Herbs are a breeze to cultivate and can even be grown in pots on the windowsill; however, many gardeners treat them all the same when it comes to fertilisation, which is a big mistake. For example, leafy herbs like basil, mint or parsley thrive when fed ample nitrogen in late spring, as it accelerates their growth and enhances flavour.
On the flip side, woody herbs such as rosemary, thyme and lavender require a markedly different approach to fertilisation. Given that nitrogen boosts leaf production, providing it to Mediterranean herbs can weaken their taste, make the plants more fragile and susceptible to disease. If leafy herbs are your choice, they should be fertilised once monthly with a nitrogen-heavy fertiliser, or you could use homemade alternatives like teabags or spent coffee grounds.
Meanwhile, those cultivating hardier woody herbs like lavender, rosemary and thyme should opt for just a light feeding in spring to fortify them.
Herbalist and Simply Beyond Herbs founder Vladka Merva has imparted a straightforward method to nourish woody herbs using crushed eggshells.
She said: “Eggshells are a great source of calcium that seeps into the soil as you water it.
“Calcium is important for plant growth and its nutrition as well as for the soil.
“It helps to maintain chemical balance in the soil and improves water penetration.”
Boosting your woody herbs with calcium not only invigorates their health but also stimulates root growth, shielding them from widespread ailments such as blossom end rot.
This nutrient addition can also increase soil alkalinity, a condition adored by herb varieties like lavender and rosemary.
Moreover, eggshells, with their natural edginess, act as a deterring barrier against pests that may encroach on kitchen-grown herbs, often a magnet for insects inside homes.
Vladka said: “Crushed eggshells serve as pest control. Slugs, cutworms or other insects are put off by the crashed pieces of eggshells and rather leave.”
Here’s a guide on using eggshells to give your woody herbs an edge:
Firstly, let the eggshells dry out in a warm spot, then shatter them with a rolling pin to speed up decomposition when they’re worked into the soil.
Then, simply scatter the crushed shells around your lavender, rosemary or thyme plants.
However, for those cultivating lavender, thyme or rosemary indoors, eggshells can be ingeniously repurposed as novel plant pots.
Carefully slice off the top of an egg with a sharp knife, ensuring the bottom remains whole, then cleanse them well to eliminate lingering yolk, which could attract pests or mould.
While damp, perforate a hole at the base of each shell using a needle.
This drainage is crucial to prevent water accumulation, protecting the well-being of your potted herbs.
Utilise a tablespoon to fill each eggshell with soil, leaving a one-centimetre gap at the top.
Most garden centres stock herb-specific soil, but for woody herbs, you’ll need a light, sandy and slightly alkaline variety.
Next, just sprinkle a few seeds into each eggshell and label them with the name of the herb using a permanent marker.
Water daily, position in a sunny spot, and before you know it, you’ll have a flourishing herb garden.