Struggling with weeds in your herb garden? Learn simple ways to control weeds naturally, reduce growth, and protect your herbs.
What are weeds?
As the old adage says, a weed is any plant that’s growing where you don’t want it. These may be wild plants that are edible or ornamental in their own right. They may even be garden plants—herbs, flowers, or vegetables—that have overrun their allotted space and started spreading into their neighbors’ territory.
You’ll need to control weeds if you want your garden to flourish. This article suggests some ways of doing that without using ecologically damaging herbicides.
How Do Weeds Affect your Herb Garden?
Weeds can cause several kinds of problems in your herb garden, depending on the type of weeds you have and the herbs you’re trying to grow. Here are the most common:
Crowding
If you’re growing annual herbs, or perennials that you cut back to the ground in the fall, the new growth will be small and tender in the spring. At this stage, it can be overgrown and choked by aggressive, fast-growing weeds like quackgrass or mint. I lost a planting of chamomile this way, the delicate seedlings were buried and smothered.
Competition
Weeds take moisture, light, and soil nutrients that your herbs need in order to thrive. Sun-loving herbs like basil and rosemary won’t do well if they are shaded by taller weeds. In dry years, when you need to water, you don’t want that precious resource going to weeds.
Disease
Weeds growing close against your herbs reduce air circulation and hold moisture from dew and rain against the stems and leaves. This can lead to mildew and fungal diseases. My lavender is large and robust enough that it’s not easily outcompeted, but it sometimes suffers from septoria spot. I’ve found I have fewer problems when I keep it well weeded.
Know Your Weeds and How to Remove Them
Different types of weeds require different approaches. Local gardeners or your local extension office can often tell you which weeds are most common in your area and how to deal with them. Some gardeners also use plant ID apps to help identify weeds.
Annual vs. Perennial Weeds
Annual weeds live for one growing season or less, so they have to be constantly re-started from seed. Those seeds need open ground to root and sprout in. Keeping the ground covered with mulch–or with densely planted perennial herbs–can help reduce your problems with annual weeds. Pulling the weeds before they go to seed is also an important step in control.
Perennial weeds regrow from their roots year after year and are much harder to remove. Some can grow back from even very small root fragments. Quackgrass is particularly notorious for this.
You can try to remove them by hand-digging and sifting through the soil to remove roots. Another option is solarizing the soil by covering it with clear plastic and sealing the edges, leaving it in place for several sunny weeks.
The downside of this approach is that it also discourages earthworms and other beneficial soil organisms. Solarizing may kill these, and removing all organic material from the soil removes their food sources and shelters.
Or you can decide to live with some recurring perennial weeds. If you keep tearing their tops off, they’ll stay small. The weed management techniques described below can slow them down.
Freestanding vs. Vining Weeds
Viny or clinging weeds offer a particular challenge. Here in upstate NY one of our worst weeds is Convolvulus. In the fields it’s wild morning glory, a very beautiful plant. In the garden it’s called bindweed and loathed by gardeners. Its tough thin quick-growing vines wrap tightly around the stems of garden plants; its leaves cover the leaves of their support plants. They can shade out even large vigorous perennials.
Trying to tear the vines from the branches is a slow process which often leads to breaking the plants I’m trying to rescue. If the bindweed has gotten itself firmly attached, I just tear out a short section right above the ground. The upper vine, unsupported, will quickly wither and die, becoming brittle and easy to remove.
Garden Management to Reduce Weeds
There’s no such thing as a completely weed-free garden, but good management can slow weeds down and give your herbs a better chance to thrive. Here are a few techniques to consider:
Mulching.
Keeping the soil around your herbs covered will make it harder for weed seeds to settle into soil and germinate. It also slows the growth of perennials coming up from buried roots. Mulching with organic materials also helps to retain moisture in your garden soil, to buffer temperature changes, and to enrich your soil.
Here are a few organic mulches that I’ve found useful:
- Grass clippings make a short-lived mulch that adds nitrogen to soil as it breaks down. Keep clippings no more than 1″ deep or they turn slimy. (Don’t use clippings from a lawn treated with pesticides or herbicides!)
- Sawdust is a slow-decomposing mulch that adds lignins, which have anti-fungal properties, to soil as it breaks down. Only use sawdust that’s aged at least a year. Fresh sawdust will take nitrogen from the soil as it breaks down.
- Hay and straw are soil-cooling mulches which last a fairly long time. Hay has weed seeds in it; straw doesn’t.
- Rabbit manure is the only manure I know of which can be applied to the soil without being composted first. It adds nitrogen, potassium, and phosphorus to soil as it decomposes.
- Coffee grounds are quick to break down and high in nutrients, but also acidic, so should be used only around plants that prefer high acidity.
- Shredded leaves or pine needles are slow to break down. Pine needles are acidic, though some Extension articles say they break down too slowly to acidify soil.
No-Till Gardening
Tilling your soil–or even turning it over with a garden fork–breaks up the roots of perennial weeds, and a new weed grows from each fragment. It also creates a soft, fluffy seedbed for weed seeds. You may have fewer problems with weeds if you don’t till.
Well-Timed Weeding
Even with good planning, you’ll still need to pull weeds. If your gardens are extensive you won’t have time to pull every weed. Prioritizing can help you make the best use of your weeding time.
I focus on removing these types of weeds:
- Weeds growing among small, delicate, or newly sprouted plants, like young chamomile or basil.
- Weeds crowding plants that are prone to fungal disease, like lavender or rosemary.
- Weeds that are flowering. If you let them go to seed, they will multiply and become a bigger problem soon.
Wrap Up
Weeding is a constant and necessary chore, but with a little care and thought you can reduce the time you spend on weeding and give your herbs a better chance to thrive.