Louisville, Kentucky

A.  Bleeding Heart (Dicentra spectabilis) is a hardy perennial in the continental US.  Hardy means it can survive the coldest temperatures in the winter and perennial means it comes up multiple years (as in perennially).  Like other hardy perennials they can be sown in the spring or in the fall.  If you bought the plants as dormant roots then plant them as soon as you can work the soil.  This means waiting until frost leaves the soil and the soil dries out sufficiently.  This prevents damage to the soil structure.  To tell if the soil has dried out sufficiently take a hand full and squeeze it together lightly into a ball.  Then drop it to the soil surface from about 18 inches.  If the ball breaks apart the soil is dry enough to work.  If it stays in a firm ball then you should wait.  If the plant is grown in a container it can also be planted as soon as the soil is ready except if the plant was grown in a protected structure, like an greenhouse or coldframe.  If it was bought at a garden center you can ask them if the plant has been outdoors unprotected for at least two weeks.  If so then plant away! Bleeding heart prefers a partly shady spot - especially when grown in an area with hot summers like you can get in Louisville. 

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