Each month we select gardening questions and share them with our customers.
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Please note: Our garden guru was on vacation last month so this August we present the best of the Garden Guru answers via our archive. Click the above right categories to view.
GURU tip of the month: July & August
To build healthy soil, dig in a combination of Sloat Planting Mix and Forest Mulch Plus at planting, using 1/3 to 1/3 to 1/3 native soil. Mulch your planting areas and shrub borders with Forest Mulch Plus or compost in spring and summer to not only conserve moisture and keep weeds down, but to add more organic matter. Mulching consistently benefits soil in the long term.
The Garden Guru answers the following questions...
1. Drought tolerant plant list
2. pH content of soil in the Sunset district of SF
3. Using loam Builder as a mulch
4. Keeping buddleia healthy
5. Drought resistant grasses near salt water
6. Healthy gardenia
7. Gardening under a eucalyptus tree = not so much fun
8. Growing haas avocados successfully
9. Lilacs in the Bay Area
10. Planting healthy wisteria
11. Keeping ants off strawberries
12. Growing tea leaves?
Ask the Edible Guru...
QUESTION 1
Q: Dear Garden Guru,
I have a big back yard in the Sunset district of San Francisco which I would like to fill with attractive, low maintenance, drought resistant plants. Any suggestions for specific plants and ideas?
- Stephanie in San Francisco
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A: Dear Stephanie,
I am happy to give you some plant suggestions. I think also that a call to our Design Department would be invaluable to help you out with putting your ideas into a workable plan or consultation to help get you started. The number is 415-388-3754.
Shrubs: Arbutus unedo (Strawberry Bush), Escallonia, Correa, Dodonaea (Hopseed), Euonymus, Hebe, Pittosporum, Westringia, Rosemary, Leptospermum.
Perennials: Agapanthus, Armeria, Artemesia, Convolvulus, Erigeron, Tulbaghia (Society Garlic), Phormium, Centranthus, Aloes and succulents, Lantana
Trees: Metrosideros, Melaleuca, Myoporum. Vines: Bougainvillea, Wisteria, Solanum
QUESTION 2
Q: Dear Garden Guru,
What sort of acid content/PH does Outer Sunset sand-soil have?
Thanks!
Barclay in San Francisco
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A: Dear Barclay,
I'm going to take a guess here that your soil tends to be on the alkaline (higher pH) side. Why? Because it is in a low rainfall area with a low percentage of organic matter. The native species as well as the non natives that flourish in your area, (succulents, Ceanothus, Phormium, salvia, artichoke and Brussels sprouts), are all lime lovers. There is also a lot of alkaline concrete that leaches into the soil. Due to the fact that there are many variables that can account for different soil PH, I recommend that you either use a PH Meter (available at Sloat and pretty accurate) or have your soil tested (Extremely accurate but somewhat costly).
QUESTION 3
Q: Dear Garden Guru,
Can I use the loam builder you sell as a mulch? What would be the best mulch to use for native plants?
Regards,
Sam in San Francisco
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A: Dear Sam,
Loam Builder is Chicken Manure and Mushroom Compost, both of which do not last very long in the soil (great for veggies and flowers, however). It is not best used as a mulch. For the most part, native plants are not particular as to the type of mulch used. If your goal is weed prevention and moisture retention, I would recommend Shredded Cedar or shredded Redwood bark or a new product called Mulch Block. This is made from coconut husks (previously discarded by the coconut industry). It comes in a small compacted bag which will swell to 2 cu ft once saturated with water. It is not only effective as a mulch but environmentally sound.
QUESTION 4
Q: Dear Garden Guru,
What is the safest and most effective way to get rid of the web like worms that are infesting and eating the little budlets of of my buddleia butterfly bush? I am a die hard organic gardener and do not want to hurt the beneficial insects or birds.
- Dawnette in San Francisco
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A: Dear Dawnette,
Buddleia is not only attractive to butterflies and bees for its nectar, but there are a couple of small moths that enjoy the foliage as well. Usually the caterpillars confine themselves to the new foliage tips. The plant is usually vigorous enough to outgrow them. Should you find that the damage is more than acceptable, you can safely use the BT caterpillar killer. BT is a naturally occurring bacteria that will only affect caterpillars. Bees, birds, beneficials and other animals are unaffected.
QUESTION 5
Q: Dear Garden Guru,
We live near the Bay and would like to plant grass in a small area of our yard. What is a drought resistant variety of grass that does well near salt water? Thank you! Beth
-
Beth in Corte Madera,
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A: Dear Beth,
The most readily available by seed or sod is the tall fescue. Medallion is a common trademarked name. The only other grasses that exhibit more salt tolerance are St. Augustine and Bermuda grasses, both of which go dormant in winter. The latter are not available by seed. Should you want a dwarf form (less mowing but slower to "knit") there is the Bonsai Fescue.
QUESTION 6
Q: Dear Garden Guru,
Three years ago I planted a gardenia that was healthy and happy until the deer stripped it of all leaves. The plant is still alive but will not grow any leaves. I have moved it to a sunny, deer free location, but still no luck. Should I throw in the flag?
- Shauna in Pacifica
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A: Dear Shauna,
Just a coincidence here, but I have experienced the same thing. The deer browsed my gardenia as well. Mine was also replanted in a sunny spot. It took 2 years to resprout and only from the trunk and larger branches below the damaged upper stems. The growth rate slowed and the regrowth never amounted to much. I yanked it last week. Too much nothing for too long a time. It may be that the saliva from deer inhibit regrowth in some plant species. In any case, I think it is time for both of us to replant a new Gardenia.
QUESTION 7
Q: Dear Garden Guru,
Live and learn. I moved to Novato about 3 years ago. There was/is a large eucalyptus tree in the back yard. There was nothing growing under it so I said "oh goody, an empty area to fill with my favorite plants"...so I started digging. Three years later, most of my plants have croaked and I now find out that eucalyptus is "allelotopic." Will anything grow under there....groundcover, shrubs, etc.
John in Novato
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A: Dear John,
As a child, I adored Eucalyptus, how the word was spelled, how they smell. As an adult gardener who also inherited a BIG Eucalyptus, I feel your pain. It is not only allelopathy that causes problems but the ultimate competition for nutrients and water. These plants have proven to hold their own under the incredible amount of leaf and bark litter they are barraged with.
Perennials: Acanthus mollis, Dietes vegeta (Fortnight Lily), Phygelius, Chrysanthemum parthenium (Feverfew), Euphorbia, Phormium, Persicaria, Liriope, Eryngium, Centranthus, Clivia, Daylilies, Stipa grass, iris, sedum
Shrubs: Plumbago, Nandina, Euonymus, Carpet Roses, Mahonia, Ligustrum, Correa, Lophomyrtus. (in fact, most Australian natives are good choices), Sambucus, flowering quince
Ground covers: Polygonum, Carex grass, Lamium or Lamiastrum, Euonymus fortuneii
Vines (and maybe they could also act as ground cover); Ipomoea acuminata, Clematis montana, Boston Ivy, Solanum jasminoides and Wisteria.
QUESTION 8
Q: Dear Garden Guru,
I have been given a Haas Avocado tree and am wondering what it needs to grow successfully? I live in the western most side of Novato. My garden gets good sun and other citrus such as lemons and tangerines do very well. Can I expect my new avocado tree to do as well? How big will such a tree grow?
- Tony in Novato
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A: Dear Tony,
The Haas avocado does indeed like the same exposure as your citrus. It is more susceptible to cold and freezing temperatures (plants are hardy to 24-30 degrees). Because of this, you may want to keep your tree in a container that can be protected in winter. The ultimate height of a tree planted in the ground is about 30 to 40 feet. They are also known to cast great shade and shed leaves year round. You will get better fruit production if you plant a different variety along with it such as Fuerte or Mexicola. These last two are also hardier in our northern climate.
QUESTION 9
Q: Dear Garden Guru,
We are from the mid-Atlantic region of the East Coast and loved the lilacs that proliferate there. There seem to be few lilacs growing in Northern Ca. Can they grow here, and what would be the best type to try? Our yard is very sunny and rather windy.
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Olga in Corte Madera
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A: Dear Olga,
We can and do grow lilacs here. They are most readily available in February before they leaf out. The lilacs that do the best are not as fragrant as the French hybrids you are accustomed to. We sell the Descanso hybrids that were developed for mild winter areas. Lavender Lady (lilac), Blue Skies ( medium blue), Big Blue (dark blue), Angel White (uh, white), and Scentsation (red mauve) are the most common. You may not see many in that they are probably confined to the back gardens we don't see.
QUESTION 10
Q: Dear Garden Guru,
I would like to have a wisteria grow across the top of our deck. We live in San Anselmo, so it is dry and hot in the summer, but can freeze in the winter. In order to plant a wisteria in the ground, it would have to be planted approx. 12 feet below and grow up the 12 feet before it can be trained across the rail. If I can plant it in a pot, it would be able to grow along the rail much more quickly. Can you tell me if I can plant a wisteria in a pot and also if it will do well in this area? Nearby neighbors have beautiful, established wisteria, but I am often less successful in getting plants to establish. thank you,
- Joanne in San Anselmo
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A: Dear Joanne,
Wisteria do extremely well here. Freezing winter temperatures are not a problem as they lose their leaves in winter. However, vines greatly dislike containers. You really will be better off if you plant the Wisteria into the ground below. Twelve feet is nothing for this rapid growing vine. You will need to supply a narrow trellis for it to reach the upper rails. Wisteria do best in full sun with well draining soil. Use Planting Mix to prepare your soil as deep and twice as wide as the container. A once a year feeding in late spring with an all purpose fertilizer is sufficient. Water maybe twice a week to establish through the first summer. They are very drought tolerant so 2x a month watering is probably sufficient the following year. Most Wisteria that die are killed by excessive moisture during the winter dormant season. Read more about wisteria on our website here.
QUESTION 11
Q: Dear Garden Guru,
Ants are eating my strawberries just as they begin to ripen. The ants get to them before they're even big enough to pick. Is there I can to stop them?
- Laura in Napa
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A: Dear Laura,
The ants may not be the real problem causers. Often the first damage is done by slugs. The slug makes a feeding hole and moves on. Opportunistic sow bugs and/or ants, attracted to the opened fruit, move in and continue to eat the berry. I suggest you use the Greenlight Slug and Snail Bait. It is formulated with Boric Acid, considered safe and environmentally friendly. Not only will it work on the slugs, but it will control the ants, sow bugs and earwigs as well.
QUESTION 12
Q: Hi Garden Guru,
I am interested in growing my own tea but am not sure if my area is suitable. What growing conditions are necessary for tea plants and, does Sloat stock tea seedlings or seeds?
- Hollie in Castro Valley
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A: Dear Hollie,
Tea, once classified as Thea, is now known as Camellia sinensis. That's right, it is a Camellia! We have only one source for the plants and they are usually in very limited supply. They are available as 1g or 5g plants. We do not have a source for seeds. You can read what the grower has to say about them at www.suncrestnurseries.com. They are native to high rainfall areas and the best flavored come from the higher elevations. You can grow them just as you would a Camellia japonica. Give them acid soil, good drainage, and average water. They require part shade inland but will tolerate full sun on the coast. We would be happy to special order you one.
Here is a link to the locations page of our website.
ASK the Edible Guru...
Q: Dear Garden Guru,
The last few years I have been unable to grow zucchini successfully. The fruit gets to be about 3" long and then the ends of the fruit start rotting. I have tried putting plants in new soil, different areas of my garden, putting them in pots and picking off flowers on the ends of fruit. What am I doing wrong?
- Linda in Greenbrae
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A: Dear Linda,
What you are describing is blossom end rot. It is quite common with squash. The number one cause of blossom end rot is a lack of calcium in the soil. We recommend that all vegetable growing areas/ containers be supplemented with Agricultural Lime at the beginning of each season. The application rates are clearly stated on the package. It is best to fertilize your vegetables with an organic fertilizer such as EB Stone Tomato Vegetable Food. The Nitrogen, Phosphorus, Potassium of 5-10-10. Is good. Too much Nitrogen in the soil can compete with the rate calcium is taken in by the plant. The second cause of blossom end rot is irregular watering. Let's face it, the weather during summer has been wacky. Hot, cold, hot, cold.... Keep your zucchini on a regular watering schedule. Water deeply every second or third day regardless. This will cover you if cold mornings turn to blazing noons and then windy evenings. Avoid overhead watering. The last suggestion would be to mulch your squash with Forest Mulch Plus. This will not only conserve moisture and keep the roots cool, but the top of the mulch will stay drier, allowing the flower to stay drier.
Q: Dear Garden Guru,
I live on Potrero Hill and have new raised beds for a vegetable garden. Herbs, lettuce, tomatoes, cucumbers are all thriving. However, the peppers - sweet and chili - have yellowing leaves and have grown very little. Any suggestions? Thanks?
-
Jacqueline
in San Francisco
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A: Dear Jacqueline,
Glad to hear that everything else is thriving. Peppers are notorious heat lovers, so in S.F. they tend to grow more slowly and are susceptible to over-watering. Let them really dry out between watering (almost to the point of droop) especially as the fruit is ripening, as this makes the fruit much more flavorful. A fertilizing wouldn't hurt as well.
Q: Dear Garden Guru,
I planted San Francisco Fog tomato plants in a container. They have black spots on the leaves. What can I do? I am a VERY beginner gardener. I can submit a photo if you like. Thank you!
- Paula in San Francisco
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A: Dear Paula,
What you describe is late blight of tomato. The fungus forms first on the lower leaves of the plant but can spread upwards, causing most of the foliage to spot. From the leaves, stems are infected, forming brown lesions that disrupt the vascular functions, causing stems to wilt and die. Should the plant defoliate, the tomatoes can burn. This blight is prevalent in cool, wet conditions. We have not had the warmest of springs. Over-watering or watering late in the day before cold nights exacerbates the situation. I suggest that first you remove the worst of the spotted foliage from the top down. Throw this foliage away. Do not compost it. Spray the plant with EB Stone ready to use copper spray at 7 to 10 day intervals about 3 times. Be sure that the tomato is watered before you spray. Avoid getting the foliage wet (other than with the spray). Put your tomato on a regular watering schedule, about 3 days a week.
Q: 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
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A: Dear 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!
Q: Dear Guru,
I'd like to know the best way to grow salad greens throughout the summer.
Can I plant them in succession so that I'll have 4 months of salad? Also,
I live in a foggy pocket of the east bay - does that make a difference?
Thanks,
- Beth in El Cerrito
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A: Dear Beth-
The easiest way to get your summer greens going is to start with pre started cell or jumbo packs. You can always supplement with a sowing of seed.
Should you opt for seeding only, be sure that you do not bury the seeds too
deeply. The best results with lettuces and greens is to prepare the bed (be
sure to mix in Loam Builder and Agricultural lime) so the soil is nice and crumbly. Sprinkle the seeds on top of the soil and then water. The seeds will settle into the soil at the right depth. Carrots and Lettuces need UV light to germinate! You do not need to pull up whole heads, it is better to cut the plants off about an inch above the soil. The greens will quickly regrow. Feed with a liquid fertilizer such as Maxsea All Purpose after cutting. Should you want to pull up whole heads or the plants begin to slow down coming back, you can resow or plant every 3-4 weeks to keep a fresh crop coming. The fact that you live in a cool, foggy location is actually a blessing for growing greens. They do not like it hot. We actually recommend planting in part shade in our hotter areas.
Q: Dear Garden Guru,
Recently I moved from San Bruno to San Carlos. When is the ideal time to plant my
garden seedlings? I wonder if it too early to start my garden (particularly tomatoes)?
Thanks,
Mara in San Carlos
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A: Dear Mara,
You can start your gardening projects right now. This would include planting your
seedling vegetables (peas, greens, strawberries, cabbages, kales, beets, carrots,
onions, spinach), as well as the tomatoes, beans and squashes and basil. All Sloat Garden Centers now have the most varied vegetable selection of the season. As you plant during this cool spring weather, please keep in mind that tomatoes need consistent warmth. If you want to plant tomatoes now, you will need to protect them from cold nights.
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