Good soil is always beneficial for herbs growing, regardless whether you plant them indoors or outdoors. The soil type is the main thing contributing the health of your herbs, and in fact, all plants. How does your herb make full use of the soil? To your herb, the soil is the source of all the chemical components which it uses to power its growth, biology, and reproduction.
what soil type for herbs growing? The main components of soil that are deemed important to grow herbs – nitrogen, phosphorus, moisture, PH level, and drainage, these elements are all determined by the nature of the soil used, and therefore, maintaining them all at optimum level is essential if you want to cultivate healthy herbs at all. Moreover, if you plant your herbs in containers, then you are solely responsible for almost all the needs of your herbs. Thankfully, most herbs do not have high requirements.
Most herbs like dry, alkaline soil with excellent drainage. Examples are lavender, anise, sage, and horehound. If the soil is kept too wet, some of these herbs that like it dry, may suffer from root rot. Most herbs cannot grow well in wet soil, preferring just a little moisture to semi-desert like conditions. The few that like moister soil include herbs like peppermint, chives, mint, and coriander. Adding a little compost to the soil can aid in helping the soil be more water retentive.
The ideal soil for herbs growing is one that isn’t too sandy or clayey. The particles of clay suspended in clay-rich soil will readily absorb water and retain it, while sandy soil which is rich in quartzite particles, have relatively large spacing in between the particles which on one hand provides for good air circulation and water flow, but need a certain amount of periodic enrichment, as on their own, they provide very little natural nutrients for the herbs.
The mineral content of soil is quite important for many herbs. Some herbs prefer more calcium rich soil, and for these, you could add more calcium in the form of lime or better still, crushed eggshells or shellfish shells (farm grit). Bear in mind that more calcium carbonate in the soil will increase the alkaline level of the soil, and what you want to achieve is only a slightly acidic or slightly alkaline environment, depending on the herbs you want to grow. Any more than that and the plants will develop problems like pale leaves and retarded growth.
How do you test the pH level of your soil? Just get distilled water (pH 7), and toss a spade full of soil into the water. The water needs to be of similar amount (volume wise) to the soil. After that you stick in a piece of pH paper strip (available from lab supply and aquarium shops), and compare it to the pH chart which these pH kits usually supply. If it’s below pH 7, the soil is acidic, but if it’s above pH 7, than the soil is alkaline.
Most culinary herbs are native to the Mediterranean region, which implies lots of sun, breezy air, and well drained, rocky soils. These soils are also quite shallow, and these Mediterranean herbs therefore do not root deeply. So try to recreate this environment if you’re growing Mediterranean herbs like coriander, thyme, and parsley. Do not plant them too deep, a general depth of 6-8 inches below the surface is more than adequate. You can also plant them in a raised bed, and wall in the bed with wooden planks. Containment is useful if you’re planting perennial herbs that propagate by runners, like mint.
What is Soil pH?
Let’s get all scientific for a moment and learn what pH is. In chemistry pH is a measure of how acidic or alkaline a solution is. Okay chemistry lesson over. Basically soil pH is a measure of how acidic or alkaline your soil is. Soil pH is measured on a scale of 1 to 14. If your soil has a pH value of less than 7 then you have acidic soil. On the other hand if your soil has a pH value of greater than 7 then you have alkaline soil. A pH value of 7 is neutral, meaning you have neither acidic or alkaline soil.
The Effect of Soil pH on Plants
Knowing the pH value of your soil before planting is very important as it has a direct influence on the health of the plant. Each plant has its own recommended soil pH value range. The reason for this is that soil pH effects the availability of nutrients within the soil and plants have different nutrient needs. For example the nutrient nitrogen, a very important plant nutrient, is readily available in soil when the pH value is above 5.5. Similarly the nutrient phosphorous is available when the pH value is between 6 and 7. If a plant is placed into the wrong kind of soil it will be lacking in nutrients that it needs which will promote disease. In general the best pH value range for soil is approximately 6 or 7 as this is the range in which most nutrients can be readily available.
Finding Out pH of Soil
A quick way to find out the pH of an area is to look to see if there are any house hydrangeas (Hydrangea macrophylla) already growing in the area. If so observe the colour of its flowers. A soil pH of 6 or below will produce blue flowers while a soil pH of 6.8 or higher will produce pink flowers.
Finding out the pH of soil is usually a trivial matter and the kits to do so should be available at most good garden centres. Usually a pH testing kit will include a small container / test tube, testing solution and a colour chart. A sample of soil is taken from your garden, placed into the container / test tube and a few drops of testing solution are added. The container is then shaken and left for a certain period of time. The colour of the sample in the container is then compared against the colour chart to determine the pH value of the soil. Note that if you want to determine the soil pH of an large area it may be a good idea to take soil samples from many different locations, combine the samples and then perform the test on the combined sample. There are also commercially available electronic PH testers available which one simply puts into the soil and they then give you a reading a lot simpler than messing around with test tubes.
How to Make Soil More Alkaline (Increase pH)
If your soil is acidic or slightly acidic you can take steps to make it more alkaline to accommodate the plants you want to put there. You can make your soil more alkaline (increase its pH value) by adding a form of lime. Lime is a compound of calcium or calcium and magnesium. It is usually applied in the form of ground agricultural limestone, burnt lime or hydrated lime (slaked lime). The smaller the limestone particles then the quicker your soil will become more alkaline. For this reason hydrated lime will offer the quickest performance because it is slightly soluble in water so it can permeate the soil quicker and reduce acidity faster.
Increasing the pH of your soil is not an overnight process and it is best to allow 2-3 months to allow the lime to neutralize the acidity of the soil acidity.
How to Make Soil More Acidic (Decrease pH)
Some ornamental plants and fruit plants like blueberries require an acidic soil. To make your soil more acidic (decrease its pH value) you can use either aluminium sulphate or sulphur. Aluminium sulphate is the quickest acting as it will increase the acidity as soon as it dissolves into the soil. The downsides are though that its effects can be short term and it is possible to over-apply it.
The more recommended but slower way to increase your soil pH is to use sulphur. Sulphur converts to sulphuric acid with the help of bacteria in the soil but this takes time depending on factors like the presence of bacteria, texture of the soil and moisture levels. This could take months if conditions are not ideal.
Most plants, herbs included naturally prefer a slightly acid soil. But here is a list of plants that thrive in acidic soil conditions.
Herbs that do well in acidic soils
Aconite, alfalfa, alkanet, annatto, angelica, avens, lemon balm, basils, bay laurel, sugar beet, belladonna, bilberry, bloodroot, boldo, borage, broom, burdock, butterfly bee, calendula, castor bean, celery, chicory, garlic chives, sweet cicely, citronella grass, clivers, red clover, codonopsis, black cohosh, coltsfoot, cumin, dandelion, elecampane, purple foxglove, garlic, ginseng, guava, henbane, henna, hops, horehound, indigo, lambs quarters, lemon grass, luffa, common marjoram, apple mint, English mint, menthol mint, pineapple mint, spearmint,(most of the rest of the mints prefer it a bit less acid), white mustard, stinging nettle, Welsh onion, compact oregano, gold crisp and golden oregano, showy oregano, papaya, paprika, passion fruit, patchouli, Chili peppers(of the genus Capsicum annum), pokeroot, Queen Anne’s lace, rauwolfia, rosemary, Chinese sienna, sesame, shallots, stevia, strawberries, sunflower, tamarind, tea, all varieties of English and French thyme(Thymus vulgaris),wild thyme, toothache plant, tormentil, Bearberry(Uva ursi), vetiver, wintergreen, sweet woodruff.
Just to recap
Remember to always take into account soil pH when deciding what herb to plant in your soil. If you do not know what the pH of your soil is then test your soil and if needs be take steps mentioned earlier to change the pH value over time. Best of luck!
Herbs Growing Tips