SF Flower & Garden Show seminar: Master Tomato Growing in Containers by tomato guru Cynthia Sandberg

                                                                                                             Photo: S.Smith
Cynthia Sandberg (in plaid) helping a gardener with his tomato selection at the Love
Apple Farm tomato booth  at the San Francisco Flower & Garden Show on March 24.

"Hello fellow tomato freaks," Cynthia Sandberg  of Love Apple Farm called out to the assembled crowd at her "Master Tomato Growing in Containers" seminar.  Judging by the number of attendees at last week's San Francisco Flower & Garden Show seminar, many folks want to become masters.

Whether you grow tomatoes in containers because you don't have a yard, don't have the right combination of sun and space, are bothered by gophers or just want to try container gardening, Sandberg was ready to share her  secrets in the scheduled 45 minutes.

While she's grown tomatoes successfully  in the ground for 20 years (after all, Love Apple Farm is the exclusive kitchen garden for Los Gatos' Manresa restaurant), she admitted that container growing is much more demanding.  It took four years of trial and error before she hit upon the winning combination of ingredients and processes for maximum yield and flavor.

Sandberg began with a caveat.  "Don't go rogue on me, don't pull a Sarah Palin", she joked, which elicited laughter.  "I want you to skip four years of work but you've got to follow my directions," she explained.  After the seminar she cheerfully urged everyone to "go forward and be fruitful."

How to Grow the Best Tomatoes in Containers

• Start with at least a 15-gallon container (an inexpensive black plastic one will do) that is 17" tall and 17" wide.  If it's been used before, wipe it down with a solution of one part bleach to 10 parts water).  Do not plant more than one tomato in it.  "If you invite me over for dinner, I better not see four plants in it," she said.
   
• Her preferred potting soil is Sun Land brand. Her tip: you can find Sun Land at Orchard Supply Hardware under the OSH label; one cubic foot bag is $5.  It's OSH potting soil, not premium potting mix.
   
• Put four inches of potting soil in container and then add 1-2 handfuls each of fish and bonemeal in the bottom.  For in-ground tomatoes she uses a fish head but this may be too fragrant for a container. 
   
• Add two handfuls of Sustane which is a timed release dry fertilizer that UC-Santa Cruz also uses. She uses it on everything.
   
• Add a handful of worm castings
   
• Add one tablespoon of humic acid, aka Humate Soil Conditioner (microbial agent which increases tilth in soil)
   
• Add 3-4 crushed chicken egg shells.  Tomatoes need a lot of calcium as they are prone to deficiencies which is why you add bonemeal, fishmeal and eggshells.
   
• Add 2 uncrushed aspirin tablets - she explained the salicylic acid jumpstarts the tomato's auto immune response systems.
   
• Pop out the plant from its original container and cut off the lower leaves- 2/3 of the stem should be under the soil level. It will root all along the area under the soil which make the plant sturdier and healthier.
   
• Sprinkle 1/4 teaspoon of mycorrhizae (Root Zone is one brand) on the rootball.  This helps it to resist the dreaded wilts: fusarium and verticillium. Sandberg is all about disease prevention.  "Once the plant is diseased it's almost impossible to save."
   
• Then water it well.  The first day it will need lots of water.  Water it well and then do it again and again.
   
• And how does she support her container-grown tomato that she says can grow 8 feet tall or higher?  Tomato cages made from concrete reinforcing wire - from the 7-foot rolls. 
   
• Sandberg says the tomato plant will grow happily through May and June but offers two tips as the season progresses:

(1) In mid-June the plant  starts to degrade and needs supplemental fertilizer. Her formula: One handful of worm casting in a one-gallon bucket of water, strain into a two-gallon container, add 1.5 crushed aspirin tablets and spray the foliage once a week through its entire life.  She also advises drenching the rootball with worm casting tea once a week.

(2) The black plastic containers can supercook the plant.  She will pin a shadecloth  to shade the pot from sun on the south side  - she shades the pot, not the plant. Starting in August the containers might need watering every day.

Summary of Items Needed:

• 15-gallon container
• Good quality organic potting soil
• Bonemeal
• Fishmeal
• Sustane
• Worm castings
• Aspirin tablets
• Humic acid
• Egg shells
• Mycorrhizae fungi

While you can find the container, soil, fish and bone meal, aspirin and egg shells readily in the Bay Area,  finding Sustane, humic acid,  mycorrhizae fungi and pure worm castings are a little more challenging.  Some of the nurseries carry soil optimizers and soil which contain the ingredients but not the actual items. Cynthia Sandberg mentioned that Mountain Feed and Farm Supply in Ben Lomond carries all of them.  I checked and they do, in manageable quantities except that Sustane only comes in a 50-lb bag ($38).

Since the Love Apple Farm annual tomato plant sale is in full swing, make a trip over the hill and pick up some plants and worm castings, then it's a short drive to the store for the remainining items.  When you are eating fresh organic luscious tomatoes this summer you'll be glad you followed her plan.

  For more info:  For more info and detailed explanations on Love Apple Farm  tomato growing; see a home gardener's tomato growing success story;  leave a comment on her blog and a person will be chosen at random to win 5 tomato plants;  follow her on Twitter.