Tips for container success: soil, pots, plants, tending methods
Much frustration surrounds growing plants in containers outdoors, probably due to exaggerated expectations. If you want safety where container planting is concerned, confine your choices to cactuses and succulents. You will not need to change the soil except occasionally and some of these plants may remain in the same pot in the same soil for many years. On the other end of the spectrum, growing fruit trees in containers presents challenges like none other, and woody perennials of any kind for that matter, including most roses, are not the most suitable candidates for container growing.
“Containers in the Garden” (Cool Springs Press, 2022), by Claus Dalby, provides recognition, I venture to say, that the most rewarding plants for container growing are annuals and herbaceous perennials. The latter consist of plants that grow from bulbs and their allies, namely rhizomes, tubers and corms. Dahlias receive special attention in this volume and it may be impossible to put this book down without picking up some dahlia tubers at your local nursery. At Armstrong's Nursery, you can find a package of two giant dahlias for $9.99, and at Ace Hardware on Sepulveda Boulevard in Van Nuys, you can procure 10 small dahlias for $11.99 and, as long as you're there, check out the sale of 50 gladiolus corms for $10.19. Or place an order for dahlias and gladiolus from an online source (tulipworld.com, dutchbulbs. com or hollandbulbfarms.com). Planted in the spring, dahlias will display their large, silky inflorescences — whether pom-poms, dinner plates or something in between — in summer and fall. Gladiolus, named for its terminal flower buds that come to a point (“gladius” means “sword” in Latin), will bloom in the summer.
“Containers in the Garden” is replete with lavish photographs of the author's potted creations, all of them bulging with blooms. His containers are strictly “light terra cotta clay.” Dark terra cotta, although less expensive, is brittle and after a year or two, based on my experience, generally crumbles. Also, light terra cotta “takes patina [the green film that forms on the surface of bronze, copper and clay] well.” It is true that plants in terra cotta pots must be watered more frequently than those in ceramic or plastic pots, the reason being that clay is porous and water escapes through the sides. The benefit of clay is that it allows the roots, which need oxygen as much as you or I, to breathe due to the air exchange that clay affords. In clay pots, plants simply grow more quickly and in better health than in other container types.
“With soil, quality costs, so don't go for the cheapest product,” the author advises. “Check the soil: pick up a handful of potting soil and close your hand tightly around it. Then open your hand again. If the soil is compressed, it will not be suitable, but it should also not be so loose that it falls apart. An intermediate consistency is appropriate. When doing this little test, it is important that the bag has not been opened so long that the soil has become dry. It should be slightly damp.” The exceptions here would be cactuses, succulents, California natives and citrus trees, which, when container-grown, are best planted in a cactus mix. Otherwise, your mix should contain vermiculite or perlite — “small particles of expanded volcanic rock that help to hold water and fertilizer.” Finally, it should contain compost “or another longacting fertilizer — enough for a whole season” which means six months. If such a fertilizer is not included in the potting soil you select, you can mix a slow-release fertilizer that lasts six months into the soil after removing it from the bag.
In terms of the particulars of planting bulbs, the author recommends this protocol: “Put 2-4 inches of pebbles in the pot, and then fill it about halfway with potting soil. The amount of potting soil is adjusted so that the bulbs can be placed at a depth three times their height.” After placing the bulbs, “Fill up with potting soil. Finally, water well.” I should mention that the pots recommended here are large: 12-24 inches in diameter with comparable depth. In large containers, make sure to leave up to 2 inches between the top of the soil and the rim of the pot so you can water adequately without concern about overflow. When it comes to watering, “a hose with a watering wand makes the job relatively simple.”
Based on my experience, the bigger the pot the better, since roots have room to grow and the frequency of watering is reduced as compared to smaller containers. A bonus, of course, is the dazzling effect created when large containers are brimming with blooms, making an unforgettable impression when each container is filled with a single type of bulb displaying a single flower color that is repeated. For example, if orange is your color, you could have a mass of orange dahlias in one pot next to a mass of orange gladioluses in another next to a mass of orange tuberous begonias in another, interspersed with orange canna lilies.
A small number of woody plants are singled out by the author for container growing: Japanese maples (Acer palmatum), angel trumpets (Brugmansia), miniature roses and kumquat trees. Hydrangeas are also featured, although they are more semi-woody than woody.
Have you had success growing plants in containers outdoors? If so, please send along details of your success, with photos horizontally oriented if you have them, so I can share your experience with readers of this column.
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I have found a superb site for plant identification. There is no registration or other mumbo-jumbo to interfere with submission of your images, which may be uploaded without ceremony. You are given several identity options for the plant you submit, ranked by the likelihood of your plant matching each option. Access the site at identify.plantnet.org.
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I asked in a previous column if anyone had found a way to prevent birds from preying on their figs and received the following response from Nancy Swan, who gardens in Newport Coast: “Birds and crows wake up a lot earlier than we do and go after the figs, stealing or sampling them even before they are ripe. But that is not all that makes the ripe fruit unusable to us. We also have to fight ants, bees, critters and insects. Bees have been the biggest problem because they enter the fruit from the hole at the bottom before they are ripe enough for people to eat. They eat figs from the inside out, often invisibly. They leave behind little shriveled punching bags sucked dry hanging from the branches. Even if they only enter briefly, they secrete something that starts to break down the fig at the sweetest bottom part, turning it sour and inedible. Inexpensive organza fabric gift bags, readily available on Amazon and eBay, have done the trick. 6” x 8” size is ideal, but 5” x 7” is also acceptable. It takes only a little time, and is easy to do. The fruit ripens in the bag, and is pristine when we pick it. No bird droppings, no pecks, and no bees. We have even washed good bags and used them a second year. This also works for our dwarf apple, pear and mandarin orange trees.”
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In response to a column on purple flowers, Shelly Verlinder, who gardens in Upland, sent me a photo of a breathtaking wisteria in full bloom. It has been trained into a standard (single-trunk) tree that is “on a slope with full sun.”