Ask the Garden Guru

Fruit Tree Planting in Winter

Dear Garden Guru,

I would like to plant fruit trees this winter but I live very close to the ocean, with lots of summer fog. Which fruit trees would you recommend for my microclimate?

Melissa in San Francisco

Hi Melissa,

For your foggy, coastal conditions consider Santa Rosa plum, Meyer Lemon, Persimmon, Asian Pear 21st Century, and Apricot.

For something more exotic, the Pineapple guava, Feijoa sellowiana, will work. You could also consider Blueberries!  Many of these will be available in January or by special order later in the season.

Lemon and herb recommendations for a SF Mission garden

Dear Garden Guru,

We live in the sunny but windy Mission district. Can you recommend a lemon tree and herbs that will work in this micro-climate? Thank you!

Donna in San Francisco

Hi Donna,

The Meyer lemon does very well in San Francisco.  The Eureka lemon will also grow but gives only one crop a year where the Meyer is known to produce almost year-round.  Herbs that will do in your neighborhood are rosemary, oregano, marjoram, thyme, and sage. These are woody plants and are not thirsty.  You can grow parsley, chervil, and savory but these “soft” herbs will require more water.

Do bulbs need to be refrigerated?

Dear Garden Guru,

I have dozens of bulbs for fall planting. I've learned I have to refrigerate the crocus, hyacinth and tulip bulbs, but I'm getting mixed messages on refrigerating daffodils in Northern California. Do daffodil bulbs need to be refrigerated in this area? Anything else I should or shouldn't refrigerate? (I know about not keeping fruits in the fridge with the bulbs.) Thanks!

Susannah in Kentfield

Hi Susannah,

You do not need to refrigerate Daffodils or Narcissus. Some people keep Paperwhite Narcissus in the refrigerator to “stall” sprouting so they can force the bulbs over a longer period of time. This is probably where you are getting a mixed message. While not necessary, some people like to chill their Freesias – it seems to make the stems sturdier.

Growing sweet peas

Dear Garden Guru,

When is the best time to plant Sweet Pea starts? When are they for sale? Thanks!

Lisa in Novato

Hi Lisa,

Alas, the best time to start sweet peas in your climate is in October. Planted in the fall, they develop strong root systems and then take off in the spring. Both seeds and starts are available. The second best time is in February. Our stores will have packs of tall-growing sweet peas available in a variety of colors.

Fall Foliage in the Bay Area

Dear Garden Guru,

Being from upstate New York, I really miss the fall colors. I recently traveled to Portland and noticed some trees there were alive with fall foliage. Can I grow such trees and enjoy the same bright colors every fall here in S.F.? And, if so, what are the bright yellow, red, reddish pink and orange trees I see. Also, what vine grows up the trees and turns red each fall?

Lee in San Francisco

Hi Lee,

San Francisco has a very mild climate and the degree of temperature fluctuation from night to day is very small. All those brightly colored trees require a change in weather (colder than what we have) to start the coloring process (along with a bunch of other factors that affect their biochemistry). Those multi-hued trees you see are Chinese Pistache and they require the least amount of chill to get going. Ornamental Pear and Liquidamber are two other trees for you to consider. Our customer service team members can help find them for you at any Sloat location.

The vine you mention is Boston Ivy. There are two types available Partheocissus tricuspidata (3 lobed leaves-the classic) and Parthenocissus quinquefolia (5 lobed leaves). Both will change color in San Francisco, albeit later than the surrounding counties.

I hope this helps you find some fall colors.

Aphids on succulents: help!

Dear Garden Guru,

What is the best way to get rid of aphids from my succulents? They are only damaging a couple varieties but the ones damaged are pretty bad. Thanks

Hunter in San Francisco

Hi Hunter,

You can control the aphids with Bonide All Seasons Oil. This non-toxic oil spray will smother both eggs and adults. Water your plants prior to spraying and apply when temperatures are 75 degrees or less.

Waterwise Privacy Screens

Dear Garden Guru,

I am looking for a waterwise, evergreen shrub that will grow 10ft tall to provide a privacy screen. Any suggestions?

Carin in Novato

Hi Carin,

Hello! Good candidates for your purpose are:

  • Podocarpus (all species and varieties: gracillior, macrophyllus, Icee Blue)
  • Dodonaea ‘Atropurpurea’, the Hopseed
  • Rhamnus alaternus and Rhamnus John Edwards
  • Pittosporum tenuifolium

 

Fungus gnats on my ficus

Dear Garden Guru,

I have some little black flies in my apartment and today noticed there were more of them gathering around my ficus plant...the soil in the pot. Without using chemicals, can you tell me how to rid my home of this pestilence! Thanks.

Nina in San Francisco

Hi Nina,

Those little buzzing pests are fungus gnats. They become a problem when houseplants (or greenhouse plants) are over-watered or when the soil stays constantly moist. Overly moist soil is more relevant to the gnats indoors because the temperatures stay warm. The adult gnats lay eggs in the soil. The larvae hatch and begin to feed on the decaying organic matter of the soil (and can sometimes harm roots if their numbers are great). They pupate and then emerge as the annoying gnats to start the cycle again.
The cycle can be broken if the soil is kept drier, allowing more time between watering. Repotting a plant into fresh soil will also help. There is also a product called Gnat Exterminator. They are beneficial nematodes (microscopic soil dwelling “worms”) that prey on the gnat larvae. They are applied as a spray to the infected foliage. Sloat also carries a miniature sticky trap, called Gnat Sticks that can be placed in the pot to trap the adult gnats.

Help with Gophers!

Dear Garden Guru,

Gophers have invaded our yard – there are holes everywhere! How does one get rid of them safely and not harm other animals and birds?

Deborah in Pacifica

Hi Deborah,

Start by using a repellent like Bonide Mole Max (it also works for gophers ).  This is a castor oil-based repellent that is not harmful to animals or birds. Take extra care to apply more heavily around holes. This granular formula is easier to apply than a liquid spray. Apply the repellent gradually towards the direction you want them to leave the property, in other words, leave them a way to get out. Applying the repellent to the whole space at once will just “trap” them there. If it is really very bad, you might consider a gopher removal/trapping service such as Smith’s Pest Management which focuses on trapping over poisoning.

Additional notes:

 

Tomato plant troubleshooting

Dear Garden Guru,

My tomato plants always look beautiful when I get them in the ground. I water and fertilize and then right after the plants flower they turn yellow and spindly and they don't fruit very well. What am I doing wrong?

Liz in San Bruno

Hi Liz,

Yellow and spindly tomatoes don’t fruit that well do they? Believe it or
not, I suspect that you are loving your plants too much. Over watering
tomatoes will wash away all the nutrients you so lovingly applied, it also
reduces needed oxygen in root zone and makes the plant susceptible to
disease. Your plants should be deep watered 2 to 3 times a week. If the
plant is seen wilting in the middle of the day, ignore it. Tomatoes will
close their stomas in the heat of the day to prevent water loss by
transpiration. They will perk right back up by late afternoon. If the plants
look droopy in the morning, they need water. Too shady a location will also
cause plants to be spindly but you usually see that effect immediately. If
the leaves are showing some signs of browning, your plants may have
Verticillium or Fusarium wilt. These are soil borne pathogens and there is
no chemical control available. Warm and humid conditions will hasten the
onset of wilt. It is highly recommended that you plant tomatoes labeled
with “VF” (Verticillium/Fusarium) on the label as these are resistant
varieties. Should there be an “N”, that means resistant to root knot
nematodes. Hope this helps for this year’s crop!

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