Salt Heliotrope: A Pretty, Invasive Weed You Don't Want
Plus, more details about other garden topics explored on Ep. 147 of the Garden Basics Podcast, including growing blueberries in water trough containers, and the "Autumn Joy" Sedum
On Episode 147 of the Garden Basics with Farmer Fred podcast, college horticulture professor Debbie Flower and I tackled a question from Connor, a listener who is growing hops in the San Francisco Bay Area. And he is curious about whether he should keep the ground cover growing beneath his hops:
Connor’s hop understory of salt heliotrope. Should it stay or should it go?
That’s Salt Heliotrope, Heliotropium curassavicum, which according to Wikipedia, is a species of flowering plant in the borage family. It is native to much of the Americas, and it’s an introduced (and sometimes invasive) species in much of the rest of the world. It thrives in salty soils such as beach sand, alkali flats, salt marshes and disturbed coastal sites. This plant should not be confused with its better mannered sibling, common Heliotrope (Heliotropium arborescens), an old-fashioned plant grown for the sweet fragrance of its flowers. The flowers are attractive to pollinators. one of the differences between the two: salt heliotrope has mostly white flowers, while the common heliotrope has mostly purple flowers.
“Heliotropium curassavicum is an aggressive weed that rapidly colonizes new areas, in particular on disturbed saline soils and coastal areas in arid and semiarid habitats. It forms dense monospecific stands that displace native vegetation and alter successional pathways. A combination of traits, such as high seed germination and seedling establishment rates in open areas, along with its ability to shift between sexual reproduction to clonal growth (i.e., adventitious root buds) are responsible for the invasiveness and rapid spread of H. curassavicum. H. curassavicum has become one of the most common weeds in the Mediterranean Basin and the Nile Delta, where it is regarded as a serious ecological and agricultural problem, but it is also listed as invasive in countries across Europe, the Arabian Peninsula, Africa and in Anguilla in the Lesser Antilles.”
And this map from the University of South Florida chronicles the invasive spread of salt heliotrope throughout much of the Western United States, as well as being found in parts of the South and Eastern seaboard.
The bottom line? University of California Cooperative Extension Farm Advisor Scott Oneto says:
“I would completely agree that heliotrope can provide a lot of benefit as a pollinator species but because it is a perennial herb with rhizome-like roots, one would want to be mindful and perhaps manage it carefully if grown with hops so it doesn’t compete for water and nutrients. Although hops have some deep roots, it is the shallower feeder roots that are responsible for most of the nutrient and water uptake. Depending on orientation of the hop plants, perhaps the heliotrope could be managed between the hop rows and kept out from underneath the hop plants.”
Livestock Water Troughs for Blueberries
I’m a big fan of using livestock watering troughs for growing blueberries. To find out more about using watering troughs for plants, listen to Episode 108 of Garden Basics.
Regarding using them to grow blueberries, here’s info from the Farmer Fred Rant blog page:
The development of southern highbush blueberry varieties meant gardeners in USDA Zone 9 could start growing this tasty fruit. Up until about 25 years ago, blueberry growing was relegated to the cooler, more humid climates of the United States. According to the UC Cooperative Extension, rabbiteye blueberries grow in the southeastern part of the country and thrive in hot, humid weather but are not cold hardy. Lowbush blueberries grow in the northeastern states and Canada. Northern highbush blueberries grow from Florida to Maine and the northern tier states and have a high chilling requirement that limits their adaptability.
Southern highbush blueberry varieties have a low-chill requirement and are heat tolerant.
Although they are self-pollinating, blueberry fruit set will increase and berries will be larger if two varieties are planted together. Most varieties grow 4 to 6 feet tall here. A few, such as Sunshine Blue (3'), are more compact.
A UC Master Gardener variety trial in Santa Clara (SF Bay Area) found that the following varieties grew the best, produced the biggest crops, and had good to excellent flavor: ‘Reveille’, ‘Misty’, ‘Sunshine Blue’, ‘Bluecrop’, ‘Georgia Gem’ and ‘O’Neal’. Other varieties that may also work well include ‘Blue Ray’, ‘Cape Fear’, ‘North Blue’, ‘Ozark Blue’, and ‘Sharp Blue’. In our USDA Zone 9 yard, we have had success with Sharp Blue, Jubilee, South Moon, Blue Ray, Sunshine Blue and Misty. The southern highbush blueberries will thrive in containers, as long as you keep a few basics in mind:
• Plant blueberries in a good-sized container. You can start them off in five gallon containers, but a 15-gallon or larger is preferable. We use watering troughs from the local farm supply store. With holes cut in the bottom, of course. • Give them acidic soil. Use a one-third mix of potting soil intended for camellias and azaleas, peat moss, and small pathway bark, along with a handful of soil sulfur. This will give the blueberries their ideal pH growing range of 5.5.
• Blueberries need consistently moist soil, but be sure the pot has good drainage.
Blueberry flowers
• Because containers can heat up here in the summer, place them where they can get some afternoon shade.
• Feed blueberries with an organic fertilizer. Apply during the blueberry-growing season, late winter through summer. Organic fertilizers such as blood meal, cottonseed meal, fish meal, and alfalfa meal can be applied at a rate of 1 pound per plant.
• Having several containers with different varieties will improve pollination and give you an extended harvesting season. If you want a sure choice for USDA Zone 9, go with Sunshine Blue. Although a smaller shrub (about three feet tall), it has very low winter chill requirements and tolerates higher pH soils better than other varieties.
Ripening Dates for the San Joaquin Valley (source: UC ANR)
• The University of California advises growers of blueberries in containers to replace the soil with fresh potting mix as well as root prune the plant every 3 to 4 years.
Pruning Blueberries. Even though most of the blueberry bushes intended for here only get about five feet tall, they would benefit from some judicious pruning. The timing is a matter of opinion and experience. According to the American Horticulture Society book, "Pruning and Training", blueberries should be pruned in late winter, when the fruit buds are readily distinguishable. Prune back the shoots growing horizontally and any weak growth, cutting to an upright shoot or low bud. Prune out the oldest and weakest wood near the base of the plant to encourage strong new growth and remove any growth spreading out toward the ground. Cut out no more than a quarter of the bush annually.
However, as we know, all gardening is local. That pruning advice is intended as general guidelines for a nation of blueberry growers. What about the blueberry gardener here in the Central Valley of California and other warm climates?
Tom Spellman of wholesale blueberry grower Dave Wilson Nursery, advises pruning back the plants after harvest in the summer, to allow new growth to develop during the rest of the year and set fruiting buds that will be ready to produce next spring. Prune those plants back in winter, and you will be pruning out next year’s harvest, advised Spellman.
And, how about another opinion? Blueberry branches have a limited number of productive years, perhaps two or three. Ed Laivo of wholesale grower Burchell Nursery says to remove them after Year Two. "For major pruning, I wait until February, before the buds open," advises Laivo. "Then, I'll prune back the plant lightly after harvest to keep the plant in bounds."
Contrary to the advice in the American Horticulture Society book, Laivo says that the winter pruning can be as much as 50% of the plant. "But try to remove totally any branch that is over three years old. Those won't be very productive. By pruning those out, you'll spur new branch growth at the base."
And if a blueberry planting is in your future garden plans, Laivo says to get more than one. "Blueberries will yield a much bigger crop when paired with another variety," he says.
Laivo also advises planting blueberries in large containers, not in the ground. That way, you can give the plants the exact soil they need. "The trick is the soil mix," says Laivo. "Blueberries like a low pH around 5.5. And they like to grow in actively decomposing organic matter."
That's an important point for those who plant the southern highbush blueberries in the ground. Blueberries benefit by incorporating well-decomposed organic matter into the soil. And the best organic amendment? Compost. Blueberries are in the same family as azaleas and rhododendrons (Ericaceae); wherever those plants are thriving in your yard is probably a good location for the southern highbush blueberries.
In a year or two, your biggest concern after planting these shrubs may be: what can I do with all the fresh blueberries?
How about blueberry smoothies! Our recipe for this quick to make treat: 1 Cup Blueberries 2 Cups Orange Juice or Apple Juice 1 ripe banana 1 Cup Yogurt 1/4 Cup skim milk 1 Tbs protein powder (optional) Blend, and enjoy!
The Plant of the Week: “Autumn Joy” Sedum
Buddy the Dog, guarding the Autumn Joy Sedum
“Autumn Joy” sedum, (a hybrid of Sedum telephium), has a long showy season throughout much of the United States. It dies back in the winter, but before that, the umbrella-like flower heads put on a great show, with the bright salmon pink flowers turning color over the course of several months to a shade of russet. It prefers full sun, and regular to moderate water. In the Plant of the Week segment on Episode 147 of the Garden Basics podcast, UC Davis Arboretum Superintendent Emeritus Warren Roberts says:
“It does die back. The seedheads which looked very nice, will start to look a little bit disheveled and at that point I just clip them back to the ground. And already, you'll see the new growth coming up. So it's an easy plant, it's successful in most gardens. It’s a useful plant in the perennial border and easily propagated by divisions. This is one of those ‘over the back fence’ kind of plants that has been shared amongst people for hundreds of years.”
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Nice touch with K.C. and the Sunshine Band.
Please come back to the radio show I miss it so much.