Ask the Garden Guru


Use the form at right to ask the Garden Guru a question.




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.

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.


Tomato plants

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!

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.

How to amend soil?

Dear Garden Guru,

We have your basic clay earth in our backyard. I want to amend the soil. What would you recommend I amend it with? Just regular planting mix that you sell? Or should I add lime or some other soil additives like chicken manure.....what is your secret recipe? And is it better than the Colonel's?

Bruce in Glen Park

Hi Bruce,

Forest Mulch Plus, Forest Mulch Plus, Forest Mulch Plus! This is a longer lasting blend of organic materials that also contains some chicken manure (not finger likkin’ good). This mixed with Gypsum will help break down and loosen the clay. Keep in mind that one application of any product will not change the soil indefinitely. You should get in the habit of applying the Forest Mulch Plus as a top-dressing twice a year to continue to work into the soil and help keep it from reverting to it’s natural (and heavy) state.

Rose Pruning

Dear Garden Guru,

I'm pruning my roses. Some are very tall. Is it true that if a branch of a rose bush has no thorns, it is a sucker? I've tried to get down to the bottom of the bush to see if the branch is coming from the base of the bush or from the ground. I can't always identify so I was wondering if the absence of thorns makes a difference. Any help would be appreciated. THANKS!!

Lorraine in Walnut Creek

Hi Lorraine,

Unfortunately, the lack of thorns does not indicate whether you have a sucker or a cane.  Many rose bushes will throw almost thornless canes occasionally that produce an umbel of flowers. They are difficult to prune in that they don’t always have a well oriented leaf bud scar to make a cut above.  You really do have to see if the origin is coming from beneath the bud union or the root zone. These thornless canes are often skinnier than there thorny sisters which makes it even harder to tell.  You won’t be hurting anything if you feel you must remove it just to be sure.

How to make Wisteria bloom

Dear Garden Guru,

I have a wisteria vine. It barely blooms and produces just leaves. I want to thin it out to bloom. Will that help?

Larry in Rio Vista

Hi Larry,

Dear Larry,

If you’re pruning your Wisteria each fall or winter, you may be pruning off the flowering wood. Wisteria only blooms on old wood. It is recommended that only the long, looping tendrils be cut back. Flower buds can be seen as largish, oyster shell or triangular shaped “scales” on the older wood behind these newer growths.

Another reason for a lack of bloom is over-feeding. Your Wisteria can get by without any feeding at all. Really! Your thought about opening the vine up with the chance of providing more sun can be done, but again, you may be removing flowering wood without knowing it, and pruning out the older wood will result in a large flush of new growth in the spring.

Meyer Lemon Tree leaves are chewed up

Dear Garden Guru,

I have a Meyer Lemon Tree that looks like something has been eating the leaves. Can you tell me what this could be and how to treat it?

Shirlee in Tiburon

Hi Shirlee,

I suspect your problem could be citrus leaf miner, especially at this time of year. The moth’s larvae mines through new leaves, causing them to distort and get ragged.  Read our handout about this pest:  Another possibility is young snails.  Applying Sluggo or Sluggo Plus around the base of the tree may help.

Gardening in sandy soil -- help!

Dear Garden Guru,

Help, I am in the outer Sunset and have very sandy soil. Can you give me recommendations on soil amendment and suggestions to plant? Thank you.

Maureen in Outer Sunset

Hi Maureen,

You have the first step right re: getting the soil amended. Indeed, there are little to no nutrients in sandy soil.

Our recommendation is to mix Sloat Planting Mix into the soil, along with E.B. Stone Sure Start when planting — this will allow plant roots to acclimate to the sandy soil, and give them the best chance to spread out and take up any nutrients in the soil.

You will need to “top dress” twice a year in February/March, and again in June/July with Sloat Forest Mulch. This is a great mix that has chicken manure and bark to help hold in moisture and keep nutrients in the soil.

Plant recommendations for your soil: lavender, sage, achillea, erigeron, Ceanothus, all cacti and succulents, escallonia, Festuca and rosemary.

Also see our Mediterranean style plant list- this should offer a good selection of options.

And a link to all our soils –

Getting rid of powdery mildew

Dear Garden Guru,

My neighbor gave me two beautiful rose trees in large pots. The stems/flowers have white powdery mildew on them. How to I get rid of it?

Nancy in Danville

Hi Nancy,

You can treat the powdery mildew with Monterey Bi-Carb. This is an old-fashioned but effective wettable powder (potassium bicarbonate) that kills the mildew on contact. It is safe for use in organic gardens. Another remedy is using Serenade spray. However, to prevent mildew in the future, you can spray roses with Neem or horticultural oil. The powdery mildew spores cannot penetrate the leaf through the oil film.