Starting Your Herb Garden - Part 2

Soil

Just as humans can only extract their goodness from the foods that they put into their bodies, so do plants obtain the nutrients that they need form the soil that they live in.

Plants grown in soil that is lacking in zinc and selenium, as the soils can tend to be in Australia and New Zealand, will only produce plants low in those two minerals. Hence why many Australians are also lacking in these two minerals.

So what would be an ideal soil type?

Is there an ideal soil type for growing herbs?

When it comes to growing herbs I would be more prone to picking the herbs to suit my soil type and location, rather than changing the environment to suit the plants. It is possible to change your soil type, though this takes time and the time frame here can be years of working the soil. 

The Best Soil 

An ideal soil type would be one that is light enough to make the entire cultivation process quite easy, as well as being able to retain enough moisture and this is dependant on the organic matter content of the soil. A fertile soil is not always essential, moderate fertility levels are often recommended especially with some plants such as calendula. Calendula will actually produce less prolifically if in a highly fertile soil.

There are many things that can be done to improve the soil. Most Australian soils that we have come across tend to have problems with impaction and poor organic matter content. These can be quite easily rectified.

Earthworms are a good indication of a healthy and happy soil. One reason why they are so beneficial is because they help to aerate the soil. People can often forget that an essential component of a healthy soil is air spaces. Plants need air under the ground as well as on top and this is one major issue of soil impaction. As the worms burrow around they help create air spaces as well as helping to improve drainage. Worms will not live in a soil that has been sprayed with a wide range of chemicals, herbicides and fungicides. They, like frogs, like a clean environment.

Soil impaction is a result of mono-cropping, using heavy machinery and having excessive stock, squashing the air pockets in the soil. We tend to recommend deep ripping the soil once and then avoiding heavy machinery or over stocking the soil.

Having more organic matter in the soil will reduce the effects of soil impaction, as well as helping to buffer an over acid soil. Whilst on the subject of pH, a pH of 5.5 to 6.5 is a good average pH to be growing herbs. A select few herbs might need a higher pH, though in general a pH above 7 can cause a major problem with some species.

Poorer soils can be built up, though not over night. Adding composted material and providing the essential foods for the soil is one great way to build up soil quality. It is often forgotten that it is the microbial function of the soil that gives life to the soil. The type of microbes and organisms that are present in your soil is determined by the environment that you have established for them. It is the landowner that is solely responsible for your soil and ultimately your crop.

Actinomycetes, mycorrhizae, algae, aspergillus oryzea and Aspergillus niger are all beneficial micro-organisms that are part of the soil and plant connection and interaction. When spraying herbicides and fungicides on the soil, you are actually killing these microbes and fungi and in turn the activity of the soil. Algae are one of the most important micro-organisms in the soil. It is these algae that produce sugars which feed the all important bacteria that protect and feed the crops we grow.

So when looking for good soils, aim for a soil that is easy to dig, it holds good form when squeezed together, it often has a darkish appearance, with a sweet smell, as well as being able to hold enough moisture to prevent drying out.

Pollution and Contamination

If you are choosing a new site to start growing herbs and will be starting from fresh, it would be preferable to not to be using contaminated or polluted lands.

Are you aware of what the farming practises of your block were prior to you being there?

Old industrial areas and places near road will carry pollutants and possible toxic metal residues. These will quite easily be picked up in your soil and then will be transferred to your plants. Cities are prone to smog and industrial pollutants. Roadside growing can be high in lead fallout, which can take years or even generation to go away.

Conventional farming areas that commonly use heavy amounts of pesticides are crops such as tobacco, apples, cotton and potatoes. These crops are likely to have high residues of lead, DDT and Dieldrin.

Other places where contamination can be an issue, is in water sources. A friend in a neighbouring town, had their tap water tested for their swimming pool and it was discovered that no further chlorine was required, meanwhile you might choose to water you plants with this water (Let alone us drink it). High fluorine and chlorine levels will evaporate out of the water over time, though you might need to have at least one settling tank for this purpose.

Water can also have contamination from upstream activities. Sewerage effluent, industrial wastes, nitrates, pesticide residues, heavy metal toxicity and mining or milling effluent could all be happening upstream.

Considerations About Growing Organic Herbs  Commercially 

Growers of medicinal herbs need to achieve a balance between producing the herbs that meet the demands of their target market and achieving efficient production, harvesting, storage and processing performance

• When investigating the agronomic potential of different herb crops, growers must be prepared to research the different production, harvesting and drying practices that are required by each herb crop. In particular, producers must identify production limitations such as over-wintering, heat and moisture requirements, as well as the length of growing season for each crop being considered.
• The critical production issues for herb and spice crops are crop selection, site selection, adaptability, seedbed preparation, seeding, fertilization, weed control, harvesting, storage and processing.
• Herbs can be classified as annuals, perennials or biennials. Producers should be familiar with the winter hardiness and adaptability of the different herb varieties. Perennials and biennials need to withstand winter conditions and may require management practices such as autumn mulching.
• Organic production of medicinal herbs will increase the acceptance of herbs by buyers and may bring higher prices. For many medicinal herbs, certified organic production may be the only way to gain access to a market. Organic herbs are generally valued at significantly higher prices than those for non-organic herbs.
• Growers need to determine how different herb crops respond to sunlight. This is because sunlight and soil health will influence the production of the constituents that create, these provide the health benefit.
• Growers have to determine how tolerant the various herb crops they select are to soil moisture. Many herbs require well-drained soils since their roots can weaken and die in excessively moist (and cool) soils.
• A sheltered growing area provides protection from hot winds that can stop the growing process in some herbs.
• Most herbs have small seeds and require a firm seedbed to ensure soil contact and to increase germination. Seeding depth ranges from 0.3-1.19 cm, depending on soil moisture and seed size.
• Since few herbicides are available for herbs and herbs are often grown for organic markets, weed control may rely on manual and mechanical cultivation. 
• Growers need to carefully consider the time/labour commitment in growing medicinal herbs.
• Irrigation will benefit herb crops, in particular, irrigation may allow growers to push their crops for earlier harvest and in some cases achieve two crops per year.

If you would like to learn more about growing or using herbs, check out my online courses.   http://www.chi-institute.com.au/online-courses/herbal-medicines