Miracle herbs that can heal

New research has found that lemon balm, a common garden herb, can boost memory by countering the effects of stress on the body. The findings add to mounting scientific evidence that many common garden plants - and weeds - could be our best treatments for colds, allergies, insomnia and even heart disease. Here, we reveal your garden's secret medicines.

Lemon balm

Herbalists have traditionally used lemon balm as a stress antidote. Researchers have found that stress harms memory, and it is thought that lemon balm's calming effect led to improved cognitive function and memory in trials at Northumbria University. To benefit from this effect, pick a few sprigs and steep in hot water for several minutes before drinking. Other studies have found that dabbing lemon balm essential oil onto cold sores early on can deactivate the herpes virus which triggers them. This gets rid of symptoms such as tingling in minutes and speeds healing times from several weeks to around four days.

Chickweed

An anti-inflammatory and anti-itch cream can be made from chickweed, a common garden weed. Studies have found it can alleviate irritation in allergic rashes and eczema. Macerate a sample and soak in olive oil for a week. Strain and mix into a standard base cream, available from most chemists.

Thyme

Traditionally used as an expectorant in colds and flu, trials have confirmed that thyme syrup is as effective as medical expectorants such as Bromhexine. Thyme essential oil combined with rosemary and mixed into a lotion can also help hair regrowth in alopecia and be used to treat dandruff. For an expectorant, infuse a teaspoon of thyme in hot water for five minutes and drink. An anti-dandruff rinse can be made by boiling a tablespoon of rosemary and thyme in a pint of water for 10 minutes. Leave to cool then apply.

Elderflower

Elderflower and elderberries have been used to combat colds and flu for centuries. Recent studies have identified potent anti-viral and bacteriocidal compounds in the flowers, leaves and berries. The berries also help ease congestion and sinusitis by removing catarrh. Elderflower tea and even elderberry crumble has therapeutic effects.

Red clover

Red clover flowers contain high levels of phytoestrogens, which mimic the body's natural oestrogen. Early trials have found that flowers, drunk as tea during the menopause, will help even out hormonal fluctuations, reducing hot flushes, mood swings and vaginal dryness. They may also have a protective effect against breast cancer. Pick the flowers in June and July; dry them for use later in the year.

Sage

The identification of anti-microbial agents in the common herb, sage, explain why it is so effective at calming sore throats - steeped in hot water, cooled and used as a gargle, it can even prevent colds if used early enough. Although it's not known how it works, some studies have found that when drunk as tea three times a day, sage can reduce the severity and frequency of menopausal hot flushes.

Hawthorn

Hawthorn berries and leaves can increase oxygen supply to the heart, boost the force of contraction, protect the heart from oxidative damage and reduce blood pressure. Numerous studies worldwide have confirmed that, in many cases, hawthorn extract works as well as conventional heart medications such as captopril, but without side effects. Hawthorn can also boost athletic performance. For a DIY heart tonic, collect hawthorn berries, soak in brandy for three weeks and strain. Take a tablespoon of this liquid three times a day. Heart patients should seek medical supervision.

St John's Wort

Used as a medicine by early Christians, St John's Wort contains hypericin, an agent that raises levels of the feel-good chemical, serotonin, in the brain. It is the most commonly prescribed herbal anti-depressant. As it is also a potent anti-viral agent, clinical trials have found that St John's Wort can help treat chickenpox, glandular fever, viral hepatitis and flu. Flowering in June, it can be bought from most gardening shops - its leaves and flower can be infused into a tea.

Nettle

Nettle soup or tea is a powerful antiallergy remedy - taken in the buildup to hayfever season, it can reduce and even prevent symptoms. Studies have found it works by blocking chemicals called cytokines that trigger allergic symptoms. The leaves can also help to alleviate arthritis. Nettle root blocks substances that cause prostate enlargement in older men and has been found to be as effective as conventional medication with fewer side-effects.

Garlic

Studies in America and Britain have confirmed that garlic is such a powerful anti-bacterial, fungicidal and anti-viral agent, it can effectively stave of colds and flu if taken at the first signs of infection. However, since one of its key components, allicin, degrades on exposure to air, a clove needs to be eaten raw for full effect. Garlic also reduces cholesterol and blood pressure -just one clove can cut cholesterol levels by nine per cent.

Peppermint

Peppermint can help asthmatics breathe - trials have found that inhaled as an infusion, menthol oil from the leaves reduces spasm in the bronchial muscles of the lungs. Research has confirmed that peppermint tea, a traditional " digestive" drink, reduces irritable bowel syndrome symptoms and acid stomach.