Ask the Garden Guru

The Garden Guru  is on vacation. Please check back October 18th.

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Using bamboo as a yard screen

Dear Garden Guru,

I want to grow bamboo in my backyard to prevent my neighbor from looking into my yard. Can you suggest a type that will only grow about 10 ft high and where i may be able to purchase it. Thanks.

Renee in San Francisco

Hi Renee,

The Bambusa variety ‘Golden Goddess’ will fulfill your needs. Not only does not get much taller than 10′, it also is a clumping type bamboo. The clumping types do not aggressively spread through the garden. There are currently none at our stores in San Francisco, but we do have them in Marin at our Novato store. We can transfer them to the store of your choice or they would be happy to place an order for you.

Blood orange tree doesn't produce fruit

Dear Garden Guru,

I have a blood orange tree in a container. The first 2 years the tree produced fruit. Last year, the tree had healthy leaf growth but no flowers at all. What do you think the problem could be?

Barbara in Kentfield

Hi Barbara,

The Blood Orange does not respond well to great fluctuations in humidity. Flowers do not set well when the air is very dry. They dry up too quickly and die before being pollinated. I suspect that last year’s extremely dry weather was the cause. Other sensitive citrus such as Mandarin and Meyer lemon had the same trouble. Your tree should be getting ready to flower again this spring. Thankfully, we have had some rain and water evaporating from the soil will increase the humidity around your tree. When it is hot and dry in the spring, you may want to hose the plant down in the mornings to prevent flower loss.

Fruit tree questions answered

Dear Garden Guru,

I live in SF - Richmond district near Park Presidio Blvd. What kind of fruit tree would you recommend for this area other than apple and pear which I already have? Also, I have Winter Nellie pear, D'Anjou pear and Red Delicious apple trees in Richmond district of SF. When and what should I spray the trees. 2008 I had caterpillars on the pear trees eating up all the leaves and would like to avoid them, if possible.

Jane in San Francisco

Hi Jane,

Dear Jane,

If you want another type of deciduous fruit tree consider a Santa Rosa or Beauty plum. Apricots can also be considered if your yard is really warm and sunny. Of course, all types of Citrus will also do well for you : Trovita orange, lemons, limes and Mandarins.

You can spray the trees now and again in mid February with Kop R Spray to prevent diseases such as powdery mildew and scab. To treat for caterpillar, wait until 3/4 petal fall (when 3/4 of the flower petals have dropped off the tree). By then, the young leaves will be pushing. Spray with BT caterpillar killer at monthly intervals or after heavy spring rain. This is a harmless spray to non target insects such as bees and other wildlife.

Deer resistant trees

Dear Garden Guru,

I am looking for a tree to plant in my front yard that is deer resistant yet Japonesque in feeling. It will be near a Japanese maple. Is there a cherry blossom like tree that you could recommend? Ideally it would be great if it doesn't grow more than 10 to 15 feet tall. Thank you!

Natalie in Larkspur

Hi Natalie,

Unfortunately, the deer will nibble on young flowering cherry and plum. Have you considered a Magnolia soulangiana (Saucer Magnolia)? They are quite dramatic in flower. Other small trees that would fit your theme are Laburnum ‘Vossi’ (Golden Chain tree), and Cercis occidentalis (Western Redbud). You might even consider a Southern indica Azalea patio tree. If you decide on the flowering cherry, Snow Fountain or Pendula are best. You will need to protect the trunks by caging them with chicken wire.

Growing lilacs in containers

Dear Garden Guru,

I would like to plant a lilac tree in a container in the front of my home. Facing NW. Which lilac? How big a container? Planting medium? Or am I just dreaming.

Linda in Daly City

Hi Linda,

There may not be enough sun with that exposure to allow the lilac to bloom well. Should you decide to try, a Korean lilac such as Miss Kim will be the most successful. The container you plant in should be a minimum of 4″ wider than the size you buy. You will want soil that drains readily. Sloat Potting soil will do the job.

Fruit tree myths

Dear Garden Guru,

Myth or truth? Some people say NOT to eat first year fruit off the tree. Or is it just that the first year fruit will not be as good and delicious? Or should the first year fruit just be left on the tree until it falls off? I noticed the instructions for the blueberry plants that I just bought ...it notes to pick the flowers off the first year in order to have better berries by the second year. Question is really about fruits like apples, plums, and pears in their first bearing year. Thanks...

Jane in San Francisco

Hi Jane,

A little bit of both. Myth is that the first year fruits would not be as delicious. Truth is that if a young bearing tree does not have to use energy to produce and ripen its fruits, it will grow that much stronger and fully develop its young body. It is difficult not to allow the first fruits from developing just as it is difficult for us to thin the fruits on a tree. Thinning fruits gives you bigger and more evenly ripened mature fruit. We as home gardeners want every fruit to mature. This can be bad if branches are heavily laden. Too much fruit will break limbs. And you know what, the blueberries in 2g cans are not first year plants. You can let them flower and fruit.

When is the best time to spray apricot trees with dormant spray?

Dear Garden Guru,

When should I spray my apricot tree with dormant spray? It really produced in 2008 but we had only 8 apricots in 2009.

Barbara in San Rafael

Hi Barbara,

What affects Apricot production is weather and a phenomenon called alternate bearing. Late winter and spring rains destroy the early flowers of apricots. The rains also prevent the bees from coming out to pollinate. Alternate bearing provides another whammy, for some reason some fruits produce a bumper crop one year and then produce a mere handful of fruits the following year. I am betting that 2010 will be a good year for you (if we have sunshine while your tree is in flower!). The time to begin dormant spraying the apricot is now, in late October/early November, again in December and once again in late January. DO NOT use a sulfur spray such as “Lime Sulphur” on apricots. Use a copper spray instead (Kop R Spray, EB Stone Copper spray).

Christmas Tree Alternatives

Dear Garden Guru,

I want to have a green Christmas this year and am looking for an alternative to the cut or plastic Christmas tree. Do you have any suggestions? Ideally I would like a potted bush/tree that I can leave outdoors all year and then bring in for the holidays.

Marisol in San Jose

Hi Marisol,

Sloat carries a line of plants to be used as living Christmas trees. The most common type is the Alberta Spruce. It grows as a narrow cone. We also carry some smaller Spruce in 2 gallon and 5 gallon cans. You can choose from Blue Spruce or Norway spruce. These plants grow slowly, can stay in a container and will not lose their shape over the years. Pines are also available but they are hard to maintain year after year in a container. These you would want to plant outside. Rosemary and Ivy trained as cone shapes are also available. We have also seen people using Ficus benjamina trees for Christmas!

Overwatering a fig tree

Dear Garden Guru,

I have a figtree (ficus) that I bought as an indoor plant, it was doing well but now the leaves are dropping off, & turning black /brown in various parts. Please help, I love the tree.

Lois in San Francisco

Hi Lois,

It sounds like over watering damage. The first signs of over watering are white/clear secretions from the two glands at the bottom of the leaf next to the middle vein. The next step is odema. The cells overfill, rupture, and the resulting dead tissue turns brown/black followed by leaf abscission. Though evergreen, Ficus still will go into periods of reduced growth, mostly in the fall and winter as the hours of daylight dwindle. They will require less water during these times of year.

When watering your Ficus, be sure to water thoroughly. Add enough water so that the container drains (this also keeps mineral salts from building up in the soil). Remove any water standing in the saucer after about 15 minutes. You do not want your tree to sit in standing water. Allow the soil to become fairly dry before watering again (this means soil is dry 2″ below the surface.) Depending on the size of the tree, this can be once a week or every other week, even longer in the winter months if the room it is kept in is cool.

You may want to fertilize with a mild food such as Maxsea 16-16-16, but only use it half strength during the winter. Be patient as I have seen Ficus almost completely defoliated come back strong and healthy.

Ideal trees for small San Francisco garden spaces

Dear Garden Guru,

Like most San Franciscans, my garden space is small and close to the house. I'm looking for a tree that will not exceed 15 feet or so, and can tolerate drought as well as the wind and fog in the city. Any suggestions?

Jennifer in San Francisco

Hi Jennifer,

The Arbutus Marina and the Olive (fruitless or otherwise) are 2 trees that satisfy your requirements. There are also shrubs that have been trained as a “standard”. That is they have a single trunk and a head. A standard form of Oleander, Dodonaea (Hopseed), and Pittosporum tenuifolium will also fill the bill.

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