Rue: the Herb that Shouldn’t Be

20170628A Leonora (Ellie) EnkingFlickr

Ruta graveolens ‘Jackson’s Blue’: a very blue-leaved variety. Photo: Leonora (Ellie) EnkingFlickr

These days, everyone loves traditional plants, the ones our ancestors grew. Garden writers keep dragging old plants out of mothballs and presenting them as something we should rediscover. But some of them should maybe have stayed lost in the mists of time … and that could be the case with rue.

Rue (Ruta graveolens), often called garden rue or herb-of-grace, is a plant with a long history of medicinal use and is also used as a condiment due to the acrid taste it gives to food and drinks. In addition, rue has the reputation of repelling cats and perhaps other mammals (that’s far from sure, though). This encourages gardeners interested in healing, aromatic or repellent plants to try growing it and thus rue is now fairly easy to find in many garden centers. Just look in the herb section … but planting it is maybe not such a good idea.

Of course, rue is certainly pretty enough: with its upright to mounding habit, its blue-green deeply cut leaves and its small greenish-yellow flowers, it can easily be used as an ornamental plant in a flower border. And several people automatically include the plant in the vegetable garden, hoping to keep undesirable mammals at bay.

But there are several problems with these kinds of use.

The Downsides to Rue

Rue is not your typical harmless herb, one you can just plant and enjoy. It packs quite a negative punch and you really should know about its flaws before you plant it.

Effet de la rue

A severe skin irritation due to contact with rue. Photo: Vincent, Wikipedia.

Many people find themselves suffering from skin irritation after they handle or even just brush against rue. Symptoms can include redness, a burning sensation and blisters. That’s because rue has phototoxic sap due to the furanocoumarins it releases.

Phototoxic means that irritations only appear when the skin is first exposed to the plant, then to the sun. Even if you roll around naked in rue in the evening or on a cloudy day, there’ll be no negative reaction, nor will there be if you wash your skin with soapy water after contact. But going to pick vegetables on a sunny day in a garden with a rue border has sent some people to the hospital! Children are generally more sensitive to furanocoumarins than adults and should never be allowed to touch this plant.

Always wear gloves when handling rue!

Rue is also poisonous. This can seem surprising, given that this plant has a long although limited use in Mediterranean cuisine, but it’s the dose that makes the poison. A single chopped rue leaf added to a salad is not likely to be harmful, but eating too much will cause gastric distress and has sometimes led to death.

As for its medicinal uses, and there were many (it was supposed to keep away the plague, for example), most have fallen by the wayside over time and are no longer considered viable. Even back when rue was a major medicinal plant, it was never so much a curative as an abortive. Legend has it that Julia Titi, the daughter of the Roman emperor Titus, died after consuming it during a forced abortion.

Although rue is no longer used in modern medicine, some herbalists still claim a host of uses for it. If someone recommends it to you, think twice!

Also, rue stinks. And that’s probably best, because its pestilential odor paired with its pungent taste dissuades humans (and animals) from consuming it in excessively large quantities.

Its reputation as an animal repellent (people regularly claim it will keep everything from birds to beavers out of the garden) is certainly exaggerated. A few mammals (some cats, for example, but not all) will avoid brushing against it, probably because of its smell, and very few will eat it, but that won’t stop them from just squeezing past. It loses any effectiveness at only 6 to 10 inches (15 to 30 cm) from the plant. To use it to keep animals out of your garden, you’d have to plant in a border all around the garden … and cross your fingers that the unwanted animal simply didn’t jump right over it. (The plant rarely reaches more than 27 inches/70 cm high in cold regions, up to 3 feet/1 m in milder zones.)

Then there is its invasiveness to consider. Originally native to the Mediterranean region, rue has escaped from cultivation in North America, South America and Australia and is considered a noxious weed in many areas. Is that what you really want for your garden?

If You Still Want to Grow Rue

20170628D Kurt Stüber, WC

Rue (Ruta graveolens). Photo: Pixabay

In spite of all its disadvantages, there many people who will still want to grow rue, sometimes because its use is traditional in their culture or because of their belief in herbal remedies. And it’s attractive to beneficial insects too, including pollinators. (However, so are many plants that attract beneficial insects, yet aren’t poisonous and invasive.)

If you have the right conditions, rue is not at all difficult to grow. It needs full sun and a well drained to dry soil that is neither too rich or too acid and it does fine in alkaline soils. It’s a short-lived perennial (4 or 5 years) that maintains itself by self-sowing. It’s fairly hardy, up to zone 5, although a bit of winter protection could be useful. In colder areas, you can grow it as an annual.

Rue: now that you know more about it, you can decide whether you want to grow it!

Foam on Your Plants? It’s Just Frog Spit!

20170627A MuPaily, WC

This strange bubbly froth is called frog spit. Photo: MuPaily, Wikimedia Commons

No, not real spit from a frog, but the cluster of small transparent bubbles in a whitish foam is instead caused by an insect called a spittlebug or froghopper, in the Cecropidae family (also in the newly created families Aphrophoridae and Clastopteridae), and goes by the name of frog spit, cuckoo spit or snake spit.

A generation ago, most curious children were in contact enough with nature to have examined the spittle and would have discovered on their own that there is a small pale green to yellow insect inside, but nowadays many children don’t venture far from the asphalt and concrete of the city. When they become young adult gardeners (and gardening has never been as fashionable among the younger generation as it is today!), they can be mystified by this weird froth. What is it and what to do about it?

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This spittlebug nymph is feeling quite naked with its bubble shelter removed. Photo: treegrow, Flickr

The insect found in the bubble shelter is the nymph of a spittlebug. Soon its birth, it pierces the stem of its host plant and uses the sap that flows from it to make the bubbles in question, inflating them with air from a special opening on its underside. Not only does this spittle conceal the nymph from predators, it insulates it from sudden temperature changes and prevents it from drying out. Moreover, the foam has an acrid taste, enough to keep even the most stubborn predators at bay.

There are over 850 species of spittlebugs throughout the world. In fact, if there are plants nearby, there are probably spittlebugs! Some are quite ubiquitous and will settle on almost any plant, either woody or herbaceous, but there are species that are exclusive to certain plant groups. In the average garden, you’ll most often see them on small fruits and such ornamental flowers as chrysanthemums, dahlias, mallows, roses, fuchsias and lavenders.

20170627C Charlesjsharp, WB

Adult spittlebug. Photo: Charlesjsharp, Wikimedia Commons

The adult is a small hopping insect, often brown or beige. It is seldom seen, for not only does its color help conceal it, but it leaps to other plants when people approach. When a spittlebug is ready to jump, it crouches down and takes on a froglike posture, whence the name “froghopper.”

The adult spends its summer feeding on the sap of plants. At the end of the season, the female pierces holes in a stem and deposits its eggs. They hatch in the spring and, with the return of favorable temperatures, form a bubble home. The nymphs feed on the plant for several weeks, molt a few times, then emerge as adults. The foam is then washed from the plant by the next hard rain. There is only one generation a year. Given the pest’s life cycle, the appearance of frog spit is often considered a sign of the arrival of summer.



Just add a bit of frog spit to the pot the next time you get the coven together to make a bit of brew! Illus.:

Our ancestors found frog spit a very mysterious product indeed, believing it was produced by frogs, cuckoos, snakes or even witches. In fact, frog spit has been a popular ingredient in witches’ brews over the centuries!

Damage Caused

A single spittlebug nymph causes little immediate damage. However, when there are several bubble shelters on the same plant, the growth and vigor of the plant may be affected and the leaves and stems may be deformed.

The real problem, though, is that spittlebugs can transport viruses from one plant to another and that the holes they pierce can leave an open wound on the plant that will be prone to microbial infestations.

It is, however, the adults who cause the most damage and their great mobility makes control difficult. The effect of a single nymph on a plant is minimal.

What to Do?

What to do when you see frog spit on one of your plants? You can simply ignore it if you want to, as it causes little damage. Or you can remove the nymph with your fingers or wash the spittle off with a strong stream of water, thus exposing the creature to the drying sun. When there is more than one patch of frog spit on the same plant, however, it’s best to remove them, as an accumulation of nymphs could damage the plant’s health.

Frog spit: a disgusting name, but it hides a most interesting little insect!20170627A MuPaily, WC

Watering Responsibly


20170626B Clipartix.comTrue enough, everybody wants a nice green garden, but there is no need to waste water by watering excessively either.

You have no idea how many people think that watering every single day is the only way to have delicious vegetables and beautiful flowers! Yet a thorough watering once a week is usually amply enough for most vegetable beds, flower gardens and lawns, although sometimes container plants may need to be watered more often.

Back to Basics

There is an age-old technique you can use to determine when to water. It’s so old that it undoubtedly dates back to when the first humans grew a plant some 12,000 years ago! Yet it works just as well today as it did then.

And here it is:

20170626ASimply stick your index finger into the soil to the second joint and feel the soil.

If the soil feels dry to the touch and there is no rain on the horizon, water abundantly for at least a few minutes to ensure that the soil is moist deep down and not just on the surface. Repeat the test in about a week to see if watering is needed again.

If the soil is still feels moist to the touch, wait a day or two, then repeat the test, only watering when it does feel dry.

Sometimes gardening is just sooo easy!

Is Treated Wood Safe in the Vegetable Garden?

20170625A JOe Mabel, WC

Raised vegetable bed with treated wood. Photo: Joe Mabel, Wikimedia Commons

There is a long-standing controversy in the field of organic gardening: can pressure-treated wood be used as part of an organic vegetable garden? Here’s what I know:

20170625B Lamiot, WC

Wood that isn’t pressure-treated tends to rot fairly quickly in contact with the soil. Photo: Lamiot, Wikimedia Commons

Pressured-treated wood sold in the US and Canada used to contain chromated copper arsenate (CCA). In the long term, this product released arsenic into soil, more under certain conditions than others. The fear was that the arsenic could be absorbed by vegetables and other edible plants and transferred to humans. And everyone knows that arsenic is toxic. In addition, burning wood containing arsenic is much riskier than using it in the garden!

In North America and in much of Europe, CCA-treated woods were removed from the residential timber market (they are still allowed for use in some commercial applications) sometime at the beginning of the 21st century (in early 2004 in Canada and the US and in 2006 in Australia, notably). Since then, two other products containing copper have been widely used in pressure-treated wood: alkaline copper quaternary (ACQ) and copper azole (CBA).

They contain no arsenic: it’s their copper content that helps to preserve the wood. Any treated wood will eventually leach some of its chemicals into the surrounding soil (again, more so in some soils than others). However, copper is considerably less toxic than arsenic. The risk to humans and warm-blooded mammals from copper-treated wood is considered minimal, but fish and insects are very sensitive to it (copper-treated wood should never be used in ponds or streams). Interestingly, human beings absolutely need copper in order to to survive, but in very small quantities.

Soil experts are essentially unanimous: they see no risk for humans in using copper-treated wood products in a vegetable garden, the amount of copper released being minimal and copper being considered essentially nontoxic unless present at extremely high levels. Despite this, accreditation agencies for organic products do not permit the use of wood treated with copper in certified organic vegetable production.

Curiously, they do allow the use of copper-based pesticides, including Bordeaux mixture, which release more copper into the environment than copper-treated wood ever could. Go figure!

What To Do?

So, should you use copper-treated wood in a raised bed vegetable garden or not?

I can’t pretend to be an expert in this field: I’m a home gardener, not an expert on chemicals! But I think enough information is out there for you to decide.

20170625C Lori L. Stalteri, Flickr.jpg

Many people don’t know if their raised beds were built with pressure-treated wood … and perhaps it really isn’t that important. Photo: Lori L Stalteri, Flickr

Do you opt for the convenience and reasonable price of copper-treated wood relying on scientific studies, will you stick with less expensive, non-treated wood even if that means replacing it every 7 to 10 years, or are you willing to pay top price for redwood or recycled plastic lumber so as to be as “organic” possible? That’s your decision.

Also, remember that, if it’s just a question of raised beds, you could use bricks, stones or cinder blocks to raise the bed above the surrounding soil. Or you could simply mound the soil and slope the sides, using no containing material whatsoever.

Some Other Possibilities

Wooden Decking Paint Wood House Deck Varnish

Coating even inexpensive softwood with varnish or paint will help it last longer … but some organic gardeners might object. Photo: Mega Pixel

There are still a few other possibilities. Like painting untreated wooden boards with some sort of waterproofing agent—paint, stain, varnish, etc.—so it will last longer. Unfortunately, few of these products are considered acceptable in the field of organic gardening, at least not if you’re growing vegetables commercially and hope to get your organic certification one day. (The criteria for organic certification are so stringent in most countries that the average commercial organic vegetable grower could never hope to obtain it.)

Untreated wood can, however, be painted with linseed oil. This treatment will help waterproof it… and linseed oil is one of the few waterproofing products that is 100% acceptable in organic gardening circles.

Alternatively, you could build the frame of your vegetable garden with pressure-treated wood (ACQ or CBA), then cover the inner wall with a sheet of plastic so that no copper from the wood ever touches the soil it contains. Many organic gardeners use this combination and feel fully comfortable with the result.

And If Your Vegetable Bed Is Already Framed with Treated Wood?

If your vegetable bed was installed after 2004 using treated wood, and you’re a concerned organic gardener, what should you do? This is a situation where there will always be divergent opinions. Even among people who take organic gardening very seriously, many would see nothing wrong with it. Maybe this is one of those cases where toeing the organic line too closely is being more Catholic than the Pope!20170625A JOe Mabel, WC

Keeping Ants Off Your Hummingbird Feeder


Ants will indeed be baffled  when you put an ant moat on your hummingbird feeder.

If there is any way ants can reach a hummingbird feeder, they will. They love slurping up the sugary nectar inside and the presence of a lot of ants will often keep hummingbirds away. There are a lot of ways you can dissuade ants from reaching your feeder, like hanging it from places they simply can’t reach (the middle of a clothesline, for example), but you can also solve the problem quite rapidly without moving the feeder by putting in a water barrier. Ants are very poor swimmers and hesitate to cross even the narrowest surface of water, despite the fact that there is delicious nectar just on the other side.

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One simple tool you can use to solve this problem is an “ant moat” or “ant baffle” designed specifically to use as a water barrier to keep ants away. Just install it above the feeder and add water to create a “moat” that ants can’t cross.

Some hummingbird feeders even have an ant moat incorporated into their structure: again, you just have to keep it full of water.

You’ll readily find both ant moats and feeders with a built-in ant moat online on Amazon or Ebay or in stores that specialize in birdwatching supplies.

Or Make One Yourself

You can also make your own ant moat barrier from products you probably already have at home.


Make your own ant moat from an aerosol can cap.

Just use an aerosol can cap (found on all sorts of products, from spray paint to pesticides) with a “double shell”, that is, with a small raised “cup” of plastic in the middle. Now drill a small hole through the center of the cap, one just wide enough so you can insert it onto the stem or wire from which the feeder hangs. Turn it so the cup faces upwards and skewer it onto the stem about 2 to 4 inches (5 to 10 cm) above the feeder. Apply some hot glue to the cap around the stem or wire so it stays in place.

Now add water to the reservoir formed by the inverted cap and the ants will no longer be able to cross to the feeder. It couldn’t be easier!20170624A

Garden Myth: Carrot Tops Are Poisonous


20170623A.jpgMany gardeners believe that carrot tops (carrot leaves) are poisonous. After all, don’t we usually cut them off and toss them into the compost pile when we harvest carrots?

In fact, though, not only aren’t they poisonous, they’re even edible … and quite tasty! Plus they’re rich in minerals and vitamins, notably in vitamin A, like the roots, but also six times richer in vitamin C plus a great source of potassium and calcium.

Carrot tops taste a lot like mix of parsley (a close relative) and carrot roots. Mature leaves can be bitter, but you can fix that by blanching them or cooking them. Or toss a few into a smoothie with a sweet fruit and that will hide any bitterness.

The young leaves are even better, as they have little to no bitter taste. So when you thin your carrots, just eat your thinnings, both root and leaf!

Here’s a recipe for carrot-top pesto you might want to try.

Ants in Your Plants?


20170622A.pngDon’t panic at the sight of little brown ants climbing onto your plants. These insects are completely harmless and do nothing to disturb plant growth.

However… the presence of ants often indicates another problem. That’s because ants feed on the honeydew emitted by aphids and mealybugs, insects that truly are a danger to your plants. Follow the ants’ movements and they will often lead you to a hidden invasion of truly nasty bugs.

A thorough treatment with insecticidal soap, repeated weekly for 3 weeks, will overcome the real problem! And you can thank the ants for showing you where the problem was!