best time to fertilize rhodies, azaleas, and roses

Is it okay to fertilize my rhodies, azaleas, and roses in September? I missed
doing it in August.

Generally speaking, it is best not to fertilize your shrubs after mid-summer. The tender new growth that results is susceptible to frost, disease, and insects just at the time of year when the plant is beginning to shut
down. This is also true of roses, which are even more tender and susceptible than rhododendrons and azaleas.

An article by Terri Richmond (British Columbia) on the American Rhododendron Society website, entitled Fertilizing Rhododendrons the Organic Way supports the practice of fertilizing in spring. (Keep in mind that azaleas are in the same genus as rhododendrons.)

Oregon State University Extension suggests that budbreak in spring is a good time to fertilize roses, just as new growth is beginning. Stop fertilizing in late summer. Oregon State University also weighs in on fertilizing rhododendrons (if needed, in spring shortly after flowering, and preferably with organic fertilizer).

lack of flowers in star jasmine vines

I bought an established, white star jasmine perennial vine one year ago. I was told I could plant it in an extremely large pot and expect to enjoy blooms for about 3 years, but it has not bloomed, nor does it have any buds. It has no pests or blight of any kind. It gets full sun in the morning and partial during the day, and full again in late afternoon. It has always had sufficient water. What’s wrong? When do they normally bloom? Was I given inaccurate information?

I am assuming the star jasmine is Trachelospermum jasminoides, as shown in this image from Missouri Botanical Garden.

Failure to flower can be due to a number of causes, as described in this link from University of Vermont Extension.

My top guesses for what may be causing the lack of flowers would be exposure to
severe cold in the winter, or over-fertilizing with a nitrogen-heavy fertilizer.
The light exposure you describe sounds fine for this plant. In the Pacific
Northwest, it flowers mainly from spring to early summer. This link to
a Seattle garden writer’s site has cultural information appropriate for this
region (I don’t know where you are writing from).

growing moss indoors

Can you provide me with information on growing moss indoors? Also, do you know if Tolmiea is known for being fragrant?

Here is an article(now archived), “Indoor Gardening with Moss” by Robert Paul Hudson, from the Eugene Daily News. The author provides directions on maintaining a small terrarium with moss.

The web site Bizarre Stuff is another resource.
Excerpt:

Mosses can be grown in terrariums fairly easily. Collect moss from an
area where it is okay to do so and transport in plastic sandwich bags.
Sprinkle with water and seal the bag if you won’t be setting up the
terrarium right away. Use a large, clean glass jar with a tight fitting
lid. Lay it on its side in a shallow box or on a stand so that it will
not roll. Place sand and pebbles about 1/2 inch thick in the bottom of the
jar. On top of this place some of the soil from the same place where the
moss will be collected, or mix a soil of charcoal, light gravel, leaf
mold and garden soil. The soil should be level with the opening of the
jar. A little sulfur scattered on the soil will help to prevent mold from
growing. Plant the moss by pressing it into the soil. Water the
terrarium, screw the cover on, and place it in a shady place. If it seems
too wet, leave the lid off for a few hours to allow some of the water
vapor to escape. Eventually you will get the balance of water just right,
and the moss should thrive. The terrarium should sustain itself for
several weeks or months without needing additional water if the lid is
kept tightly on. If conditions are just right, the moss may eventually
send up little stalks. Some of these stalks form spores that will fall to
the soil and germinate into new plants.

The January 2007 issue of Better Homes and Gardens has an article,
“Pleasant Under Glass,” by Suzy Bales. Here is an abstract: The article
highlights the fragile beauty evoked by glass gardens or terrariums.
Everyday containers such as carafes and vases can make ideal terrariums.
Featured in the article is an antique terrarium that becomes a stage for
a miniature woodland garden. It has flowering Cape primrose,
rabbit’s-foot fern, golden club moss and black and dwarf mondo grasses.

The January 2003 issue of Sunset has an article by Kathleen Brenzel,
“Serene Greens,” on miniature indoor landscapes:
Presents ways in creating a miniature indoor landscapes. Use of copper
trays in Irish and Scotch moss; Dimension of the ceramic cache pots for
mini bog plants; Amount of water used for hyacinth floats.

Now on to Tolmiea. I consulted several reference books and online plant databases, but none mentioned fragrance as a quality for which this plant is known. This does
not necessarily mean it has no fragrance, only that it is not notable.

on the safety of pickled walnuts

Is it safe to eat pickles made from unripe walnuts (including hulls)? Are some types of unripe walnuts safe to eat and others not safe? I am not sure what kind of walnut is in my garden.

I am also a bit worried by articles I found online which say that juglone from walnuts can cause cell damage. Maybe I should skip this culinary adventure?

Pickled walnuts (from English walnut, Juglans regia) are a traditional British delicacy. The Royal Horticultural Society even mentions them. Alys Fowler’s book, The Thrifty Forager (2011), says the walnuts for pickling must be picked in early summer before they harden. Traditionally, walnuts for pickling were harvested June 15, St. John’s feast day. The famous 16th century herbalist John Gerard said, “the green and tender Nuts boyled in Sugar eaten as a Suckad, are a most pleasant and delectable meat, comfort the stomacke, and expell poison.”

All walnut species have edible properties, though black walnut may be more bitter than English walnut. Edible East Bay published an article by Kristen Rasmussen in summer 2015 on pickling green walnuts from a native Californian species of walnut, Juglans californica.

Anyone who is sensitive to walnuts probably should avoid the pickled ones, too. Like many plants, walnuts have both edible uses and toxic properties. If you do not consume large quantities of walnuts (pickled or otherwise), I do not think there should be dire medical consequences. Toxic Plants of North America, 2nd ed., 2013 (Burrows and Tyrl) has a section on walnut (Juglans). The main toxicity concern discussed is that to horses, and in their case, it is mainly due to the use of walnut wood shavings in horse stalls.

A word about finding random articles on the internet: Context matters, and the citation you found about cell damage is in the context of using juglone (administered in a medical research facility) to kill cancer cells. It is not the context of everyday consumption of walnuts. Reliable sources are hard to find via the internet, and I would view with skepticism any site that is primarily commercial and does not cite trustworthy sources.

I could not find any references to the effects of pickling on the chemical composition of walnuts. Certainly, pickling (like any form of food preparation) will have some effects on nutrients. But since pickled walnuts are likely an occasional snack and not a staple upon which one’s diet is founded, there is no cause for concern.

on dodders

While hiking on San Juan Island, I saw these strangely beautiful, fluorescent orange clumps of hair-like substance (plant? fungus? something from outer space??) interwoven through the succulent-looking marsh plants. Can you tell me what this is?

That weaving (or strangling!) habit you describe calls dodder to mind, and there is a native coastal salt marsh dodder in that area called Cuscuta pacifica. Dodder is related to morning glories (the plant family Convolvulaceae). It is a rootless parasitic plant with nearly no chlorophyll and barely any leaves, and cannot photosynthesize on its own. It sustains itself by twining around other flowering plants and infiltrating their tissues with specialized branches on its stems, and coiling around them repeatedly as it grows. It may even be able to “smell” potential host plants.

Dodder can weaken its host plants, rendering them vulnerable to disease. However, there is some evidence that by thinning out the dominant host plants in a given area, it makes room for other species to take hold, increasing diversity.

The Washington State Noxious Weed Control Board lists a non-native species (Cuscuta approximata, smoothseed alfalfa dodder) as a Class C noxious weed, but it is not found in the area where you were. It is mainly a problem in agricultural land east of the Cascades. Dodder has various unfriendly nicknames in farming land: Devil’s Guts, Witches’ Shoelaces, Strangleweed, to list a few.

a flower called ‘town hall clock’

While reading a book on British woodlands, I came across a reference to a flower whose common name is ‘town hall clock.’ Can you tell me what plant it is, and why it has this name?

Townhall Clock’s scientific name is Adoxa moschatellina, in the Adoxaceae family. Other common names for this native British wildflower are Moschatel, Five-Faced Bishop, Muskroot, Tuberous Crowfoot, and Hollowroot. All of those names are descriptive of various aspects of the plant’s appearance, but the name Townhall Clock is evocative of the way this pale yellow-green early spring flower rises up on a slender stem. According to Sarah Raven (in her book Wild Flowers, Bloomsbury, 2012), four faces of the flower are “arranged as if on the surface of a cube, the fifth facing upwards.” The aroma of the flowers is musky, or like “elder blossom with a bit of almond.”

There are some detailed photos of it on this Finnish plant identification website. Despite the name Townhall Clock, it’s a subtle flower that might easily be overlooked. In fact, its genus name means “without glory,” due to its unshowy blooms.

on fertilizing peach trees

We have a white peach tree that was just OK this year. I am wondering what I can do to get the most out of it next year – what is the best fertilizer for peaches?

According to Sunset’s Western Garden Book of Edibles (2010), peach trees may be fertilized with a 10-10-10 complete fertilizer (the numbers correspond to N-P-K, nitrogen, phosphorus, potassium) at bud break in late March. “Give young trees 1/2 pound per year of age and give mature trees up to 5 pounds (for full-size, full-grown trees). Spread fertilizer evenly over the entire root zone.”

Washington State University Extension has general information on fertilizing for home orchardists. Here is a relevant excerpt:

“Nitrogen is not needed in most of western Washington since we have such high levels of organic matter in our soil, and it is continually released during the summers. Nitrogen controls growth. With excess we get rank growth. Fruit maturity is delayed; and storage life of apples and pears is reduced. Peaches need more nitrogen so applications may be necessary.”

on the parasitic plant dodder

I’m doing a science fair project on dodder plant and I’m seeking information about the plant, and a source of seeds or plants for the project.

Dodder is a parasitic plant that lives on crops, ornamentals, native plants, and weeds. Because it has limited chlorophyll, it can’t make enough food to support
itself, and so relies on the plants it colonizes for nourishment. It belongs to the genus Cuscuta, in the family Convolvulaceae (same family as morning glory). It was formerly referred to as Grammica.

Perhaps the reason that seeds and plants are not readily available is that dodder causes great damage to the plants it parasitizes. The U.S. Department of Agriculture’s plant protection and quarantine office states that “products, including foods, containing whole dodder seeds (Cuscuta spp.) are prohibited entry into the United States. APHIS regulates whole dodder seeds, both as a parasitic plant pest under Title 7 Code of Federal Regulations (CFR), Part 330 and as a Federal noxious weed under Title 7 CFR, Part 360.”

Here is additional information from University of California, Davis’s Integrated Pest Management website. Dodder is sometimes referred to as the “Vampire Plant,” as this University of Florida Extension page explains. Although your project, safe within the confines of a lab or classroom, might pose no threat, it is not legal to sell Cuscuta seeds or plants in the U.S.

harvesting rooftop runoff water for vegetable gardens

I need to replace my roof, and I am thinking of installing asphalt or composite shingles because they’re what I can afford. I planned to capture rain water to irrigate my vegetable garden, but I’m concerned about toxicity. Is runoff from the shingled roof likely to be toxic?

I would not recommend using reclaimed rainwater from an asphalt shingle roof for any edible crop. Asphalt is petroleum-based. The runoff might be acceptable for ornamental plants, but the fact that asphalt or composite shingles tend to shed tiny particles means that those particles would be introduced to the soil around your crops.

An article from North Carolina State University Extension discusses “Water Quality of Rooftop Runoff.” It doesn’t specifically mention asphalt, but I don’t think it would be wise to use the reclaimed water on food crops.

Green Living Journal (now archived) has an article about roofing materials, and discusses asphalt shingles as well as alternatives.

The National Gardening Association site has a report, no longer available online, that describes rainwater harvesting.
Excerpt:
“Water from the rain barrel is, of course, not potable, but some experts also raise concern about possible contaminants from rooftops that can make the water unsuitable for edible gardens. According to an article in Landscape Architecture magazine, asphalt shingles and other porous or rough roofing materials can hold particulates such as bird droppings and other debris, as well as heavy metals from the air, which then wash into the rain barrel. Wood shingles that are chemically treated to resist rot and algae can leach the chemicals into the rainwater running off the roof. Zinc strips that prevent moss build-up can also be problematic. Some large-scale rainwater collection systems are even designed to allow for the first flush of water off the roof — which carries the majority of the questionable substances — to be diverted.

“Other people dispute these risks and say washing your garden produce is all that’s needed. It’s a judgment call. I tend to research things to death so I think it would be interesting to have some of my rooftop runoff tested at the health department.”

There is a very detailed and technical document entitled “Roofing Materials Assessment” from Washington State Department of Ecology (2013-2014 study results) if you wish to pursue the topic further.

If installing slate, clay tiles, untreated wood shingles, or a green roof is prohibitively expensive, the best solution might be to landscape the garden in such a way that you can reclaim runoff from the roof for non-edible plants.

dividing and propagating Dierama

Could you provide some information on the propagation and division of Dierama (not sure if the species I have is D. pendulum or D. pulcherrimum. It has pink flowers and is also known as Angel’s Fishing Rod)? The clump has gotten large and I’d like to see if I can divide it now in fall.

The Royal Horticultural Society has an advice page on how to divide and propagate Dierama.

Excerpt:
Named cultivars can be propagated by division in spring or immediately after flowering; but this should only be undertaken occasionally as plants are slow to re-establish. Plants grow from corms that build up year by year into chains, similar to Crocosmia.

Lift plants and separate corms, reducing the foliage by half with secateurs.

Take care not to damage the brittle, fleshy roots.

Divisions take one to two years to flower freely again.

For an answer from local experts, I consulted Perennials: The Gardener’s Reference by Carter, Becker, and Lilly (Timber Press, 2007). The authors say that “it’s best not to transplant, divide, or groom in the fall.” Instead, if you must divide, do so in April or May and include several corms in each clump. You can also sow ripe seed at that time. Seed may be harvested by shaking the stems.