How and when to prune your herbs

The mention or thought of the word “pruning” can strike a slight amount of fear in the hearts of many gardeners. Cutting back or trimming your precious plants and herbs seems contradictory to good growth and daunting at the same time. Pruning is an important part of herb garden management though. Just like getting yourself a haircut, trimming your herbs not only encourages better, and new growth but it also keeps them looking nice at the same time.

With a little knowledge and understanding of what proper pruning is, the benefits it provides, when and how to do it, and some considerations to keep in mind, you no longer need to fear the process. Instead, it will be a useful management tool!

What is pruning?

Besides providing your plants with all the resources they need to grow – sunlight, water, and plant essential nutrients - another important part of growing herbs indoors is pruning them. 

Simply put pruning is the process of selectively removing plant parts such as branches, buds, or roots. In some cases, this means clearing away injured, infected, or senesced parts of the plant to foster strong, healthy growth.

In the case of indoor herbs or other plants, this can also mean trimming the foliage to prompt new leaves to grow and generally care for your plants.

Keeping your herbs pruned encourages them to continue to grow and provide new material for you to harvest and use for culinary or medicinal purposes.

The benefits of pruning herbs

Even the most experienced gardeners may cringe at the thought of pruning back their flourishing plants, but there is good reasoning behind the practice. Regular pruning provides the following benefits to your herbs.

• Prevents plants from crowding neighboring herbs or outgrowing their designated space. Herbs grown indoors are often grouped together more closely or have a limited amount of real estate in which to grow.
• Opens airflow within the center of the plant. Increased air movement prevents insect pests from settling in and also reduces disease problems and fungal infections.^[1]
• One of the most important benefits is that pruning will encourage your herbs to become fuller or bushier. Pruning removes apical meristems - the tips of newly growing shoots at the tops of the plant - hindering apical dominance.^[2] When the apical meristems are removed lateral meristems are forced to undergo cellular division; plants grow outward instead of upwards. Plants are programmed to grow upward; when these growing points are removed through pruning, it “tricks” the plant into growing outward instead.
• Maintains an aesthetically pleasing shape. Plants stay looking neat instead of disheveled and overgrown, adding positively to your home’s decor.

How to prune your herb garden

Trying to figure out when the best time to prune can be a challenge when it comes to your outdoor plants. You have to consider the growing season, if the plant blooms or not, if it’s a perennial or biennial plant, etc. Thankfully figuring out when to prune your herbs is a much simpler process.

With most herbs there really isn’t a bad time to prune them; these happy go lucky plants will enjoy the trim and keep putting out new growth.

• Fast growing plants like basil, mint, and dill benefit from frequent pruning. For these herbs, a small amount of pruning can result in substantial new growth. This is partly what makes herbs so attractive for indoor gardening - they grow quickly and can be harvested often for fresh plant material.

• It is best to prune when your herb plant is actively growing. Start off by giving them a good prune in the early spring as growth takes off for the season. Even though you are growing them indoors, your plants will slow down their growth during winter because of decreased temperatures, and shorter day lengths.

Tools needed

Pruning your herbs is a simple process that doesn’t require much for equipment, helping add to the ease of the process.

Tender, soft-stemmed herbs

If your herb collection consists only of plants like as basil, cilantro, parsley - all plants with tender, soft stems - the only tools you need are your fingers. Using your fingernails you can “pinch” off the material you want to prune. Nothing else needed! Just make sure to wash your hands well before you start. 

Woody-stemmed herbs

Herbs that have more woody stems will need some sort of cutting implement to cut through branches. Since they are typically much thinner in diameter than trees or shrubs found outside a pair of sharp scissors should suffice. If you want to keep your kitchen or sewing shears solely for their purpose intended, invest in a pair of small pruning shears.

When using scissors or shears you’ll also need a disinfectant such as rubbing alcohol or bleach to clean the blades before and after you prune your plants.

Clip a little lower than here when pruning basil. 

How to prune

1. Start off by assessing your plant. Determine where you should prune it and how much plant material needs to be or should be, taken off in the process. Establishing a game plan before you start helps to make sure you don’t remove too much of the plant and cause it stress.

2. If using scissors or pruning shears for thicker-stemmed plants clean them well by wiping down the blades with rubbing alcohol, a diluted bleach solution, or some other type of disinfectant. This reduces the chances of spreading diseases or fungal infections from an infected plant to a healthy one.

3. Begin pruning at the top of your herb plant, making sure to leave the sturdier leaves at its base. These older sets of leaves provide support and the main structure for the plant, helping to keep it erect.

4. Remove horizontal growth on the plant or any branches/stems that are growing in towards the center instead of outward to open it up. Doing so creates good air flow through the middle of your herbs and reduces the incidence of insects pests, diseases, and fungal problems.

5. Using your fingernails or your chosen cutting tools, make a clean cut where the leaves attach to the stem. Work on one section of the plant before moving to another.

6. Periodically step back to assess your work, ensuring the pruning is even or symmetrical on the plant. If there is an area that is lopsided carefully try to even it out to maintain a pleasing shape.

7. When the desired amount has been pruned make sure to remove any cut material that may have fallen down inside the center of the plant. If left, it may attract pests or trigger diseases as the material decomposes.

8. Don’t throw all of your trimmings away! Use the cuttings from your fresh herbs in recipes, dry them down for later use, or use them to propagate new plants in your herb garden!

Special considerations

Even though herb plants are pretty forgiving when it comes to pruning, making it hard to do it incorrectly, there are still some important concepts to keep in mind.

• Know if the type of herb needing pruning is herbaceous or evergreen as this influences the process. Herbaceous herbs lack a woody stem above ground and should only undergo a light pruning or “tipping”; these plants would die back to the ground every year to survive the winter. Evergreen herbs have woody stems and hold their leaves throughout the winter and should be “hard pruned” no more than 1 or 2 times a year.

• Regardless of the type of plant, never remove more than ⅓ of it during any pruning event. Taking too much will negatively impact growth and can stunt the herb.

• Lavender can withstand a heavier pruning than other herbs. When pruning your lavender plants cut it back to 3 to 4” above the soil surface once or twice a year.

Conclusion

Pruning your herb garden keeps plants looking neat and tidy while keeping them strong and healthy. It encourages lateral growth while maintaining adequate airflow throughout the center of the plant. Most herbs in your garden will benefit from regular, frequent pruning and require little more than your fingers and a plan of attack to start.

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1. Katsaruware, R., Mafongoya, P., & Gubba, A. (2017). Responses of Insect Pests and Plant Diseases to Changing and Variable Climate: A Review. Journal of Agricultural Science, 9, 160. doi: 10.5539/jas.v9n12p160 ↩︎

2. Barbier, F. F., Dun, E. A., & Beveridge, C. A. (2017, September). Apical dominance. Current Biology, 27, R853 & R865. Retrieved from https://www.cell.com/current-biology/pdf/S0960-9822(17)30560-2.pdf ↩︎