Dear Garden Guru,

I have had a compost bin for years and regularly put kitchen scraps, yard waste, etc. into it. However, it seems this bin has turned into a worm farm. The whole bin is full of worms! I know their castings are great fertilizer, but when I put any of this on my plants, they die. I think it's too strong. Can you suggest how I might be able to use the contents of my bin on my plants without killing them? Thanks!

B.E. in San Francisco

Hi B.E.,

I would use the compost that is below the working worms. The compost here is less hot and has also had the benefit of further decomposition by soil fungi and microbes. You may want to add more “brown”/carbon to the bin. Excessive green/nitrogen tends to be hotter. It may help to water the plants you apply the compost to first and then water again after application. You can also make compost tea. Fill a 5g bucket 1/2 full of the worm compost. Add water and stir. Strain the mixture in an old pillow case or decant. Use immediately. A better tea can be created if you can aerate it. This can easily be done with an aquarium pump and some plastic tubing. Allow the concoction to Bubble for 2 or 3 days and stir morning and night. Some people add 1/4 cup of molasses to feed the beneficial bacteria and fungi in the solution. After straining or decanting, use immediately.

Dear Garden Guru,

I am a first time gardener and live about 1 block away from the beach in the outer Richmond. I am going to start a few plants in 6 wine barrels and am wondering what the best plants are for a first timer, near the beach using barrels. I would love to do some greens (swiss chard, kale, lettuce), herbs and squash. Any suggestions?

Lauren in San Francisco

Hi Lauren,

You can be quite successful growing vegetables and flowers in barrels, even so close to the beach. The greens you mention will be fine as they can be grown nearly year round. You should also consider starting your cole vegetables, broccoli, Brussels’s sprouts and cabbage. Peas and green onions will also like your weather and are easily started from seed. It is too late to plant squash now. For herbs, plant parsley, oregano, catnip, and rosemary. Sage, thyme and basil want it warmer and can be finicky.

Annual flowers that can be planted with your vegetables are Alyssum, Lobelia, Cosmos, marigolds and summer snapdragons. You want to keep the finished flowers picked off to keep the plants happily blooming. This is what we call “deadheading”.

Lantana, succulents, Armeria (Thrift), Euphorbia, Coreopsis, Erigeron, Agapanthus, Dianthus and Argyranthemum (Marguerite daisy) are easy, colorful perennials for the coast.

Dear Garden Guru,

I have a long east-west lot 1 block from the beach in the Sunset. I would love a big garden of veggies and drought-tolerant natives, but unfortunately most of my lot is concrete! I think I can break most of it up by sledgehammer, but I have no idea what to do after that. Suggestions?

Laura in San Francisco

Hi Laura,

If you are willing to remove the concrete, it may be best to create your garden in raised beds that are protected on the bottom with hardware cloth/chicken wire. The gophers in the Sunset are out of control and would no doubt wreak havoc on a fresh new garden. I would have you contact our Design Department at 415-388-3754. They can assist you with site design and native plant choices.

Dear Garden Guru,

I have been planting a lot in pots. Twice recently when I transplanted to bigger pots because plants weren't doing well, I discovered that the soil in the bottom half of the pot was a shade lighter than the top. Why? I always reuse soil. Can I replant in this lighter soil, put it into my own garden composted (not very hot) or into the city compost?

Luby in San Francisco

Hi Luby,

The lighter soil at the bottom of the pot is due to a decrease in organic matter, soluble salt buildup (fertilizers), calcium carbonate (hard water and reduced drainage). There is nothing unsafe about it so it can be added to compost piles both at home and in the city yard. If you want to reuse the soil, I recommend mixing it first with fresh soil to disperse the minerals and improve the nutritional content.

Dear Garden Guru,

We have a number of citrus trees; lemon, lime and orange. I liked to compost as much as possible, but I've read that citrus rinds shouldn't be added to worm boxes or standard compost bins. Is there another way to compost that works for citrus rinds? Also, which plants would benefits from citrus compost?

Anne in Greenbrae

Hi Anne,

It is true that Citrus should not be added to worm bins regularly because they create too acidic an environment for the worms. Even then, an occasional peel would not break the farm. There is nothing wrong with adding Citrus to regular compost as long as you provide enough carbon (brown) to balance the nitrogen (green) of the oranges. The resulting compost will be on the acid side so would be ideal for alkaline soils, and for use around acid plants such as Azalea, Rhododendron, fern, Hydrangea, Gardenia and Camellias. You might consider starting a separate pile so that you are “manufacturing” 2 separate mixes.

Dear Garden Guru,

Can mesquite charcoal be added to garden soil. We have several buckets full. Our soil is clay under oak trees. The charcoal is tiny pieces. Thank you for your help.

Mary in Diablo

Hi Mary,

You can add the charcoal to garden soil but disperse it sparingly, and if possible, try to crush it into more of a dust like formulation. Too much charcoal inhibits nutrient availability.

Dear Garden Guru,

What are some good predatory insects to have in the garden and how do I get them to stay there?

Dave in Oakland

Hi Dave,

Probably the best commercially available beneficial insect is the lady bug. If your garden is plagued with a good infestation of aphids and whitefly, the beetles will stay and lay eggs. The real eaters of the pests are baby beetles which resemble little black alligators. The adult beetles feed mostly on pollen and nectars so it is important to have a reliable food source to keep them around. Choose plants such as Achillea, flowering dill and fennel, most of the daisy type plants.

Good bugs to encourage are lacewings, soldier beetles, small parasitic wasps, and hover flies. Planting plenty of white alyssum along with daisy type plants such as feverfew, marguerite daisy, and zinnia will attract the adults. Wasps are attracted to hormones released by the pest attacked plants. These hormones can be mimicked with catnip and Nepeta mint. I suggest you invest in one of the handy, inexpensive ($5.99) Mac’s Field Guides for Beneficial and Bad bugs. It is a good starting place to begin learning about bugs.

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.

Dear Garden Guru,

I have spread some redwood mulch over my rose beds. Should I mulch my potted roses and plants as well? What are the "rules" for mulching pots?

Judy in San Bruno

Hi Judy,

Mulch away! The benefits will be fewer weeds and less water consumption. The only down side is that if there is not enough room to hold water, the mulch may run out of the pot. If that is a problem, you can use green moss (sold in bags) like you would use for a hanging basket or indoor plant.