Raising new plants

Basic plant breeding should be mastered by everyone interested in organic gardening. On account of being raised from hybrid stock, many of the commonly available fruit and vegetable varieties are too challenging for beginners to engage with. Alternatively, herbs are the easiest of plants to propagate using time established techniques which provide an excellent learning foundation. Herbs can be propagated by seed, cutting, or by division.  Once mastered, these techniques will provide the dedicated organic gardener with increased control over the quality and essential characteristics of their favourite herb varieties. It also encourages sharing of plants between friends, neighbours, and fellow gardening enthusiasts. Consider giving a beautiful living bouquet of organically grown herbs as a housewarming gift for a close friend. What about a flourishing lemon balm for a neighbour with the flu, or a juvenile aloe plant for relatives with active or accident prone children?

Raising herbs from collected seed can be a satisfying and cost effective means of stocking the organic garden. At present, there are minimal incentives for horticultural and biotechnology firms to develop new varieties of herb. As a consequence, the vast majority of herbs are genetically robust and widely regarded as excellent to obtain seed from. Before running to seed, ensure that candidate plants are in good health and exercise care to exclude sterile cross breeds and others which cannot reproduce true to type. For tiny seeds such as parsley, it is important to allow the heads to dry out without waiting until shedding commences. Remove seeding stalks and secure paper bags over each head before hanging these upside down, allowing the seeds to fall inside the bags with the assistance of gravity. For larger seeds, careful hand picking over a flat, covered surface is recommended. 

To prevent structural damage and disease, all seeds need to be thoroughly dried before storing. Professional dehumidifiers are available from nurseries and organic supply shops, although effective results can also be obtained from a laundry airing cupboard. Once dried, seeds can be packaged in carefully labelled envelopes, and sealed in a darkened, airtight container. The preferred storage environment must be dry, dark, and cool, and some gardeners even like to include sachets of silica gel crystals to absorb any additional moisture which might otherwise decrease storage longevity. When these steps are followed, there is no reason why seeds should not remain viable for several years.

There are several delicately rooted herbs which must be sown directly to soil since they cannot easily tolerate transplanting. The main examples are caraway, anise, and parsley although others including nettle, nasturtium, dill, chervil, and borage will benefit from sowing directly to soil. The seed bed needs to be prepared several weeks prior to sowing in early spring. Herbs like parsley require a reasonable soil temperature to germinate properly so it is probably better to delay sowing for a week or two if garden conditions dictate. Rake over the soil to remove weeds, rocks, and other debris which can disrupt seedling emergence and growth.

Many organic growers like to cover their prepared beds with a sheet of clear perspex. This will increase midday soil temperatures and encourages rapid germination and growth of any weeds present in the soil. These can then be removed by hand prior to sowing the herb seed. In dry weather, it can be helpful to soak the herb seed in warm water for several days prior to planting.

Seeds should be planted in rows of trenches which have a depth of approximately twice the seed thickness. Remember, from an organic perspective, it is considered good practice to interplant herb varieties among vegetables and other plant species. This helps to control pest infestation and can also encourage mutually beneficial soil and nutrient utilisation. Use a soft spray to water the seeds twice a day until the new seedlings emerge. After several weeks the seedlings should be thinned out by cutting the stems of unwanted plants. An alternative to direct sowing is the use of plug trays or peat pots which enable seedlings to become established before transplanting them into the garden site with minimal root disturbance. 

Permanent seed trays or individual punnets allow organic growers to raise seedlings under controlled conditions. Indoor and glasshouse sowing will enable annual herbs to commence and become established earlier than external conditions might otherwise permit. Compared with open ground sowing, there is a lower risk of losing seedlings to poor weather, pest infestation, and disease. In some environments, the foraging activities of birds and native mammals can make it almost impossible for seedlings to survive in the open. Annual herbs should be sown to punnets around six to eight weeks before planting out while perennials typically require twice this preparation.

Punnets and planting trays can be purchased from most nurseries and organic suppliers however plastic yoghurt tubs and cardboard milk cartons can be recycled for this purpose. Ensure they are first sterilised with boiling water or disinfectant and that adequate drainage holes have been drilled into each base. Permanent seed trays can also be constructed in a suitably sunny and sheltered location. By using insulating and protective materials such as brick, shade cloth, and perspex, it should be possible to maintain a fairly constant temperature.

Leaf mulch makes an excellent foundation for an organic seedling medium. This should be mixed with equal parts of sandy soil and loam to facilitate drainage and aeration. As the seedlings mature the richness of the medium can be increased by including small quantities of liquid worm compost, seaweed, and garden compost. Sow small quantities of herb seed to a depth around twice their thickness. Carefully label each seed container with the herb variety and sowing date. After sowing, trays can be covered with sheets of safety glass or perspex. This will increase soil temperature and encourage an even distribution of moisture. Once the seedlings have emerged, these covers should be removed to discourage root and leaf fungi. Seedlings are thinned by chopping the stems of unwanted specimens. Once seedlings are forty millimetres high with four or more leaves, they can be transferred directly to the garden or into individual pots. The decision must be based on the natural resilience of each species combined with an evaluation of local conditions. Vulnerable seedlings require additional acclimatisation before planting out, and all seedlings must be protected against frost.

Many herbs can be propagated by separating and cultivating a chosen section of parent stock. The relevant techniques include root division, plant division, bulb separation, layering, and cutting propagation. Also known as reproduction by division, these methods create new plants with the genetic profile of the parent stock. This has the advantage of predictability, providing that the parent stock is organically certified, strong and healthy.

In many instances, this form of reproduction will be easier on the parent plant, since there is no requirement to produce seed. Fennel, elderberry, feverfew, ginger, horseradish, hyssop, lemongrass, rosemary, catmint, and lemon balm are herbs capable of producing rhizomes, or underground runners. When buds attached to these rhizomes begin to emerge in early spring or autumn, a knife or pair of secateurs can be used to remove a forty millimetre section, ensuring that the living bud is included. The root section can be temporarily stored in a glass of water by a windowsill or replanted immediately to a pot or different area of the garden.

Bergamot is an example of an herb with above ground runners. In a similar fashion to rhizomes, each runner with a viable bud can be separated from the parent and replanted to pots or open ground. Naturally spreading herbs like mint, sage, lavender, and thyme can be dug out then divided into multiples, each with their own foliage and root network. Chives and garlic are both propagated by bulb separation. Any healthy growth of chives can be divided into multiples so long as each one is supported by several of the rooting bulbs. Fresh garlic is often commenced in spring from the outer cloves of a dried bulb. Individual cloves must be planted two hundred millimetres apart, at a depth of thirty millimetres with the root end facing down.

Tarragon, rosemary, thyme, and sage, are all herbs which can be reproduced through layering. This involves selection of flexible stems from the parent stock and burying each stem approximately twenty millimetres deep without cutting or separation from the parent. After three or four weeks there should be some root development around the buried stems. These should be dug out after several months and replanted to pots or open ground.

Nearly every gardener has grown a plant from a cutting offered by a neighbour or friend. It is one of the easiest methods to apply in spring or autumn, particularly for resilient herbs like lavender, thyme, oregano, and bay. To increase the likelihood of success, cuttings should be taken as hundred millimetre stems of fresh green growth containing two or more pair of leaf nodes. The lower leaves are then removed and the stem is floated in a jar containing water and a small quantity of organic material such as liquid worm compost. Ensure that the stripped nodes lie beneath the liquid and the stem receives a reasonable amount of sunlight throughout the day. After a month or so, successful cuttings will exhibit root development around the stripped nodes. These cuttings should be removed from the liquid and stored in shade for several days before planting to pots or open ground. For individuals belonging to organic gardening clubs or horticultural societies, cuttings appropriated through fellow members will help to establish an impressive herb garden at minimal expense.