Ask the Garden Guru

Our Garden Guru is on vacation. Please check back with us with your question after July 4th. Thank you!

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!

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.

Mediterranean, bee-friendly fruit, vegetable and flower recommendations

Dear Garden Guru,

Can you recommend a list of Mediterranean climate tolerant herbs, fruits, veggies, and flowers which attract bees and hummingbirds? Any guidance will be much appreciated.

Wayne in San Francisco

Hi Wayne,

First tip is to take care of the soil. Don’t skip on the amendments that will help retain moisture and offer nutrition. Water regularly, especially the flowers and vegetables. Choose organic fertilizers that will not harm the beneficial soil organisms that help your plants’ root systems by improving nutrient uptake and guarding against disease. Actinovate is a wonderful supplement for any new garden plant.

Vegetables: peas, lettuces, chard, beets, cabbages, broccoli, mustard, spinach, carrots, radishes, kohlrabi, arugula (actually all your greens), in the summer- cherry tomatoes too. Herbs- parsley, cilantro, rosemary, chervil, savory, sage, thyme, oregano, marjoram

Fruits: raspberries, southern highbush blueberries, apples, pears, strawberries, loquat, pineapple guava, lemon, kumquat, Trovita orange

Flowers that attract beneficials and pollinators: white alyssum, cosmos, achillea, agastache, tulbaghia, Oenothera, Eriogonum (Buckwheat), Erigeron, Dianthus

Hummingbirds: Abutilon, Fuchsia, Agastache, Salvia greggii, Salvia clevelandii, Nasturtium, Delphinium

There is so much more, but this will get you started.

Planning an herb garden

Dear Garden Guru,

I am envisioning a small, kidney shaped herb garden right on our front lawn. I'm thinking about a raised bed, nothing too complicated, probably borders of some kind of stone or hardscape. What sort of herbs grow best in our climate? And can you offer any process insight in design?

Eric in San Francisco

Hi Eric,

Herbs that do well in your area are: Rosemary, Spanish Lavender, sage, parsley, Santolina, chive, and marjoram or oregano. Thyme and basil can be fickle. You may want to reconsider the kidney bean shape. A square or rectangle is more conducive to the classic herb knot and easier to work with. Choose plants that contrast in foliage color. After the size of the bed is decided, graph paper and colored pencils are very helpful. Each square could represent 1/4 ‘ so consider planting two 3″ pots per foot. Use a different colored pencil for each herb. In other words, 4 squares in a row would be colored the same. It might be worth looking at some of the DIY and HGTV links or calling our Design Department to schedule a consultation. The number is 388-3754.

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.

Growing vegetables this spring...

Dear Garden Guru,

I want to start growing vegetables, herbs and possibly fruit and I'm thinking of mainly using a green house since the weather in San Francisco can be unpredictable. Will the plants do well in a greenhouse and what fruits do well in San Francisco? Also, I read that I can grow potatoes from a potato I already have in my kitchen - will that way work or is it better to start from a seed? Thank you!

Rebecca in San Francisco

Hi Rebecca,

Your vegetables and herbs will do fine in a greenhouse. If the greenhouse will be completely enclosed (closed doors and windows), the flowering vegetables will not have access to pollinators. It will be necessary for you to act as the bee. This can be done by gently shaking the plants once in flower (tomatoes and peppers) or transferring pollen with a fine artist’s paint brush (squash, tomatoes, peppers). As for fruits, you can plant strawberries, apple, pear, southern highbush blueberries, persimmon, and plum with the greatest success.

As for potatoes, it is best to start from a “seed” potato. Most potatoes from the grocery have been treated to prevent sprouting. Organically grown, new potatoes can sometimes be used.

Herb garden and patio lemon questions

Dear Garden Guru,

As a chef, my edible garden is very important to me. I currently hold a SE exposed patio in SOMA with good light in the absence of fog. I grow many herbs and a dwarf Meyer lemon tree. Any recommendation to increase the crop and longevity of growing delicate herbs? Also, my lemon tree shows slightly yellowing leaves. I'm guessing lack of nitrogen and other trace minerals? The tree is producing several new flowers and buds. I'm worried the small tree cannot produce or support too many whole sized, ripe fruits. Shall I prune and reduce the crop size? Cheers.

Dave in San Francisco

Hi Dave,

For herbs: you may want to plant more of what you use most. I am thinking you mean things like Basil, parsley, chive, and thyme.  To encourage herbs to resprout more quickly after a pruning, feed them with a liquid fertilizer 1/2 strength every time you harvest. I like to plant herbs in 3’s. I rotate the harvest among them and it ensures I have enough when I need it.

It is common for citrus trees to yellow up, especially over the winter. We like the Growmore Citrus Growers blend which contains all the trace elements Citrus need. You can supplement with the E.B. Stone Citrus Food to provide more nitrogen. Citrus are notorious for producing more fruits than they possibly could support. The plant will thin itself when the young fruit is the size of green peas. There is no need to prune other than to shape.


Which fruit trees in the Richmond district?

Dear Garden Guru,

We are moving to the foggy Richmond District and would like to plant a fruit tree or two along the edge of our yard. What grows well in that area, and when should we plant? Thank you!

Lauren in SF

Hi Lauren,

You would do well with an Apple, such as Fuji or an Asian Pear (20th Century variety is self- fertile). You could also grow a European pear, but they do best in pairs (no pun intended). Lemons would also fare well. The best time to plant deciduous fruit trees is in January or February. You can plant citrus nearly year round.

Kiwi growing help

Dear Garden Guru,

I bought 2 kiwis (compatible male and female) three years ago and planted them in my sunny Mission district backyard. I pruned them back slightly this year as they haven't grown much and never flowered. Should I be fertilizing them? Do they need special care?

Dave in San Francisco

Hi Dave,

Good question! Kiwis can take up to 4 years to flower, sometimes up to 7 years before they get going. The wait is worth it though, Hopefully you will get flowers from both male and female plant this year for fruit production. Bear in mind the first fruit production is usually small and can take a few more years to build up to bigger yields. They are vigorous growers and can grow up to 40ft, so give plenty of room to grow in full sun. My recommendations on feeding are to top dress with Sloat Forest Mulch and feed with E.B. Stone Organics Fruit, Berry and Vine Food. I know of Kiwi vines growing in a community garden in the Soma area, and they have taken over an arbor and have produced fruit.  Hope this helps!

Meyer Lemon Tree advice

Dear Garden Guru,

I have a Meyer lemon tree the has blotchy yellowing leaves but only in one section of the tree. Could you tell me what it is and how to treat it?

James in SF

Hi James,

Your tree is showing signs of  a condition known as mesophyll collapse. It is caused by low humidity and drought conditions. It is not a disease so it cannot be treated with any spray. This is an affliction that the tree will grow out of IF a regular feeding and watering regimen begins in the spring. In addition to a citrus food fed every 6 weeks, a spring and fall supplement  of F.S.T ( iron, sulfur, zinc) will provide necessary micronutrients.

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