Rooftop patio needs vines for privacy and beauty

QUESTION: "We live in San Francisco on the roof top of a 10 story condo building. Our unit features a 16'x30' paved patio, which flanks our neighbor's patio, separated by a steel 'privacy' fence with holes. We are looking for suggestions for vines or other plants that will survive in containers, endure the SF weather patterns, not drop their leaves, and provide adequate privacy from the neighbors - that is, grow to 4 feet high and spread horizontally. The area where we need the plants faces north and gets sun in the afternoon. Any suggestions?" -- Laura and Bill
ANSWER: You might consider climbing plants such as Carolina Jessamine, creeping fig, bougainvillea, climbing roses, climbing hydrangea, clematis and trumpet vine for the fence itself, then add some containers of smaller growing plants (up to 4 feet in height with some variation in color and size) such as bamboo, agave and palms.
Most of the vine plants listed above bloom. The evergreens are the Carolina Jessamine and evergreen varieties of the clematis. The other vine varieties will probably still go dormant even with San Francisco's mild weather.
QUESTION: "I have ten cedar Green Giant quartz sized plants that have been in the ground since September and are beginning to look like they need some fertilizer. We had several days of frost and cold weather the last couple of weeks and that's when their color changed. I have given them a deep watering about every two weeks.
"What type of fertilizer should I use on the Green Giants and also how often should I fertilizer them to ensure a fast growth rate? They were very healthy plants when I received them and want to keep them that way!" - Nancy Melia
ANSWER: I would wait just about a month before you fertilize. To green them back up and begin to put on more foliage you will need a fertilizer with a higher nitrogen content then the other elements. I would use a 20-10-10 or equivalent to begin with, if using oil based fertilizer. Take about one half cup and circle it around the base about 6 to 12 inches from the stem or trunk of the tree.
If you go with organic, which is my preference, use either fish emollient or rich compost. Hope this helps and keep me informed. I should add that it is natural for the trees to have brownish or purple tinge to them after a cold snap.
QUESTION: "I live in Maryland where the temperatures for the last two months were in the 50's and 60's. Now near we are finally having winter weather (20 - 30 degrees). However, my tulips and crocus are about four inches above ground. Is there anything I can do to protect them from the now freezing temperatures - or do I just let them go and hope for the best?
"I also noticed that some of my dogwood trees that I planted last year are beginning to get buds on them. What will this weird weather do to them? Thanks for any assistance you can give me." - Pam Crawmer
ANSWER: This is happening all over and there just isn't a lot you can do to prevent the bulbs from popping up early when the weather is as warm as it as been in many places this winter.
You can try covering them in a thick layer (3-4 inches) of mulch or taking a heavy cover, such as a tarp, and covering them, especially during the cold evenings that we are currently having. This might help to save some of your bulbs. Once they come up they die back and don't generally produce any regrowth in the same spring. As far as they are concerned, they did their thing.
If you can't do the mulch or tarp, dig some up and put them in pots for enjoying inside. They should still grow and run their course indoors where the temps are much warmer.
The same thing happens with trees or shrubs that are spring flowering: if they flower too early and are hit by cold weather knocking off the blooms, they will not bloom again this spring. Leaves will come out, but no blooms.
The Plant Man is here to help. Send your questions about trees, shrubs and landscaping to and for resources and additional information, or to subscribe to Steve's free e-mailed newsletter, visit

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