Each month we select gardening questions and share them with our customers.
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The Garden Guru answers the following questions for May
1. Amending soil with coffee grounds
2. Healthy Camellias
3. Getting ahead of whiteflies
4. Keeping your Daphne Odora alive
5. Transforming dirt to healthy soil
6. Best fruit tree varieties
7. Preventing mold spores on dahlia leaves
8. Rust on rose leaves
9. Organic slug control
10. Testing soil for lead
11. Keeping potted plants happy
12. Another frustrated gardener tries to deal with gophers
Ask the Edible Guru...
QUESTION 1
Q: Dear Garden Guru,
I have heard that coffee grounds are "healthy" for outdoor plants, but I never learned the specifics about how to use them. Can you help me?
- Veronica in San Rafael
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A: Dear Veronica,
Yes, coffee grounds are rich in plant nutrients and break down rapidly. Some people will add them to their compost while others use them as a mulch around their plants. Even just sprinkling them onto flower or vegetable beds will help improve the soil. Container plants like them too, just apply directly to the soil surface. You want to ensure that you don't pile the grounds on too thick, though. Up to 1" should suffice and it wouldn't be a bad idea to skip applications every once and a while to allow all stored nutrients to leach into the soil.
QUESTION 2
Q: Dear Garden Guru,
I have a camellia (pink...name unknown) growing next to my front door in a plot surrounded by boxwood. It gets only morning and early mid-day sun. Many of the buds brown and collapse before opening and of the flowers that do open, most turn brown and die quickly. Any tips that will help me have a healthy camellia bush.
Thanks!
John in Novato
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A: Dear John,
Your Camellia sounds like it is battling Botrytis or Petal Blight. Both diseases persist where there is a history of the diseases, when there is high humidity and temperatures are between 45 and 70 at blossoming time, and where there is poor air circulation.
Your first defense is in adequate sanitation. Remove all browned, dry blossoms
from the shrub, remove all fallen petals and flowers. Once the plant and area are
cleared of blossom debris, spray the soil and plant with Copper Spray or Serenade.
Mulch the Camellia with 1 1/2 to 2 inches of bark mulch such as Micro Bark. The
reason for this is that the spores can last up to 4 years in the soil. You are
covering them so they don't splash back up onto the plant. This cleanup should be
done right after the plant has finished blossoming. Spray the Camellia again in
the fall and again when the buds have grown large before flowering. That should
break the cycle. Spraying your camellia should be on your gardening calendar each
fall.
QUESTION 3
Q: Dear Garden Guru,
Every year I fight whiteflies in my garden. Last year they got so bad that I was reluctant to eat the tomatoes and cucumbers toward the end of the season for fear that they may be carrying lots of larva in the fruit. I have used sprays for whiteflies but I can't seem to get ahead of this pest. Perhaps I am not using enough spray but I don't like putting too many chemicals on my garden. What do you recommend?
Regards,
Diane in Novato
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A: Dear Diane,
Whiteflies really are obnoxious and more difficult to control too. I have a number of suggestions for you.
1. Put up sticky yellow traps or plant Nicotiana (a trap plant) to monitor the population. If you see great numbers, chances are they have over-wintered in your yard or nearby. Check Lantana, Verbena, Hibiscus, Melianthus, Coleus or Solanum for signs.
2. Release Ladybugs. Baby ladybugs can devour thousands of whitefly eggs and nymphs in their lifetime. A juvenile ladybug looks like a small black "alligator".
3. Tomatoes, peppers, eggplants and other vegetables are very attractive to whitefly. Spray the foliage with Seaweed Extract (according to directions). Not only do the plants benefit from the micronutrients, the seaweed spray seems to make the foliage undesirable for egg laying! This can be done as soon as plants are set out.
4. Whiteflies often attack plants that are deficient in Phosphorus or Magnesium. Feed plants with SUL PO MAG or Epsom salts to increase immunity.
5. If you really have a bad outbreak this season, I would have you obtain "The Whitefly Destroyer" or Green Lace Wings. These are actually a mail order for beneficial insects. Any Sloat Garden Center can sell you the mail-in offer. You send it, and the bugs are shipped direct to you. Check with your neighbors to see if they also have whiteflies. Maybe all of you can do a beneficial bug release (including Ladybugs).
6. Spraying is difficult as most of the problem is under the leaves. Bonide All Seasons Oil or Spinosad will kill nymphs and adults. Both are non toxic (to us and pets and birds) and are safe to use on vegetables. You should spray every 7 to 10 days to get all hatching eggs.
QUESTION 4
Q: Dear Garden Guru,
I absolutely love Daphne Odora and its delicate fragrant flowers. I was told they require good drainage and morning sunshine. But my plants only seem to last a year or two and then die off. What can I do to keep my beauties going longer?
- Grace in San Francisco
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A: Dear Grace,
Sigh. Daphne plants do just up and die sometimes. Probably the best way to keep them going is to plant them in containers. In a pot you can control the drainage, exposure and food supply. A shallow as opposed to deep pot is best. Use a fast draining potting soil such as Sloat Bay Area Blend. Feed monthly with a liquid fertilizer such as Maxsea Acid Formula through July. Daphne prefer morning sun until 2:00 and then a bit of afternoon shading if you live in a hotter inland area. On the coast they enjoy full sun. Though shadier aspects keep Daphne's roots cool, the soils here tend to stay moister and Daphne does like to dry out a tad between watering. If you really must have your Daphne in the ground, amend the soil with micro bark 50/50 (yes, bark) this will ensure fast drainage and provide an acid environment. Apply a slow release fertilizer such as Osmocote in early spring then supplement with the Maxsea once a month through July.
QUESTION 5
Q: Dear Garden Guru,
What do I use to transform my dirt to growing soil?
-
Jane in San Francisco
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A: Dear Jane,
If you are interested in beds for vegetables, annuals and perennials, we recommend digging in Loam Builder. One bag covers 25sq feet. For luxury soil, incorporate additional Planting Mix at the same rate. Use 1 5 lb. box of Agricultural Lime and 1 box of 4 lb. Sure Start for every 100 sq feet.
If the areas are for shrubs, trees, and woody perennials, we recommend either Forest Mulch Plus or Planting Mix. Luxury soil would incorporate them both. Follow the same rates as for vegetable beds. You will not need the lime, but Sure Start or organic All Purpose fertilizer is a helpful addition.
QUESTION 6
Q: Dear Garden Guru,
I'd like to plant a couple of fruit trees in my south-facing back garden - probably apple and/or pear. We live near City College, have good soil, and the lemon tree is thriving. What variety of fruit trees would do best?
- Keren in San Francisco
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A: Dear Keren-
Apples, pears, and plums are the preferred flowering fruit trees for your location. Apricots, though more temperamental, will also work. We recommend these varieties of apple: Golden Delicious, Fuji, and Gala. For pear, choose the Asian pear 20th Century, Bartlett, or Comice. Goldkist or Blenheim apricots are best and the Santa Rosa plum is almost problem free.
QUESTION 7
Q: Dear Garden Guru,
I'm planning to grow dahlias again this year in Sausalito, and wanted to see if there are solutions, specifically organic solutions, to preventing mold spores on the leaves.
Christine in Sausalito
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A: Dear Christine,
There most certainly is a spray for the mold. It is called Serenade and comes either as a concentrate or ready to use spray. It is organic and listed by OMRI (Organic Materials Review Institute). Believe it or not, the "active" ingredient is a natural bacterium that feeds on fungus! This bacterium does not affect living plants or other wildlife. Greenlight Rose Defense, containing Neem oil can also be used. If sprayed before there is a problem, it will protect plants from Powdery Mildew. Both are available at all of our locations.
QUESTION 8
Q: Dear Garden Guru,
I am in need of your wisdom. Some of the leaves on my "Smooth" (thornless) rose bush are turning yellow with orange spots on the underside of the leaves. I'm not sure what is happening...any advice? It is just starting to bloom right now and I would hate to throw it away.
- Daniel in San Francisco
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A: Dear Daniel,
You are describing a fungus disease called rust. The yellow spots show where the fungus is invading and the orange spots are their spores, ready to spread to other leaves. You don't need to throw the plant away. I would remove the leaves that are the most affected from the bottom up. You can safely spray with Serenade Disease Control (a safe and effective spray). Spray once or twice at 7 day intervals and that should do the trick!
QUESTION 9
Q: Dear Garden Guru,
Like everyone else on the coast, we have snails and slugs! We also have cats who wander the yard.... how do we know if a particular plant is susceptible to snails/slugs, and how to we control them in a way that won't harm our kitties?
-
Kirsten in El Granada
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A: Dear Kirsten,
Many plants are susceptible to slugs and snails. Plants with leaves that don't have a hard or waxy surface are eaten the most. Think about Hosta, Marigold and Broccoli leaves for the texture they seem to prefer. As far as hiding places, snails and slugs love plants with strap like foliage such as Agapanthus and Fortnight Lily. They hide in shaded ground covers like ivy. Good news for all of us is that there is now a non-toxic slug and snail killer. It is called Sluggo and will not harm people, pets, birds, worms or fish! It is made of iron phosphate, a naturally occurring soil mineral. Once eaten, the slugs and snails stop eating. Some kind of mollusk thing.
QUESTION 10
Q: Dear Garden Guru,
I live close to the highway in an old house. I've heard I should test my soil for lead before planting anything edible like vegetables and herbs. Is this true and what is the best testing method? There seems to be a lot of different options out there!
- Robin in San Francisco
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A: Dear Robin,
You are right, this is becoming quite an issue. Not many of us thought about possible lead contamination in our homes or soil until 5 or 10 years ago. Though toxic, it is of main concern for small children and their developing neurology. There is a testing facility called Anresco, Inc. at 1370 Van Dyke Ave. 1-800-359-0920. They will test soils for $40.00 a sample. As far as recommendations to have it removed, well therein lies the real problem. Yes, plants will take up heavy metals. Is it dangerous to ingest them? There really hasn't been that much research on home grown produce in urban settings. We don't really know how much lead is out there or how much we ingest from traditionally grown crops and fields. It is a fact that some plants are better able to take up lead from the soil and they are starting to be used to "clean" soil for edible crops. Consider growing Sunflowers, chard and kale for a couple or three seasons in your planting beds. They can then be disposed of after they die. Consider growing your edibles in containers with fresh soil every year if exhaust from the streets is an issue.
QUESTION 11
Q: Dear Garden Guru,
I live in the Mission and I get a fair bit of sun in my garden as well as shade. I just planted Ranunculous, Gerber Daisy and Heliotrope in pots and boxes and they all either died or withered within days. What's the best way to keep potted plants like these happy? Thanks!
- Uda in El Granada
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A: Dear Uda,
Oh dear. I suspect that the plants declined due to too much water and /or being planted too deeply. Planting should be done so that the soil level in the container is the same as the small pot you bought them in. Planting them about 1/4 to 1/2 inch higher is even better so that they settle in just right after watering. As the weather has been cool, watering two to three times a week will have been sufficient. The next time you purchase plants, a Sloat member can help steer you to appropriate selections.
QUESTION 12
Q: Hi Garden Guru,
I have an issue with gophers! They have eaten over $20 worth of my lambs ear, and other little plants that I have recently planted in my new garden. I am attempting to put coffee grinds as a ground layer between the gophers and my plant, but I don't know yet if this is going to work. I have researched ways in which to deter the little guys, but I keep getting information on how to KILL them and I don't want to do that. Do you have any suggestions?? I know that castor bean, garlic and gopher purge are recommended, but they are poisonous to them and I don't want to kill them. I hope to hear from you sooner than it takes for the gopher to finish his all you can eat buffet! :)
- Amy in San Francisco
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A: Dear Amy,
The castor oil products will not make the animals sick or kill them . They really are just repellents. Bonide Mole and Gopher is a liquid form (attaches to the hose) and Gopher/Mole Med is granular. There is also the Sonic Mole and Gopher Chaser. You can purchase online a product called Shake Away, which is Fox urine in a granulated formula. Human hair and dog feces have also been known to work.
ASK the Edible Guru...
Q: Dear Garden Guru,
I recently started a small, potted herb garden on my condo balcony: rosemary, thyme, spearmint and sage. I love having fresh herbs when I cook! A friend told me that many herbs thrive despite a bit of neglect and that, as I'm new to gardening, to make sure I don't become overenthusiastic and water my herbs to death. How can I gauge when to water my plants?
- Jean in San Francisco
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A: Dear Jean,
First, make sure you've planted your herbs in pots large enough to hold extra moisture and allow for growth. Terra cotta pots will dry out faster than glazed or plastic pots, especially on a balcony that is exposed to wind. Those 3" or 4" herbs are best started in a minimum 6" pot. Even better, use 10" to 12" pots with 3 or 4 plants. You will not need to water everyday. 3 to 4 times a week when warm and breezy is the rule. If plants have lost their "gloss" and look dull, it is time to water. If they look wilted in the morning, time to water. Make sure enough water is added to the pots so that water drains from the bottom. This ensures that all the soil has been moistened.
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,
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.
