COMPANION GARDENING

Some notes by Kate Nash, U3A Gardening Group Member

September 2013

Positioning plants together that are reputed to have a beneficial effect on neighbouring plants by discouraging pests and diseases or improving growth.

There are many companion plants that are very well known and we probably all use these partnerships already.

French marigolds produce a pesticidal chemical from their roots, so strong it lasts years after they are gone. Mexican marigolds do the same, but are so strong they will inhibit the growth of some more tender herbs. Certain Varieties of marigolds can help manage eelworms when planted the year before. Tagetes has also been found effective against perennial weeds such as Celandine, Ground Elder Ground Ivy and Couch Grass.

Foxgloves and sunflowers in the flower beds encourage beneficial insects and putt particular vegetables together like carrots and onions to deter pests such as carrot fly.

However, there are many, many ways of companion gardening and hopefully there may be some you hear later that might influence your planting next year.

Some of the less well known ones are:

· Camomile plants have a reputation for improving the vigour of surrounding plants.

· Lovage, Borage and Geraniums are said to stimulate the growth of all plants, they are the magic recipe of Companion planting.

· Oregano provides ground cover and much-needed humidity for pepper plants if allowed to spread among them

· Lupin is a legume, hosting bacteria that fixes nitrogen in the soil, fertilizing it for neighbouring plants

· Penny Royal planted in between paving is said to keep ants away.

· Summer Savoury planted in rows next to Broad Beans provide protection from aphids

· All the strong smelling Allium plants are beneficial in detering pests . Chives have the same companion traits as all alliums (onions, garlic, shallots, leeks, etc.)said to prevent apple scab after 3 years planting at base of apple trees

· Plantings of Horseradish plant (recommended you plant in a pot) between rows of potatoes helps disease resistance of potatoes.

· The flowers of the parsnip plant left to seed will attract a variety of predatory insects to the garden, they are particularly helpful when left under fruit trees, the predators attacking codling moth and light brown apple moth. The root also contains Myristricin, which is toxic to fruit flies, house flies, red spider mite, pea aphids, a simple blender made extraction of three blended parsnips roots to one litre of water through a food processor (not one for preparing food) and left overnight, strained and use within a few days.

Green Manure

Green manure crops add nitrogen to the soil. Cheapest and most effective is to collect your own Broad Bean seed by allowing some pods from the Spring and Summer crop to ripen and then planting them in August/ September . The crop should be dug in well before the stems become hard and woody. Allow to wilt first then dig in to a depth of 15cm to allow organisms to have enough air and warmth.

Wood Ash contains potassium and trace elements. Apply in small amounts to compost heaps or spread around onion plants to deter 'cutworms' Bob Flowerdew recommends spreading it on onion foliage to prevent mildew.

Keep roses clean by underplanting with lavender, violas or hardy geraniums which prevent fungal spores being washed back on to the rose.

Orange slices hung up attract wasps and ants away from ripening fruit.

Yarrow may increase the essential oil production of some herbs. Also improves soil quality, use the leaves to enrich compost, or as mulch,

Some plants should not be grown in close proximity for example

Coriander will cross-pollinate easily with dill and ruin both plants.

Fennel is negatively Allelopathic to most garden plants, (it gives off biochemicals which could result in inhibiting growth, causing to bolt, or actually killing many plants). The only herb that is said to grow well with Fennel is Dill.

Beneficial weeds

Some “weeds” can accomplish a number of roles in the garden or yard, including fertilizing the soil, increasing moisture, acting as shelter or living mulch, repelling pests, attracting beneficial insects, or serving as food or other resources for human beings

· Clover hosts nitrogen-fixing bacteria in its roots, and therefore fertilizes the soil for neighbouring plants

· Wild Vetch fixes nitrogen, allow it to grow in a tomato garden only until time to plant, as ground cover. But can be left growing among brassica for additional nitrogen and microclimate.

· The dandelion tap root breaks up hardened soil and brings up nutrients from deep down, benefiting plants with weaker or shallower roots without competing with them. It also attracts honeybees and is used as a diuretic in herbal medicine (dandelion tea)

Liquid fertilizer from plants.

Nettle and comfrey can be used as a fertilizer. Put leaves to soak in water for a few weeks in a bucket with a lid in the shade and then use 1 parts liquid to at least 4 parts water.