Jekkapedia: St John's Wort
St John's Wort

Hypericum perforatum

Clusiaceae


Hypericum perforatum, St John's Wort

Family: Clusiaceae
Genus: Clusiaceae

Lightly scented yellow flowers with tiny black gland dots. Small stalkless, oval, green leaves covered with tiny translucent resin glads that look like small spots. Important medicinal herb.

    Characteristics:
    Hardiness: H6 (-15 to -20C)
    Type: Semi Evergreen Perennial
    Height: 30-90cm
    Spread: 30cm

    St John's Wort can be seen at the herb farm in Jekka's Herbetum and is available to buy as both herb plants and online as herb seeds.

    Aspect: Sun, Partial Shade
    Soil type: Chalk, Clay, Sand, Loam
    pH: Universal pH
    Habit: Upright
    Flowering colour: Yellow
    Flowering time: Summer
    Uses: Medicinal (Read Jekka's Guide to Medicinal Herbs for more information)
    Attracts pollinators: Yes (Read Jekka's Guide to Pollinators for more information)
    Container suitability: Yes
    UK native: Yes
    Caution: Can occasionally make skin sensitive to light when taken medicinally. Poisonous to liverstock.
    Grown from seed:

    Indoor Sowing: In late spring, into prepared plug trays or pots, do not cover. Put in a cold frame.
    Outdoor Sowing: In early summer, into a well-drained soil with a sunny situation. Thin to 20cm apart.


    Propagation: Division
    Maintenance: (Read Jekka's Blogs on Early Spring, Late Spring and Autumn maintenance)
    Harvest: N/A

    St. Johns Wort is probably best known for its use in mild to moderate depression. However, it has other helpful attributes. Traditionally it has been used by herbalists to ease nerve conditions such as neuralgia, sciatica, cold sores and anxiety, particularly that associated with the menopause. Infusing the flowers in oil creates a deep red coloured oil that is used for its vulnery (healing) qualities, for example in wounds, bruises and shingles. It has a long history of use and was named ‘Hypericum’ by the 1st century Greek physician, Dioscorides. The name translates as ‘over an apparition’, a reference to its presumed ability to enable exorcism.

    Caution: St Johns Wort should be avoided when taking certain pharmaceutical medicines. These include anti-coagulants, calcium channel blockers, chemotherapy, digoxin, finasteride, HIV medication and immunosuppressants. It may also be wise to avoid taking this herb alongside oral contraceptives as it may increase the body’s metabolism of the drug making its contraceptive action less effective, but the clinical evidence to support this is contradictory. This herb can also cause photosensitivity so should be avoided by anyone with this tendency or who may be taking photo-sensitising medication.
    Please note: The information provided here is for educational interest only and is not intended to be used to diagnose or treat significant health problems. Any serious or long-term health concerns should always be discussed with a healthcare professional.

    See our blog for more information about the National Institute of Medicinal Herbalists

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    For information on growing herbs from seeds please see Jekka's blogs on sowing seeds, sowing your winter culinary herbs or how to grow vegetables.

    Jekka's "How to Grow Herbs" videos, includes Jekka's video on how to sow seeds  for an informative step-by-step guide to seed sowing.

    If you require pots or compost, see Jekka's Herb Kits that includes Jekka's Seed Sowing Kit. This kit contains all you need to sow a collection of herb seeds.

    For more information on growing herbs plants please see Jekkapedia, Jekka's blog or our FAQs page.

    Happy Herbs!

    At Jekka’s we sell herbs in 1 Ltr and 2 Ltr pots. These are established and hardy herb plants that are grown following organic principals and to survive the UK climate. Please read Jekka's blog that contains her top steps to growing on your herbs.

    There is also ‘Jekka’s Seasonal Tips’ series that covers growing and maintaining herbs in early spring, late spring, summer and autumn & winter. Together they form Jekka’s guide on how to grow herbs.

    If you require pots or compost, we have developed Jekka's Herb Kits, which includes Jekka's "Grow On" Kit. These kits contain all you need to grow on your herbs.

    If you think your herbs need a little more attention we always recommend an environmentally friendly solution, and these are Jekka's top three:

    • Maxicrop liquid seaweed: 'Feed on Fridays' as Jekka always says for all round good plant health.
    • SB Invigorator: a safe and effective insecticide and fungicide to help control a wide range of pest species
    • Epsom salts: the horticultural equivalent of what you put in your bath to top up magnesium and stop orange leaves.

    For more information on growing herbs plants please see Jekkapedia, Jekka's blog or our FAQs page.

    Happy Herbs!

    One of our three core roots is that we are Environmentally Conscious and for the past 30 years all the herbs grown at Jekka’s have been raised following sustainable, environmentally friendly and organic approaches resulting in a remarkable biodiversity at the herb farm.

    Our herb seeds are also untreated and can be used to grow organic herb plants.

    You can read more about our sustainability approach to growing herbs in one of Jekka's Blogs or in Jekka's Guide to Climate Change.



    Guide to Jekkapedia

    Everything you need to know

    Our herb plants are available for purchase direct from the farm at our Open days or by Collection, by prior arrangement, on a Wednesday between 10am and 3pm. However, if this is not convenient, please email us at sales@jekkasherbfarm.com and we will try and accommodate your request.

    The Botanical Name is known throughout the world. It includes the genus and the species plus in some cases the cultivar. For example Agastache is the genus, rugosa is the species and Agastache rugosa ‘Golden Jubilee’ includes the cultivar.

    The Common Name is the name by which the herb is commonly known, for example thyme, sage etc. But please be aware that common names are often colloquial and relevant to the area in which you find them.

    The Plant family is the group of plants which is more comprehensive than the genus.

    - Annual a plant that lives for just one season.
    - Biennial a plant that produces leaves in the first season and flowers in the second, then dies.
    - Climber/Vine a plant that cannot grow without the support of other plants or structures.
    - Deciduous a plant that drops it leaves in winter.
    - Evergreen a plant that has leaves all winter.
    - Herbaceous a plant that dies back into the ground in winter, becoming dormant, before reappearing in the spring.
    - Monocarpic a plant that dies once it flowers; it can live for a number of years before flowering.
    - Perennial a plant that lives for a number of seasons, most flower annually once established.
    - Partial Evergreen a plant that holds some leaves throughout the winter.
    - Shrub a woody stemmed plant that usually freely branches from the base.
    - Sub-shrub a small, short, woody shrub, especially one that is woody only at the base.
    - Sub-tropical a plant that can only survive in a warm, damp climate that does not drop below 10°C at night.
    - Tree a woody plant that usually has a single stem.
    - Tropical a plant that can only survive in a warm, damp climate that does not drop below 15°C at night.

    Recommended planting position in the garden or where to place a pot, e.g. sun, partial shade etc.

    Plants grow in many shapes and forms:

    - Upright: a plant that is very straight.
    - Clump: a plant that grows in a neat compact shape.
    - Bulb: a plant that dies back into a bulb.
    - Mat forming: a plant that grows low to the ground and makes a neat mat.
    - Creeping: a plant that grows along the ground and produces roots at intervals.
    - Bushy: a plant that, in the main, tends to be a shrub which makes a bush-like shape.
    - Arching: a plant that grows upright then the growth arches, ideal for growing over a wall or in a container.
    - Prostrate: a plant that lies flat on the ground.

    This indicates the average spread and height that the plant will achieve in its life. It helps to know this when positioning plants in the garden. Bear in mind, that height and spread vary in definition according to the following plant types:


    - Annual: this is the spread to which it will grow, and the height when in flower during the year.
    - Biennial: this is the spread in the first year and the height of the flower in the second year.
    - Herbaceous perennial and perennial: this is the spread the plant will achieve after a number of years once mature and the height when in flower.
    - Shrub/evergreen tree: this is the average spread and final height after a number of years of growth.

    All ratings refer to UK growing conditions and are based on the Royal Horticultural Society hardiness rating. The minimum temperature range, in degrees centigrade, are shown in the brackets below:

    - H1a (15°C minimum): Under glass all year.
    - H1b (10°C to 15°C): Can be grown outside in summer.
    - H1c (5°C to 10°C): Can be grown outside in summer.
    - H2 (1°C to 5°C): Tolerant of low temperatures but will not survive being frozen.
    - H3 (-5°C to 1°C): Hardy in coastal and relatively mild, sheltered parts of the UK.
    - H4 (-10°C to -5°C): Hardy through most of the UK.
    - H5 (-15°C to -10°C): Hardy in most places throughout the UK, even in severe winters.
    - H6 (-20°C to -15°C): Hardy in all of the UK and northern Europe.
    - H7 (-20°C and below): Hardy in the severest European continental climates.

    The soil is the engine of your garden, so it is important to know its condition before you start planting. Good plant growth is not only dependent on how much you feed the soil but it is also dependent on the structure of the soil. Soil can vary from acidic (pH 3.5) Sphagnum moss peat to alkaline (pH 8.5) Fine loam. Most herbs will tolerate a range of between 6.5 and 7.5 pH which is fairly neutral. There are always exceptions, for instance Rumex scutatus, Sorrel, will tolerate acid soils.

    The pH of the soil refers to its acidity or alkalinity. It is a vital factor in the plant’s ability to obtain, via its root system, all types of plant foods and essential chemicals. For example, an alkaline soil can produce stunted plants with yellowing leaves. This is because the minerals, especially iron, have become locked up in the soil. At a neutral pH of 7, most of the essential chemicals and plant foods become available to the plant so producing healthy plants.

    The following 4 basic soil types are the most suitable for growing herbs:

    - Clay 6.5 pH: This soil is composed of tiny particles that, when wet, stick together making the soil heavy and difficult for the roots to penetrate and in summer, when dry, sets rock hard. Even though it can be rich in plant nutrients, because of its characteristics it is improved by working in extra well rotted leaf mould or compost. This will improve the structure and allow young plants to become more easily established.
    - Chalk 8.5 pH: This soil is light with lumps of flint or chalk, well drained and often shallow. It has a high pH making it very alkaline. It is possible to increase the nutrient content by adding loads of compost but it is difficult to lower the pH. A large number of herbs will tolerate chalk. However, considering the characteristics of this soil, to give it depth and help it retain moisture it may be easier to grow the herbs in a raised bed.
    - Loam 5.5–8.5 pH: This is often considered the ultimate garden soil in which most herbs will grow. There are various types of loam depending on the content of clay or sand. A sandy loam is the best soil for growing the largest range of herbs as it is rarely waterlogged in winter, is dry in summer and it is naturally high in nutrients.
    - Sand 4.5 pH: This soil feels rough and gritty when handled. It is very free draining, which means that the plant’s nutrients are quickly washed away. A plus point to this soil is that it is quick to warm up in the spring so sowing and planting can be started earlier than in clay soils. To help it retain moisture it needs to be fed in winter with leaf mould to retain moisture and with well-rotted manure for an extra source of nutrients.

    Checking the pH of the soil
    To test your soil buy a soil testing kit from any good garden centre or store. The majority of amateur soil testing kits are very simple and rely on colour rather than a numerical scale. Acid soils turn a solution yellow- orange, neutral turn it green and alkaline turn a dark green.