If you have attempted a windowsill herb garden in the past and met with dismal failure, the problem may have been with the soil. To make your next windowsill garden a success, choose the best soil mix for herbs for container gardening.
Container Gardening Soil Basics
Container herb gardening is an excellent solution for anyone who would like to have fresh herbs available year round. All plants need the proper soil to thrive. The best soil mix for herbs for container gardening is lightweight, well-drained and well-aerated. Drainage and aeration keep the soil loose making it easier for the roots to absorb nutrients and water from the soil. Garden soil is a poor choice for container gardening. It is usually heavy, dries out quickly and compresses causing poor aeration.
Over-fertilizing herbs will cause rapid, weak growth that will be low in the essential oils that give herbs their flavor and aroma. A container-grown plant has a limited amount of soil available from which to draw nutrients. Some provision needs to be made to provide the nutrients the herbs need without overdoing it. Herbs growing in soil mixes that do not contain compost or worm castings will benefit from fish emulsion fertilizer applied at half-strength every few weeks.
When starting a window sill herb garden from seed, a special seed-starting mix should be purchased. This specialized mix may be soil-less or soil based and can be found in garden supply centers. Never use soil from the garden or backyard. It contains weed seeds and pathogens that can be detrimental to seedlings.
Whether the plant is being transplanted from the garden or is purchased nursery stock, the pot makes a difference in the soil mix. Unglazed clay pots wick moisture from the soil to the outside of the pot, so the soil dries out quickly. When using clay pots, the soil will need more water-holding ingredients. Adding some water-retaining granules, vermiculite or peat moss to the soil mix will overcome this problem.
Types of Herbs and Their Requirements
The Mediterranean herbs like dry conditions and benefit from a more porous soil mix. Adding extra sand or perlite to the mix will make the mixture more porous. Some examples of Mediterranean herbs are lavender, oregano, rosemary and thyme.
Moisture and shade-loving herbs need more moisture-retaining ingredients and organic matter than their Mediterranean cousins. The addition of compost, peat or coir will increase the organic material in the blend. Basil, chives, mint and parsley are herbs that fall into this category.
This simple blend can be made from easily located ingredients.
- 2 parts potting soil
- 1 part perlite or sand
- 1 tsp ground limestone per 5" pot
This mix has enough nutrients that supplementary fertilizing should not be necessary. Top dress the plants each year with worm castings and bone meal worked into the top few inches of soil.
- 5 parts peat-based potting soil
- 1 part perlite or sand
- 1/2 cup worm castings and 3 tablespoons bone meal per gallon of soil mix.
The best soil mix for herbs for container gardening can be formulated by following one of these recipes and amending it for the type of herb being grown.
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