One of the coolest things about growing herbs is that it’s really easy to make more of them! Here’s how to propagate perennial herbs to make your garden bigger or increase your harvest.
There are three ways to make new plants. Some of the methods are suited better to some plants than others. Note that collecting seeds and planting them is also a way to make more plants, but I’m focusing solely on propagation for this post.
Many culinary herbs are perennials and that means they come back year after year. Perennial plants are simply herbs or flowers that typically die back in the fall, going dormant over the winter. In the spring, they put up new growth, often gaining in size. It’s very easy to grow completely new plants from cuttings or divisions of those you (or friends or family members) are already growing.
Some herbs, like basil or parsley, are annual or biennial herbs in many places, meaning they live on one or two years. Because they can grow so vigorously, these non-perennial herbs can be very easy to propagate during their one season. Therefore, I’ve included them in this guide.
For further information on basil, check out Making More Basil.
Keep in mind that most perennial plants want to spread and replicate themselves. Some even NEED to be divided every so often to maintain vigor. Knowing this, it’s better to start with just a few plants and a plan to turn them into more. You’ll save money and you won’t run out of garden space.
HOW TO PROPAGATE PERENNIAL HERBS WITH CUTTINGS:
Many plants will grow roots from a single cut stem or stalk. Generally referred to as ‘taking a cutting’, this is one of the easiest ways to create new plants.
For best results, take cuttings from established perennials that have at least one full growing season under their belts.
Once the plant has started to put up new growth in the spring, it’s ready to donate a cutting. Clip off a small section, at least 3-5 inches tall. This is typically done just above where two stems fork.
Both spring and fall are great times to propagate herbs. Early in the year, it’s best to take the cuttings from new growth on the plant. Later in the season, you can take cuttings from new or old growth. Old growth usually takes longer to produce roots but can ultimately make a stronger new plant. In fall, leave a few weeks before your first frost date for the newly created plants to establish.
After you’ve taken the cutting, remove most of the foliage along the stem. This allows the plant to focus energy on making roots instead of supporting leaves. Do leave at least two pair of leaves, however, as the plant needs to be able to photosynthesize.
Put the cutting into a glass of water or into a container filled with potting soil. In the water or soil, the buried stem will start to develop new roots. It’s possible to root cuttings directly into the soil where they will grow but this should be done in temperate weather. Those cuttings will need to be watered daily until new growth is visible. The advantage to rooting cuttings in a container is that it’s easy to move the container to keep the fragile cutting out of harsh weather or searing sun.
If you put cuttings in soil:
Keep in mind that the rate of new root development will vary from plant to plant. Woodier plants, like thyme, rosemary or lavender typically take longer to start making roots. By contrast, plants like oregano and chamomile both form new roots very quickly. The best course of action is to take several cuttings and carefully monitor their development.
Is it better to root cuttings in water or soil?
It depends on the plant, honestly.
In my experience, basil and oregano both love to make new roots in water. Thyme and rosemary, which have thicker, woodier stems, seem more resistant to rooting in water, but it is possible.
Some people feel that plants develop better roots and are generally stronger if they are rooted in soil instead of water. The benefit to rooting in water is that you can easily tell if the plant is making new roots. It’s very easy to simply stick a cutting in a glass and wait. If you use water, be sure to change it daily.
A benefit to rooting cuttings into soil is that transplanting the new plant is less stressful. The roots won’t be as disturbed because you can scoop out the soil and put it straight into the hole you’ve dug.
Whether you use water or soil, wait to see new growth develop on the plant before moving it to the garden. New growth is a sure sign the plant has formed roots and that the roots are working to take up nutrients. Think of new growth as a literal green light to transplant!
Note that many people use rooting hormone when putting cuttings into soil. This is an inexpensive powder that can help roots form more quickly. It’s helpful but not at all essential. Try it and see if you like it, but if you don’t have any, go right ahead and root your cuttings.
HOW TO PROPAGATE PERENNIAL HERBS BY ROOTING EXISTING PLANTS:
This is very similar to taking cuttings, but with a key difference. The section of plant you are encouraging to form new roots doesn’t get cut off of the original plant. Instead, you take a small branch or section of the parent plant, bend it gently over to the soil and then cover it with more soil. The parent plant continues to provide nourishment for the section, but the soil around it encourages it to make roots. Once the section starts to make new growth and resists being (gently) tugged, you can usually assume it’s made roots. At that point, cut the section off just before the buried portion, very carefully dig the section up and admire your new plant!
What’s great about this type of rooting is that the parent plant does most of the work in nourishing the section and you can do this at any point in the growing season. The buried section doesn’t need to be protected from extremes of climate and it doesn’t need special care or extra watering. If you aren’t ready to remove and transplant the new plant, you can even leave it on the parent plant over the winter.
The drawback is that you have to work with a section of plant that is low to the ground or otherwise easy to force (gently) into contact with soil. There’s also a limit to how many pieces you can try to root at a time, since space usually ends up being a concern. This method can also take longer. But if you’ve got time and a little extra room around your parent plant, this is a great way to start new plants.
You’ll need to remove any growth from the section you’re burying so it doesn’t rot – but you need to leave the growth on the end of the section intact.
This technique works great for propagating rosemary, lavender, thyme, oregano, mint and most other plants that have wide, flexible growth. It’s not a good choice for plants with very sturdy, upright stems.
While it’s often easiest to bury the section in the ground, you can also put a pot full of soil next to the parent plant and bury the section in that.
HOW TO PROPAGATE PERENNIAL HERBS BY DIVISION:
This is the most violent way of making more plants but it’s also very effective! The other methods can be used on younger plants, as long as they have enough foliage to survive having a piece harvested but a plant should be mature and well-established before being divided. For most plants, that means at least one full growing season because the parent plant needs to have ample, healthy roots and foliage.
Division should be done only at the beginning of the growing season or the very end. It’s very stressful for the parent plant, so it’s best to avoid extreme temperatures.
Most of the time, you’ll have to dig the parent plant up completely. Once it is on the surface, use a sharp shovel, shears or a knife to cut the root system in two. Some plants with softer growth and roots can be pulled apart, but older, tougher plants will require a tool. The goal is to separate the plant quickly and cleanly, with the least amount of damage to the roots. Some roots WILL end up severed or damaged, but the majority need to survive intact in order for the plants to survive. Work quickly because the longer the plants are out of the soil, the harder it will be for them to recover.
It’s best to divide plants early in the day when temperatures are mild. All of the plants need to go back into soil as fast as possible, so have the holes dug or the containers filled and ready before you dig up the parent plant. Quickly, but carefully, put each section into its hole, fill solidly with soil and then water thoroughly.
The soil needs to be firm around the roots but not compacted – simply filling the hole thoroughly and then pressing with your hands should be sufficient. The water will ensure the soil settles around the roots and will help the plant recover. Even if the ground is wet or it’s raining while you’re planting, you should water the new plants in their holes!
What happens after re-planting
Once the plants have been divided and planted, they’ll need to be carefully monitored. Don’t be shocked if they collapse limply within a couple of hours. Being dug up, severed and reburied takes a lot of out of a plant! Within a day or two, they’ll perk back up, provided you keep them watered and avoid doing this in hot weather. If you are dividing plants at the end of the growing season, sheer back the top third of new growth before you dig the parent plant up. A haircut means there’s less foliage for the plant to support while its roots recover from the indignity of being cut and replanted.
What’s great about dividing plants is that you immediately double your plants, at least. Very large plants can be split into three or four new plants, but the parent plant should several years old and have a substantial root system. Each new plant need to have good roots and plenty of leaves to survive the process, so if you’re in doubt, it’s better to divide into fewer new sections.
Thyme, oregano, chamomile and mint all respond well to division. Shrubby herbs like lavender and rosemary do not.
HOW TO CHOOSE THE BEST METHOD OF PROPAGATING PERENNIAL HERBS
Some herbs really don’t seem to care how you treat them, they’ll make new roots and keep on going. Others are more delicate or more resistant.
As a general rule of thumb:
Some Herbs That Root Well From Cuttings:
- Thyme, rosemary, lavender, oregano, mint, tarragon, chamomile, basil (technically an annual in most zones, but super easy to propagate), marjoram, lemon balm
Some Herbs That Propagate Well Via Rooting:
- Thyme, rosemary, lavender, mint, oregano, marjoram
Some Herbs That Propagate Well Via Division:
- Thyme, oregano, mint, chamomile, tarragon, parsley
In general, the method you pick will depend on both your preference and the age and condition of the parent plant. Younger herb plants won’t handle division very well while some older perennial herbs actually NEED to be divided once in awhile for optimal health. Some herbs are very prolific, like mint, oregano and thyme, so it is very easy to propagate them. Others, like rosemary, need more time and patience.
A final note that some herbs will flower and then go to seed. This is another way to make more plants, but you should wait until the end of the season or until you’re done harvesting from the plant. Flowering changes the flavor of the plant and often saps the plant’s vigor. Letting herbs go to seed is great for annuals, like basil or cilantro.
SUCCESSFULLY PROPAGATING NEW HERBS
In the image above, most of the leafy green growth is Greek oregano. All of the oregano in the photo, plus another fifteen foot section of bed, was propgated by rooting cuttings directly into the soil. Soft stemmed plants are happy to make new roots provided they are watered daily.
The upright, shrubbier looking plants in the foreground are English thyme. They are part of a forty foot hedge of English thyme plants that borders this area of the garden. All of the plants were propagated from only three parent plants by cutting off sections that had been laid over in the soil to form new roots or by dividing existing plants.
The thyme and oregano pictured were propagated from a total of seven parent plants. In the space of only two growing seasons, all of these plants have formed and grown. Because oregano is so happy to spread itself, I use it as a ground-cover, in addition to a culinary herb and a part of my chicken garden. Upright herbs like thyme and rosemary form hedges to border my vegetable garden. Neither would be economically feasible if I had to buy enough plants at the outset to cover the area. In addition, perennial herbs spread, so it’s far better to start with a few plants and a plan for propagating them than to buy tons and run out of room.
As a special bonus, when you join you’ll receive Splendor on a Shoestring, my guide to finding silver, china, linens and other home items on a budget.