Oregano (Origanum) takes its place in the mint family as the more stable relative, slowly expanding as a clump instead of runners -even getting woody with age.
The root system is thick, but not specially deep, allowing some interplanting if you just give other plants some space. A buffer of two to four inches around a new plant to give some time to establish before the oregano grows against it is adequate.
From then on a little mulch placed around the prefered plants makes things very happy. The oregano even provides some of the mulch. Growing up and dying back every year, it leaves a lot of sticky looking stems over winter that in spring can be gathered up and conveniently stuck around the plants you want to encourage. Depending on the ratio of oregano to plants to be mulched, the oregano can provide enough mulch to hold itself back.
I am just introducing oregano to the food forest, but have seen it well used in other gardens. Martin Crawford is one good example. In “Creating a Forest Garden” he shows the progression from a bed freshly denuded of grass by laying canvas over the ground, to a mix of annual mustard and tranplanted oregano, to the next year when the mustard is gone and the whole thing is a thick mass of oregano.
This technique can be applied for many other groundcovers. Usuaully I opt for the violets, creeping charlie, or mint that follows by its own invitation. If you’re lacking those, or want something more tame (well, violets are pretty tame, but the other two need watching) oregano is a good alternative.
Oregano is a bit more attractive than these naturally occuring groundcovers, for one, because it is seldom recognized as a weed. Personally I don’t care about that a lot. I like the looks of creeping charlie running wild. But I do like the ornamental effect of oregano. I’m drawn to the gold, which is more like neon green with touches of gold. There are several other colors and varieties. Most of these colors come in variegated form too.
Another point for oregano is its highly antibacterial essential oil. I have unfortunately never come across a study showing any benefit for other plants around it. The fact that it is so effective as an antibacterial, even when compared to other essential oils, is suggestive of good effect.
One point that suggests an appreciable effect: the main constituent, carvacrol, is volatile. In fact it can makes the majority of the volatile oils in the plant -sometimes over 90 percent. If you have walked on a hot day through a garden where oregano grows, you probably noticed the scent can be delightfully prevalent. It serves to reason oregano in the garden would give some small antibacterial effect.
It is also quite attractive to a range of wasps and many other insects that congregate on its flowers. So add beneficial insect attractant to the list of functions it offers.
If not for the benefit of the garden and other plants’ growth, its strong scent and flavor benefit the food you harvest. Oregano is used to flavor lots of foods. Just think of pizza.
With all these functions, there is little chance oregano won’t somehow make it into the garden. Let me know how it works for you as a groundcover. I’ll update on mine in the near future.