Elisabeth C. Miller Library

Gardening Answers Knowledgebase

Search for gardening questions with researched answers, plus gardening tips, book reviews and recommended websites.

Browse the Knowledgebase

 


Recently Added Questions

Question:

One of my favorite autumn things to do is shuffle through the leaves of every katsura tree I pass. What causes that enticing burnt sugar smell? Are there other trees that smell like this?

Answer:

As the leaves of katsura trees (Cercidiphyllum japonicum) begin their process of decay, they are releasing molecules of maltol into the air and conjuring up scents reminiscent of toffee, cotton candy, or—as the German common name Kuchenbaum and the French arbre à caramel suggest--baking cake and caramel.

Maltol is also found in pine needles and lark barch, but it is most famously noticeable in katsura trees as they begin to turn color and the complex sugars in their leaves break down.

Question:

It's late September and my raspberries are done producing fruit. The canes are really tall. How should I go about pruning them?

Answer:

According to Linda Gilkeson's Backyard Bounty: The Complete Guide to Year-Round Gardening in the Pacific Northwest (New Society Press, 2018), the simple method is to wait until the dormant season and cut down canes that bore fruit last year. (You can tell these canes by their rougher and darker grey bark, compared to the lighter and smoother canes of the last growing season.)

This will work for summer-bearing as well as everbearing varieties, but some choose to prune everbearing (also called primocane-fruiting) raspberries in two stages. An everbearing raspberry is one that produces fruit in the early fall of the first year on their primocanes. It then fruits a second time, in June, on buds below those which fruited the previous fall. In the dormant season, prune off only the top part of the canes that have fruited, and let the remainder fruit next summer.Then you can prune out the whole spent cane the next winter. Try to keep only five to ten new canes per plant.

This Oregon State University Extension guide to Growing Raspberries in Your Home Garden may also be helpful to you.

Question:

It's late August, and some of my newly harvested Akane apples have a strange condition. From the outside they look normal, but when I cut into them, there are areas that look transparent and watery. They taste fine, but their appearance is kind of unappealing. What is causing this? Is there anything I can do to prevent it?

Answer:

What you are describing sounds like a condition called water core, where the plant tissue has started to break down. According to Washington State University’s Tree Fruit Research and Extension Center there are many potential causes of the condition. Certain varieties are more susceptible than others. "Advanced maturity" (i.e., apples that have been on the tree a bit too long), and a lack of calcium may also be a factor. We have had a hot summer, and intense sunlight and heat may also have contributed. On the plus side, the watery areas tend to taste sweeter than the rest of the fruit, and people in some parts of the world (such as Japan ) actually seek out watercored apples for just this reason. The main problem is that affected fruit will not last long in storage. You may want to test your soil to detect any nutrient imbalances and then amend the soil accordingly.

Question:

Some of the cucumbers I am growing and harvesting taste just fine, but some are really bitter—I wonder if I should even be eating them. What causes this, and are they safe to eat (not that I want to)?

Answer:

What you are describing actually has a name, toxic squash syndrome. It can affect plants in the Cucurbit family (so not only cucumbers but also zucchini, winter squash, and even melons). Oregon Health & Science University's fact sheet about this problem says that the cucurbitacins produced by plants in this family may have benefits for the plants themselves, warding off insects. But in humans, excessive cucurbitacin can cause digestive distress. Wild plants tend to have higher levels of this naturally occurring substance than varieties bred for human consumption. Still, environmental factors (such as uneven watering or fluctuations of heat and cold) can cause normally tasty cucurbits to turn bitter.

An article from North Carolina Cooperative Extension, "What Makes My Cucumbers Taste Bitter," says that cucurbitacin is mostly found in the leaves, stems, and roots of the plants but it can spread to the fruit as well. In your cucumbers, the highest concentration is likely to be in the skin and just below the surface of the skin. "Misshapen fruits are more likely to be bitter than well-shaped fruits. Some scientists even think that varying levels of fertilizers, plant spacing and irrigation frequency may also affect cucurbitacin levels. Bitterness seems to vary with the type of cucumber grown."

Because of the potential for unpleasant side effects, I suggest not eating the rest of a cucumber (or any other member of the Cucurbit family) if the taste is bitter.

Question:

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?

Answer:

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.