The old adage: you are what you eat. It bears a lot of truth, especially when it comes to container planting. To have success, plants need to draw up water with nutrients and minerals. Most potting soils available on the market are soil-less mixtures. Peat mainly, with added vermiculite and or perlite. With soil-less mixtures, you will have to add synthetic or composted fertilizers to keep nutrients available to the roots, before several waterings will leach them out. Ah, no thanks... I rather use more nutrient retaining soils.
In my experience, a mix of several elements is key. Herbs have significant properties we rely on and you want the plant to thrive and bear the flavours and medicinal goodness and flavours that we need. So why plant them in soil-less mixtures and expect good results? That just doesn't add up.
I compost. Not all kitchen scraps, but a LOT. Coffee grounds, veggie skins...egg shells, anything that will break down relatively quickly - for next year's batch. I also compost all my plant cuttings, autumn leaves and grass clippings. This makes a fabulous compost mixture that is fortified. But, I also balance other aspects too.
This is my potting soil recipe:
First: grab a wheel barrel or large vat (if you're lucky, you may even have a potting bench). Start by adding 1/3 compost, 1/4 sand, 2 cups perlite, 1/2 cup mycorrhizae for herbs and vegetables, and an 1/4 cup organic vegetable fertilizer. If you're like me, and plant herbs in a pot year to year, I reuse about 1/3 of the pot's original soil. Beneficial living organisms from the year before are still contained in there. You want to keep that cycle going by inviting them into the new mix.
|Last year's old plant material. Removed all the roots, and dead bits, but kept half of the soil in the wheel barrel. NOTE: if you had diseases and problems with your planters last season, then DON'T reuse last year's soil. Begin with new soil.
This is how the various additives look:
Mix thoroughly together.
One key aspect of growing herbs, if you're going to plant several together, plant similar sun/hot to shade/moist selections together. I like planting "hot herbs" in terra cotta pots. Terra cotta pots heat up in the sun. You want a dry, Mediterranean conditions, and they will heat up if you keep the pots on hard landscaping surfaces.
Plastic pots work well to retain moisture and I use them for "cool herbs".
Here are some groupings that grow well together:
Hot/Dry: Rosemary, Thyme, Sage, Oregano, Marjoram - these all like drying conditions and less waterings.
Cool/Part Sun: Basil, Chives, Parsley, Coriander - these all like moist conditions and can tolerate a bit of dappled shade.
With the hot/dry loving plants, you may want to even add more sand, to promote drainage. The amount of sand may vary, depending on your compost. The more organic material that hasn't broken down, the more sand you will need. These hot plants hate roots standing in water.
Place pots in a sunny position. Place water trays beneath to catch water from leaching out too much fertilizer when you water.
Every 3rd watering I add compost tea that I make (here's the link to that post) for an added boost.
Pinch segments back for your culinary needs and try not to let the plants bolt - meaning, not let them go to seed.
If you have noticed, I have several other little plants that have hitch-hiked their way into my soil. This year I had morning glories, tomatoes and bidens germinate from seed. Hey, why not! They add some colour and joy to this little spot by the kitchen entrance.