Ask the Garden Guru

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

Thank you!



Dear Garden Guru,

I just obtained a tall and heavily flowering Cymbidium orchid and would like to stabilize it by transplanting to a deeper and wider pot. Is this advisable, and what sort of growing medium is best?

Tom in San Francisco

Hi Tom,

Yes, those Cymbidiums certainly can be tippy. I would advise you NOT to transplant your orchid until after it finishes blooming in the spring. Wider is much better than deeper, as a deeper pot will hold too much moisture and could possibly rot your plant. For planting, you could use our fine orchid bark OR the orchid planting mix. The orchid planting mix is of course heavier and would act as a better ballast for a tall Cymbidium. We do have an orchid seminar coming up on the evening of February 6th at 5:30. It will be held at our store on Sloat Blvd. Glenn Smith, who will be giving the talk, is a wealth of knowledge on orchid repotting.

Eek, a snake! How do keep them out of my yard?

Dear Garden Guru,

I live on the west slope of Twin Peaks, adjacent to many open spaces. I am morbidly afraid of snakes and I have seen several in the area and one in my yard. I am landscaping the backyard and need to know the best way to keep snakes out of my yard.

Susan in San Francisco

Hi Susan,

I cannot help you with your phobia of snakes, but be assured, the snakes that you have seen are probably not poisonous. I suspect that you have seen garter snakes (black w/ yellow stripes or orangey green) and bull or gopher snakes (ochre yellow and brown to 6′ long). While there may be an occasional Pacific rattlesnake, they tend to live in Manzanita/oak chaparral by creeks. Gopher and bull snakes hunt frogs, lizards, rats, mice and birds.

To keep them from intruding, I would not have a backyard pond or plant material that uses a lot of water. Any area that is irrigated more than 3 times a week will entice little frogs and salamanders. Bird feeders may invite little field mice.

Overgrown shrubberies and ivy will be appealing to rats. You may want to consider putting out some of the new safe rodent baits (they only target rodents, not cats, dogs, birds, etc) to reduce your chances of having rats and mice about. There is also a snake repellant called, fittingly, Snake Away. Sloat does not carry it but it is available online. It is basically napthalate (the main ingredient in moth balls). You may want to consider sprinkling moth crystals or some such along your more “wild” borders.

Keeping plants healthy with beneficial insects

Dear Garden Guru,

I have a fairly shady back yard in the North Beach part of SF. I have put in Heuchera a couple of times. They seem to last/be healthy a year or so and then die. When I go to check the dead looking plant, it comes up in my hand without apparently any roots left. Is something eating the roots? Or possibly rotting them? The plants can look healthy and the next time I go down (a week or so) the leaves have all drooped and it is starting to dry out. Thank you.

Phyllis in San Francisco

Hi Phyllis,

Other than gophers, (you would see the evidence of mounds of earth) roots can be attacked by weevil larvae and cutworms. They are especially prevalent in shaded areas. Other plants that usually fall victim are Azaleas, Impatiens, Primrose, and Iberis. The best plan of action would be to apply beneficial nematodes to the soil. The microscopic nematodes search out, attack, and subsequently vanquish soil borne grubs and larvae. If the roots were rotting, other plants in the area would likely show symptoms of stress as well. These are available via mail order through any of our stores.

Peach borer pest

Dear Garden Guru,

I just noticed that my Donut Peach tree has some clear colored, sticky (sap type) substance on the branches ... what is this and how do I get rid of it safely?

Kathy in Orinda

Hi Kathy,

If the sap you see is on the trunk and lower branches of the tree, I suspect that you may have Peach borer damage. The peach borer looks like a metallic blue wasp and lays its eggs in the bark. The larvae burrow in causing sap (and you may see frass- a sawdust like substance) to leak from the holes.

You can kill the larvae by inserting a thin wire or unbent paperclip into the holes. You may also want to spray the bark of the tree with Bonide Borer Miner Killer (available at any of our stores). If holes are not in evidence, the tree may be showing signs of gummosis disease. This occurs when the tree has received too much water or has poor drainage. This can also occur due to winter cold damage of new growth triggered by a late summer pruning.

Make sure that you feed the tree this spring and again in mid summer to promote vigor. The Miracle Gro Fruit Tree and Citrus spikes are easy to use…or use EB Stone All Purpose Food around the drip line. Be sure to water after feeding. Do not mulch your tree so the soil holds too much water.

Dreading Aphids

Dear Garden Guru,

I have aphids on my anenomes and have treated them with insecticide soap a number of times such that the aphids seem to be gone, but then they come back within a couple of days. I have also tried dousing them with water, but to no avail. Besides controlling them on the plants outside, I would like to bring some cut flowers inside but am afraid of spreading aphids to houseplants.

Susan in Mill Valley

Hi Susan,

I am sorry to hear that you are being plagued. Rather than the insecticidal soap, you may want to consider trying Rose Defense. We have been very satisfied with the results of this product for years. Beneficial ladybugs are also back in the stores. It may be to your advantage to release a box so that they can hunt down the hidden aphids in your garden that are unseen.

As far as cutting flowers to bring inside, a thorough washing with the hose should do the trick. I have a feeling the aphids are hiding under the foliage or on unopened buds. Be sure to spray under the leaves as well.

Get these skunks out of my yard!!

Dear Garden Guru,

Hello! My problem is so many rowdy/noisy and yes, smelly Skunks in my yard. How I can I send them elsewhere without the use of poisons? I refuse to use anything that will kill them or make them violently ill! Just want them out of our yard.They're so noisy they keep me up at night. :-( HELP! I've heard of electronic they work? Thanks for your speedy reply!

K.G. in San Francisco

Hi K.G.,

Since you seem to have a family of skunks regularly visiting the yard at night, I’d almost assume that they live under your house. The first thing I would do is check for openings and check that all crawl ways to gain access under the house are covered. Skunks can readily find that warm spot where there is a gas pilot light. Are your garbage cans secured? Are they digging or eating unpicked fruit?

We carry a product called Critter Ridder that can be applied as a granule or spray. It can be applied to the periphery of your yard and where they are creating a nuisance. Applications will be best in those areas where the animals can walk in to gain access. They are not habitual climbers of fences or trees.

The science behind companion planting

Dear Garden Guru,

I just read your blog from 2008 on companion planting which I found very interesting! It explained why I have so little problems with pests in my combined vegetable/flower and herb garden. How close do these companion plants need to be to each other? I assume the ones which add nutrients to the soil need to be quite close, but what about those that attract beneficials/repel pests? Can they be nearby or in separate raised beds? Within what distance? Thank you very much. This is a wonderful web site.

Susan in American Canyon

Hi Susan,

Companion plants that repel pests/attract beneficials work the best planted close to the target plants. This can be anywhere from 1′ to 6′ away. To provide haven for beneficials, their preferred plants can be planted in another bed or at the perimeter of the garden like hedgerows. Keeping beneficials close by is often sufficient. Plants, when attacked by pests, exude chemicals/hormones that actually attract nearby beneficial insects.

Here is a link to our blog post about companion planting:

Get the varmints out of my yard

Dear Garden Guru,

How do I get the skunks, feral cats and etc. out of my yard? No matter how I fill the big holes under my fence, they dig new ones and come in. The cats also use my yard as a litter box.

Eunice in San Francisco

Hi Eunice,

Sloat will be carrying a new product called Shotgun Repel All later this spring. It is designed to deter those harder to be rid of animals such as skunks and raccoons. In the past we recommended Critter Ridder for the skunks but heard that the product did not help. What did work for skunks was attaching rags soaked in ammonia at their entry points to the yard. It is also important to find any uncovered holes or crawl spaces that go under the house or under stairs.
As far as the cats go, the Bonide Dog and Cat repellent has been effective. Cats also dislike orange oil. Some people save their orange peels, shred them very small and apply to the areas where the cats are defecating.

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.

Getting rid of wild flies

Dear Garden Guru,

Last year I noticed tiny white flies in my garden. They cling to the underside of leaves and become active when I water plants or walk thru the garden. I thought that they would die off during winter rains. Unfortunately, they are still there and are spreading throughout the garden. How do I get rid of these tiny pests?

Tyler in Mill Valley

Hi Tyler,

Whiteflies are hard to get rid of. You may have to do battle on multiple fronts. Whiteflies are attracted to specific plants; Lantana, Hibiscus, Verbena, Tomatoes, Petunias, etc. If you have a severe infestation on a particular plant, you might consider removing it. The larvae are found on the undersides of leaves. To be effective, the undersides of the leaves must be sprayed. Bonide All Seasons Oil or Spinosad will be the most effective. Ladybugs and their young will eat whitefly eggs and larvae. As a last resort, the Bayer All In One or Tree and Shrub Formula are effective systemic insecticides. You can not use these chemicals on food plants. I would ask your neighbors if they also have a whitefly problem. If they do, you should all work together to ensure successful eradication.

Curious if we have your favorite plant or product in stock? Call one of our locations directly and we'll be happy to check.