When do foxgloves bloom?

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How do you get your beautiful foxgloves to return year after year?

There is a special trick to it. Here’s a little video that explains a very useful technique for getting seeds to drop and establish themselves in the right place,

Once upon a time, I had dozens of foxgloves in the garden. But over the years, they started disappearing, probably because of over-zealous weeding and fall cleanup.
So I was very happy to see foxgloves have made a comeback this year. We have some beautiful Digitalis purpurea as well as some exceptional white forms.

I will be allowing them to go to seed this year and will collect and sprinkle them throughout the garden and allow the seedlings to develop. Being biennial, foxgloves take two years to bloom, putting down their roots and producing leaves the first year, and flowering the following year.

I will also set aside some flats to germinate seedlings separately for planting out later.
Foxgloves are one of those plants we take for granted but miss the moment they disappear. It is really a case of not knowing what you’ve gone until it’s gone.

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Sally Tagg Pink and white foxgloves add an airy delicacy to cottage gardens.

Foxgloves are the classic choice to add height, heft and delicacy to an English cottage-style garden – but they are not without their issues.
All parts of the plant are poisonous, the pink and white ones are consummate seeders and the fat rosettes of leaves have a habit of taking over from some of your more precious border plants.

Once you have them, you should have plenty as they seed prolifically. If there is sun and bare, rich soil, you will be inundated if you don’t deadhead the spikes straight after flowering.

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NEIL ROSS The common foxglove (Digitalis purpurea) is great for adding height to a border.

The common foxglove (Digitalis purpurea) is the largest of its type: in exposed areas, you may have to stake the flowers, but they are perfect for adding vertical accents to garden borders.

Remove the flowers promptly and you will induce lower side shoots to emerge, sending up a second flush of flowers later in the year.

NEIL ROSS The strawberry foxglove is shorter and lusher than its purple cousin.

I love the simplicity of the straight mauve-purple colour, especially against purple-leaved cotinus and in shady corners.

The strawberry foxglove (Digitalis x mertonensis) is an unusual cross between the biennial Digitalis purpurea and the perennial Digitalis grandiflora, and is shorter and lusher than its purple cousin.

In lighter soils it is marginally perennial. Add plenty of leaf mould and grit to improve your chances of a yearly bloom.

Unusually for a hybrid, it comes true from seed. Kings Seeds sells it as foxglove ‘Strawberry Merton’.

Hardly the flamenco dancer you’d expect from the sun-drenched mountains of Spain, Digitalis parviflora is a sombre spire.

Its parts are precisely tailored, from the stunning rosettes of leaf in year one to the narrow spikes which take an excruciatingly long time to produce their tiny brown flowers.

NEIL ROSS The small-flowered foxglove (Digitalis parviflora) is a great choice for modern gardens.

Team it with delicate tiarella, maroon aquilegia and Eupatorium ‘Chocolate’ in a bright clearing. It’s perfect in modern gardens packed with schist, rusting iron and wispy bronze carex grasses.

The bellbird plant or Canary Island foxglove (Isoplexis canariensis) mightn’t be a true foxglove, but it’s so closely related that it’s now being crossed with herbaceous ones to stunning effect.

This waist-high, evergreen, if short-lived, shrub flowers from spring through summer and is a magnet for nectar-feeding birds.

NEIL ROSS The bellbird plant (Isoplexis canariensis) is closely related to foxgloves.

In cold areas protect it with evergreen trees or house walls and plenty of drainage if you want it to live beyond its first year. It’s available from Woodleigh Nursery.

The rusty foxglove (Digitalis ferruginea) is an exquisite spire packed with colours of bleached honey – each bell has a protruding hairy lip and insides scrawled with bronzy hieroglyphics.

It is short-lived as a perennial, so support the spikes with stakes and leave them to allow the seeds to ripen. Collect and sow the same summer.

NEIL ROSS The rusty foxglove (Digitalis ferruginea) has striking spires.

Like most foxgloves this beauty prefers a humus-rich soil, sun for at least half of the day and a bit of watering in dry summers.

From Western Europe and North Africa, Digitalis grandiflora is considered the finest of the truly yellow foxgloves.

It’s said to be short-lived, but my six-year-old colony is going strong.

NEIL ROSS The short-lived yellow foxglove, Digitalis grandiflora.

The spikes at 40cm fit well into smaller garden spaces and while the show can be rather brief – just 2-3 weeks – it’s worth it to have such an unusual colour combined with pretty leaves for the rest of the year.

In the wild, Digitalis purpurea is naturally very variable, but Digitalis ‘Pam’s Choice’ seems to have stolen the show.

Most of us are a sucker for a spotted foxglove, but in ‘Pam’s Choice’ the purple blotching is so thick that it oozes out of the flowers like raspberry jam on hot toast.

NEIL ROSS Digitalis ‘Pam’s Choice’ is a popular spotted foxglove.

Prevent plants from drying out, especially in late summer when new seedlings need moisture to germinate and swell, so they reach flowering size for next year. Available from Kings Seeds and Egmont Seeds.

Digitalis ‘Apricot Beauty’ (from Awapuni Nurseries) is perhaps less apricot and more pink with a blush of peach, but who am I to quibble?

It looks amazing teamed with the similarly coloured climbing rose ‘Phyllis Bide’.

NEIL ROSS Digitalis ‘Apricot Beauty’ is not a true apricot…. perhaps more of a pink?

Alternatively, set it against purple foliage, especially the leaves of a dark elderberry that has flat peachy flowers that match the colour but give a lovely contrast in shape.

NZ Gardener

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Foxglove

Description

Foxglove, also called Digitalis purpurea, is a common biennial garden plant that contains digitoxin, digoxin, and other cardiac glycosides. These are chemicals that affect the heart. Digitalis is poisonous; it can be fatal even in small doses. It was the original source of the drug called digitalis.

Foxglove is a native of Europe. It was first known by the Anglo-Saxon name foxes glofa (the glove of the fox), because its flowers look like the fingers of a glove. This name is also thought to be related to a northern legend that bad fairies gave the blossoms to the fox to put on his toes, so that he could muffle his footfalls while he hunted for prey. The legend may account in part for some of the common names of digitalis: dead man’s bells, fairy finger, fairy bells, fairy thimbles, fairy cap, ladies’ thimble, lady-finger, rabbit’s flower, throatwort, flapdock, flopdock, lion’s mouth, and Scotch mercury.

Foxglove was first introduced to the United States as an ornamental garden plant. During the first year, foxglove produces only leaves. In its second season it produces a tall, leafy flowering stalk that grows 3–4 ft (0.9–1.2 m) tall. In early summer, many tubular, bell-shaped flowers bloom; they are about 2 in (5.08 cm) long and vary in color from white to lavender and purple.

Foxglove was originally used for congestive heart failure and atrial fibrillation (chaotic contractions across the atrium of the heart). Foxglove helps the muscles of the heart to contract, reduces the frequency of heartbeats, and lowers the amount of oxygen the heart needs to work. The cardiac glycosides in foxglove block an enzyme that regulates the heart’s electrical activity. The dried leaves, ripe dried seeds, and fresh leaves of the one-year-old plant, or the leaves of the two-year old plant are the parts that were used in medicine.

In spite of its use in the past, foxglove has been largely replaced as a heart medicine by standardized pharmaceutical preparations because it is one of the most dangerous medicinal plants in the world. Foxglove is, in fact, a useful example of the importance of standardization in testing the efficacy and possible toxicity of present-day popular herbal medicines. Its sap, flowers, seeds, and leaves are all poisonous; the leaves, even when dried, contain the largest amount of cardiac glycosides. The upper leaves of the stem are more dangerous than the lower leaves. Foxglove is most toxic just before the seeds ripen. It tastes spicy hot or bitter and smells slightly bad.

In folk medicine, foxglove was first used in Ireland. Its use spread to Scotland, England, and then to central Europe. It was taken to treat abscesses, boils , headaches, paralysis, and stomach ulcers. It was also applied to the body to help wounds heal and to cure ulcers. It has not been proven to be an effective treatment for any of these ailments.

In 1775, William Withering, an English doctor, first discovered the accepted medicinal use of foxglove. He identified digitalis as a treatment for swelling or edema

associated with congestive heart failure. Withering published a paper in 1785 that is considered a classic in the medical literature. Foxglove was used to treat heart disease during the eighteenth and nineteenth centuries.

General use

Foxglove is no longer used as a heart medicine because the therapeutic dose and the lethal dose are very close. Seasonal variations in the level of cardiac glycosides in the plant make the safe dose impossible to estimate except by an experienced physician and prescriber of the herb who monitors the patient on an hourly basis for signs of overdose. Few living doctors and herbalists can safely use digitalis as a plant extract. Specific standardized doses of pharmaceutical digoxin are used instead. Even so, patients receiving the drug must be closely monitored.

Preparations

In present-day usage, foxglove is used as an ingredient in a class of heart drugs called digitalis. Digoxin (Lanoxin) is the most common drug made from digitalis. Digitalis is usually taken orally, as capsules, as an elixir, or as tablets. It can also be given in an injection.

Precautions

Used improperly, foxglove is deadly; it can make the heart stop or cause a person to suffocate. Eating any part of the plant can be fatal. The therapeutic dose of foxglove is very close to the lethal dose. Foxglove should therefore not be used.

An overdose of foxglove interferes with the heart’s normal electrical rhythms; it can make the heart beat too slowly or cause extra heartbeats. An overdose of foxglove may also cause diarrhea, headache , loss of appetite, and vomiting . More serious and potentially deadly reactions to an overdose affect the heart and the central nervous system. Foxglove can disrupt the heart’s rhythm, including life-threatening ventricular tachycardia, or atrial tachycardia with atrioventricular block. In the central nervous system, foxglove can cause confusion, depression , drowsiness, hallucinations, psychoses, and visual disturbances.

Poisoning from foxglove occasionally occurs from the misuse of such herbal preparations as dried foxglove leaves used in a tea, or from overdoses of prescribed digitalis. It can also occur when foxglove is confused with comfrey , a plant used for tea that belongs to the borage family. The two herbs look very much alike.

Side effects

Some patients who take pharmaceutical preparations of digitalis may experience such side effects as too much muscle tone in the stomach and intestines, diarrhea, headache, loss of appetite, and vomiting. These side effects are the same as some symptoms of a foxglove overdose. Digitalis preparations can have toxic side effects due to overdose or other conditions. The most serious are arrhythmias, abnormal heart rhythms that can be life-threatening.

Interactions

The use of digitalis can increase the toxicity of other cardioactive drugs. Hypersensitivity to digitalis, dehydration, or the use of diuretics that cause people to lose fluids and salts may increase the risk of side effects from digoxin. The risk of cardiac arrhythmias is increased when people taking digitalis also take amphetamines or diet pills; medicine for asthma or other breathing problems; or medicine for colds, sinus problems, hay fever , or other allergies . Taking any of these drugs with digitalis also affects how much digitalis is in the body and how effective it will be.

Resources

BOOKS

PDR for Herbal Medicines. Montvale, NJ: Medical Economics Company, 1998.

PERIODICALS

Dickson, C. “Mountain Healing: Medicinal Plants of the Southern Appalachians.” Mother Earth News 173 (1999): 18.

Goldman, Peter. “Herbal Medicines Today and the Roots of Modern Pharmacology.” Annals of Internal Medicine 135 (October 16, 2001): 594–600.

OTHER

Lori De Milto

Rebecca J. Frey, PhD

Click to enlarge

The vibrancy of foxgloves belies their poisonous nature – ingesting even a small amount of the plant can cause unpleasant effects, and in some cases death. However, the same compounds that make it poisonous can also have medicinal uses. This graphic takes a look at them in detail.

The mantra ‘the dose makes the poison’ is oft-repeated in the field of toxicology; the foxglove perhaps provides one of the best examples of how true this is. The compounds in foxglove that lend it both its toxicity and medicinal use are called cardiac glycosides. A glycoside is a molecule which contains a steroid portion bonded to a sugar portion. The glycosides in foxgloves are found in higher concentrations in the leaves, but they’re still found in all other parts of the plant as well.

Ingestion of a small amount of parts of a foxglove can cause symptoms including nausea, vomiting, and diarrhoea. Though it may seem like an unlikely turn of events, the leaves of foxgloves can easily be confused with other edible plants – there’s a case of a man mistaking the leaves for that of another plant, and brewing a herbal tea from them. Larger amounts can result in death; although cases of this are rare, they have been documented.

Despite its toxicity, foxglove has actually been used in medicine for a number of centuries. Back then, it was used as a treatment for ‘dropsy’, what we now recognise as edema, an excess of fluid collecting in the tissues of various parts of the body. We now also know that this condition is often a side-effect of heart problems.

The use of foxglove for treating dropsy was trialled by an English doctor, William Withering. In the course of recording and eventually publishing his findings he found that foxglove extract was an effective method for treating dropsy and heart failure – though he also discovered it could have unpleasant effects if given in too high a dose. One of the more curious of these is a yellowing of the vision.

The foxglove extract, the key constituents of which are the cardiac glycosides digoxin and digitoxin, is known as digitalis after the Latin name for the plant. After Withering’s work, it became a common treatment for heart issues, including heart failure. Unusually for a drug that has persisted from antiquity to the present day, digoxin is still extracted from foxgloves, as it’s difficult for chemists to synthesise it in a cost-effective and efficient manner.

So how does digoxin exert its beneficial effects, and why is the line between its ability to heal and harm so fine? To answer this, we need more insight into how it affects the body. Though its exact mechanism of action is still unclear, it’s thought that it affects the sodium-potassium ion pumps in heart cells. These usually remove sodium ions from the cells. Digoxin stops sodium being removed from the cells, which has a knock on effect of causing the concentration of calcium ions in the cells to rise. This, in turn, interferes with the electrical signals that keep the heart beating, causing its pumping to become more forceful but slower.

This ability to interfere with and slow the heart rate makes digoxin useful for treating heart arrhythmias. It can still be used to treat heart failure, though its use for this has declined with the advent of other drugs. Its therapeutic range (the range in which it exerts beneficial medicinal effects) is very close to its toxic level – the point at which unpleasant effects start to be seen. In excess, it slows the heart rate so much that the brain becomes starved of oxygen; the body’s reflex response is to try and increase the heart rate, and this eventually results in a heart attack.

Finally, there are, of course, plenty of cases of people using foxglove and digitalis for more nefarious means. ‘Nature’s Poisons’ cites the case of a German doctor who murdered his girlfriend by administering the poison to his girlfriend rectally (!). Charles Cullen, New Jersey’s most prolific serial killer, also used digoxin to kill a number of his victims.

(It goes without saying, but do be wary of foxgloves, particularly if you’re into foraging. You need to ingest very little to experience toxic effects; if you notice symptoms, or think you or someone you know might have accidentally ingested some part of a foxglove, seek medical attention immediately.)

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References & Further Reading

  • Digoxin – E Stoye, Chemistry World
  • How to treat a broken heart, or poison your lover, with foxglove – J Brower, Nature’s Poisons
  • Digoxin – C Hogue, Chemical & Engineering News
  • Digoxin level – Medscape

How to prune and coppice foxglove tree

Paulownias – including P. tomentosa, P. fortunei and P. kawakamii – are fast growers that can reach up to 26m if left unpruned. They are impressive, beautiful trees with scented flowers in late spring, and in their native China they are prized for their wood. In western gardens, they are often coppiced to encourage the giant leaves that go with the post-pruning growth spurt.

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Planting Paulownia makes an exotic impact in a border, as a backdrop to delicate summer perennials or combined with other bold foliage plants for a dramatic effect.

Cutting While coppicing is generally best when plants are dormant, paulownias can be left until late in the spring – even May, after flowering. If you plan to coppice a mature tree, check it doesn’t have a tree preservation order, and ask an approved arboriculturist to do the initial pruning.

Tackle the pruning in stages, first removing outer branches with a small pruning saw to get access to the main stems. Cut larger stems using a jump cut to remove cleanly. A jump cut is actually three cuts. With the first two – upwards halfway from beneath, then downwards – remove the bulk of the stem, except for a short stub; the third cut removes this remaining stub.

Work your way down to the base of the plant, leaving a clean, smooth stool no more than 10cm above the ground. Mulch straight after coppicing and use a liquid foliar feed through the first growing season. By season’s end it will have produced a lush set of new leaves. The coppiced Paulownia grows as broad as it is tall, so allow 3-4m for expansion after the first cutting. Read our piece on why you should coppice.

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Spring: after flowering

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Before cutting, this Paulownia kawakamii is 3m wide and 4m high. Previous coppicing has increased the size of the leaves, encouraging the branches to grow outwards, in search of light.

The cutback

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The final stage of coppicing looks brutal, but it’s vital to leave a clean, smooth surface. Damaged wood makes it easier for disease and rot to creep into the stool.

Summer: outsized foliage

© Andrew Montgomery
After one season, the new growth is abundant. Individual leaves are huge, some as much as 24cm in diameter.

How to grow foxgloves

These foxgloves produce substantial rosettes of leaves, but no flowers in their first year. In their productive second year you can prolong flowering by cutting down the first tall spires as soon as the flowers have faded, only letting the subsequent “secondaries” produce and then drop their zillion seeds, a tiny proportion of which will make it to maturity. Most plants give up and die after flowering, but, surprisingly, others may produce new leaves in late summer, survive the winter and do a “third term”– these can have their tatty old foliage cut away, be firmed into the ground and fed to improve their general vigour.

Diseases

Rust? Mildew? Leafhopper-mottled leaves? Foxgloves are plants of woodland edges, but are more likely to become diseased and pest-ridden – and less likely to thrive – if grown in very dry shade. Unsightly leaves can be nipped off – but in my experience foxgloves eventually end their days looking shabby anyway, particularly those that do that extra lap.

Growing from seed

Are they best left to their own devices to self-seed, or should you sow them in seed trays, potting them on and planting them out as small plants as you would other biennials? If you acquire seed of individual colours it is a good idea to raise them in seed trays in spring, which gives you complete colour control. Chiltern Seeds has, among others, seeds of white and apricot varieties (01229 584549). However, I most often just shake the seed from existing plants around in spots where they will germinate when conditions are favourable, thinning out and moving individuals or groups of seedlings when big enough to handle, picking out white ones and placing them here and there to good effect, but letting the rest just happen where they will. Obviously to get a colony of foxgloves established from nursery-bought one-year-old plants, which is how most people start out, you will have to buy new plants for two years running to get the whole biennial merry-go-round going.

Buy foxgloves at the Telegraph Garden Shop

Foxglove Plants – Tips For Growing Foxgloves

Tall and stately foxglove plants (Digitalis purpurea) have long been included in garden areas where vertical interest and lovely flowers are desired. Foxglove flowers grow on stems which may reach 6 feet in height, depending on variety.

Foxglove flowers are clusters of tubular shaped blooms in colors of white, lavender, yellow, pink, red, and purple. Growing foxgloves thrive in full sun to partial shade to full shade, depending on the summer heat. They are hardy in gardening zones 4-10 and in the hottest areas prefer more midday and afternoon shade for optimum performance. The hotter the summers, the more shade the plant needs.

How to Grow Foxgloves

Foxglove plants grow best in rich, well draining soil. Caring for foxglove plants will include keeping the soil moist. As a biennial or short lived perennial, the gardener can encourage re-growth of foxglove flowers by not allowing the soil to dry out or to get too soggy.

Foxglove flowers may be grown from seed, producing blossoms in the second year. If flower heads are not removed, foxglove plants reseed themselves abundantly. Using them as cut flowers can decrease reseeding.

If flowers are allowed to drop seeds, thin the seedlings next year to about 18 inches apart, allowing growing foxgloves room to develop. If you want additional foxglove plants next year, leave the last flowers of the season to dry on the stalk and drop seeds for new growth.

The foxglove plant is grown commercially for distillation of the heart medication Digitalis. Caring for the foxglove plant should include keeping children and pets away, as all parts can be toxic when consumed. This may explain why deer and rabbits leave them alone. Hummingbirds are attracted by their nectar.

Varieties of Foxglove Flowers

Rusty foxgloves are the tallest variety of this specimen and may reach 6 feet, sometimes requiring staking. Foxy Hybrids foxglove reaches just 2 to 3 feet and may be an option for those growing foxgloves in small gardens. Sizes in between the two come from planting the common foxglove, which reaches 4 to 5 feet and hybrid types.

Now that you’ve learned how to grow foxglove flowers, include them in a safe, background area of the flower bed or garden to add the vertical beauty of foxglove blooms.

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