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Greetings!
Last week I mentioned that the perfect soil for gardening was either loam or sandy loam. Container gardening modifies that a bit, but it is interesting to me that no customer has ever questioned why the soil they purchase for pots doesn't at all resemble the soil in the ground. But then, I didn't question it either. For the first 15 years of my professional life I thought the people who made potting soils knew what they were doing.
Potting soils and container growing became very popular after commercial brands of potting soils were first heavily marketed in the 1980's, but soon found that a number of plants rarely succeeded. We became very hesistant sell Boston ferns, Camellias, Cyclamen, Dracaena palms, Gardenias, Ming aralias and even Citrus and Avocado for growing in containers. The industry eventually came up with many rules to keep potted plants alive.
"To avoid overwatering, don't put a small plant into a large pot"
"Do not water until the soil is dry an inch or two deep"
"Do not bury the trunk or stem with soil more than a fraction of an inch deeper"
"Mix with perlite or sand to improve drainage"
"Place a layer of small rocks at the bottom to improve drainage"
"Drill more holes in the pot for better drainage"
"Use clay pots because they breathe better"
You probably heard other rules also. In fact, they all work to some extent because potting soils, with few exceptions, are basically composts. Compost consumes oxygen and suffocates the plants roots. Compost will create toxic conditions for roots if present in large amounts. Compost is less toxic if well aerated and arranged in a thinner layer. All of the above rules do one or the other.
In 1995 a scientist convinced me that organic compost is not ideal as a growing medium in containers or otherwise. In side by side comparisons I found that sand as a potting soil produced far better results (vigor, foliage size and foliage color) than the commercial potting soils that we were selling. It's as if the commercial potting soils were actually poisonous.
Again, last week I mentioned that the perfect soil for gardening was either loam or sandy loam. Container gardening modifies that a bit.
Think of soil in the ground is like an endless sponge. Get the top real wet (saturated) and the excess water gradually moves because of gravity to drier areas below and is replaced by air. When this happens we say that the soil has good drainage.
Soil in a pot is like holding a large sponge vertically. Get the top soaking wet and the water travels to the bottom and starts to drip off. However, about a 2-inch layer at the bottom remains saturated and won't drip. This is the perched water table of the sponge. The sponge's porosity holds onto a certain height of water stronger than gravity. If you place the sponge on top of a non-porous material the perched water remains in the sponge. The water won't leave unless the porosity of the material below is equal or greater.
The same thing happens with soil in a container made of non-porous material. Natural soil usually has a higher perched water table than a sponge. Higher porosity results in a higher perched water table. If water sits around roots too long (without movement) the oxygen will become depleted and the roots suffocate. If the soil contains substantial clay the thickness of the perched water table can be higher than the container and few plants would survive.
So, if using natural soil for pots, either the pot has to be very tall (significantly taller than the perched water table so roots have a place to breathe) or the soil has to be very coarse (low porosity to lower the perched water table).
LET'S STEP WAY BACK IN TIME
People have been growing plants in containers in China and Japan for thousands of years. In the art of Bonsai it is well known that sand creates vigorous growth and the addition of clay causes slower growth and smaller foliage. In John Naka's Bonsai Techniques, the bible of Bonsai for the Western Hemisphere, I don't recall seeing any organic matter used as a growing medium. The soil mixes started with sand and added some loam (containing sand, silt and clay) to lower the permeability. To create miniature trees you don't want the excessive vigor that pure sand produces.
The Orangeries in Europe (mid 1500's to 1900) were the first greenhouses built to protect potted Citrus trees. Some surviving literature shows that the trees were planted in soil that was 97% sand.
Literature from the Royal Horticultural Society in the early 1900's proclaimed that loam soils were ideal for growing plants in containers.
When I was a kid (around 1960), my brothers and I used my father's pile of sandy loam as a giant sandbox. My father grew more than 90% of his inventory in soil that was mostly sand. In those days most growers did the same.
A few years later, however, our sandbox changed forever. Nurseries began incorporating redwood sawdust and/or peat moss to lighten the containers. This actually worked fairly well as a growing medium because both redwood and peat decompose at a slow rate. Not so good for making forts and roads.
When the price of redwood skyrocketed in the 1980's everything changed. Sandy loam mixed with fir shavings and fir bark fines (ground bark) became the normal growing soil. Commercial potting soils that were primarily fir bark fines became popular. We began noticing that container soils settled severely after a year (because fir decomposed rather quickly) and root rot and overwatering became major problems. An agricultural extension agent told my father to stop watering plants everyday to avoid root rot problems. Up until 1985 my father had watered all his plants daily during warm weather with no problems. Apparently no one was making the connection between root rot problems and the newer soil mixes.
In the 1980's compost was promoted as the cure for all soil problems. The more you add (we were told), the better your soil. However, in the early 1980's Jack Wick, the founder of the California Nurseryman's Association, handed me a paper that outlined research done by undergraduate Carl Whitcomb, who came to the conclusion that the ideal amount of compost to incorporate into the ground when planting landscape plants was zero! Apparently not enough people believed in Whitcomb's conclusions even though he earned his doctorate and became a World famous authority on woody plants.
In the early 1990's I was totally confused on how to grow plants. The things we were told to do weren't working. We had to use all our skills, time and effort just to avoid overwatering plants!
In 1995, after growing impressive plants in pure sand I decided to take a chance and stop following the industry. I didn't want to grow plants in pure sand or sandy loam (as my father had) due to weight. 30 to 40 pounds for a 5-gallon plant is rather excessive! I started with sandy loam and added pumice rock and peat moss to lower the weight. Pumice is a natural rock that is 70% air pathways, the absolute best way to increase permeability. Peat moss is the best material to store water and very slow to decompose. (Clay holds more water, but won't release as much to the plants.) That first soil mix I created was very slow to drain (the water sat on top for hours), however, the rose plants we grew in it looked fabulous with foliage significantly greener than plants from other growers. I substituted sand or decomposed granite for the sandy loam and suddenly growing just about any plant became very easy! We could once again water freely without causing root rot.
THIS IS TURNING OUT TO BE LIKE RECALLING THE HISTORY OF THE WORLD! I'LL FINISH THIS SUBJECT NEXT WEEK.
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GARDEN NOTES
This late rain is coinciding with blooms on many apple and pear trees. This may cause a lot of fireblight, especially on Gala apple trees and the Callery pear trees that line our parkways. Watch the foliage near the flowers. Any blackening should be pinched off quickly to stop infection. An application or two of Monterey AGRI-FOS will help.
We are not only selling a lot of tomato plants, we are currently stocking a lot of basil. Basil can be grown outdoors without any protection once night temperatures stay above 50 degrees F. We are just about there. You can plant now and place a box or bucket on top on cool nights. Overcast weather keeps our night temperatures in the mid-50's. Clear nights are just below 50.
We are currently growing about 500 fruit trees and perhaps 200 grape vines. Many will be available within a month and most before summer. In the meantime, we have some interesting ornamental plants to offer.
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AVAILABLE THIS WEEK
All prices include tax if applicable
Athyrium niponicum 'Pictum' JAPANESE PAINTED FERN 1-gallon $12
This fern cultivar has been in my garden for over 10 years. It grows about 1' tall and 2' wide and lights up the shady walk to my front door. The foliage is light green with silver and burgundy accents. BEAUTIFUL! The leaves are deciduous and turn brown for the winter (bare for 2 months +). My specimens do well in pure LHN ACID MIX.
Calylophus hartwegii 'Texas Gold' SUNDROPS 1-gallon $8 This Texas native perennial loves heat and is tolerant of drought when established. It grows about 1 foot tall and spreads to 2 feet or more wide. It blooms yellow fading to orange in spring and again late summer-fall. Related to evening primrose (Oenothera), but not invasive. Situate in full sun to light shade.
Fuchsia thymifolia 1-gallon $9
back in stock
Loropetalum ch. 'Zhuzhou fuchsia' CHINESE FRINGE TREE 1-gallon $12
back in stock Michelia figo BANANA SHRUB 1-gallon $12 Small, but blooming.
Phormium 'Dark Delight' NEW ZEALAND FLAX 5-gallon $40 This is a nice cultivar of the dark-leafed Flax plants. The reddish-purple foliage glows during the cool season. At about 5 foot tall it is shorter than average, but has broader leaves than most compact varieties. A nice accent in sun or part sun.
Phormium 'Guardsman' NEW ZEALAND FLAX 5-gallon $40
Phormium 'Rainbow Chief' NEW ZEALAND FLAX 5-gallon $35 This flax (formerly known as Maori Chief) is perhaps the best of this color combination. It is shorter (at about 5 feet tall) and more stable (less likely to revert to solid green or bronze) than similar cultivars. Most striking appearance during cool weather and in part shade.
Rose 'Gruss an Aachen' 1-gallon $10 I wasn't going to sell roses due to difficulty of transporting, but when my favorite grower offered this variety in small containers, I couldn't resist. This German cultivar was introduced in 1909 and is considered to be the first floribunda as well as the first English-style rose. David Austin says that this was the prototype for his English Roses. Fragrant, large flowers with lots of petals, on a 3-4' bush that repeats all year. I have 3 bushes in my front yard under a small tree. The color is creamy amber in cool weather, creamy pink in warm weather. The foliage can get a bit of mildew, blackspot and rust but rarely bad enough to require treatment. A former employee who is in charge of a large estate in Bel Air says that this rose blooms better than Iceberg in their garden. An outstanding choice.
Salvia 'Orchid Glow' HYBRID AUTUMN SAGE 1-gallon $9 This new hybrid is between Salvia greggii and Salvia microphylla. The result is a brillian purple magenta flower on a compact bush. Expect upright growth to about 18 inches tall and wide with color much of the year. Flowers are larger than typical for either species. VERY SHOWY.
Westringia fruticosa 'Smokey' COAST ROSEMARY 1-gallon $9 This is an excellent foundation shrub usually maintained as a tall mound and often seen as a hedge. Full height is about 5 feet high and wide, but is often kept at 3 foot. The variegated leaves give the plant a silver gray appearance. White flowers appear all year but are heaviest in spring. Easy and drought tolerant when established. Loves coastal conditions.
Wisteria Cooke's Special Purple 5-gallon $40 Wisteria vines aren't perfect. They need constant pruning to keep them in check and a very strong support, but what a show. Cooke's Special Purple Wisteria is the deepest purple we've seen and starts the growing season with a month-long spectacle of foot long, fragrant racemes. This is one of the best, repeating cultivars we've seen and will bloom lightly throughout the growing season. Situate in full to part sun. Every home I've lived in has been graced by the beauty of this vine. At my current home it is staked and trained as a weeping tree.
ALSO
Carex oshimensis 'Evergold' GOLDEN SEDGE GRASS 1-gallon $9
Convolvulus mauritanicus GROUND MORNING GLORY 1-gallon $9
Hebe pimeleoides 'Quicksilver' 1-gallon $9
Ophiopogon planiscapus 'Nigrescens' BLACK MONDO GRASS 1-gallon $11
AND MUCH MORE!
EDIBLES
Tomatoes quarts $3 HYBRIDS Better Boy, Big Beef, Champion, Early Girl, Lemon Boy, Momotaro
HEIRLOOMS Aunt Ruby's German Green, Black from Tula, Black Krim, Brandywine Yellow, Cherokee Purple, Coustralee, Green Zebra, Kellogg's Breakfast, Old Time Tasty, Persimmon, San Marzano
SMALL FRUIT Black Cherry, Grape, Juliet, Sweet Million
Peppers quarts $3 SWEET Cute Stuff Red, Purple Beauty(in 6-pack $3), Shishito, Fushimi
MILD Anaheim, Ancho/Poblano, Fresno, Padron
HOT Caribbean Red, Jalapeno, Serrano, Thai
Other Vegetables quarts $3 Cucumber Burpless
Eggplant Asian long
Squash Zucchini dark green
Tomatillo Verde
Herbs quarts $3 extensive selection includes a lot of Basil and a few French Tarragon ($4)
NEW HARDWARE
10-gallon Black Plastic Nursery Pot $8 This is a nice size to grow a tomato plant or other vegetable.
Bamboo Trellis (obelisk) $5
This is tall enough to train a medium size tomato plant. |
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Please visit us at our farmers market locations. EVERY FRIDAY 9am-1pm\ Mission Viejo Farmers Market
Mission Viejo Library 200 Civic Center Drive, Mission Viejo Exit 5 at La Paz going east, right on Marguerite, right on Civic Center
EVERY SATURDAY 9am-1pm Old Towne Orange Farmers & Artisans Market
Historic Villa Park Orchards Packing House at Chapman College 304 N. Cypress Street, Orange 3 blocks north and 4 blocks west of the traffic circle (Glassell X Chapman) in Orange
EVERY SUNDAY 10am-2pm The Great Park Farmers Market
The Orange County Great Park, Irvine Exit Sand Canyon, turn south on Marine Way (parallels east side of 5) follow the signs
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26285 Verona Place
Mission Viejo, California 92692
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