By Matt Gibson
Plants that grow in water are called hydrophytes, or macrophytes. Some water plants can grow in water for their entire lives, while others can be propagated, or regrown in water, but need to be transplanted into soil once they develop roots in order to get the nutrients they need to thrive. Water plants that can survive in water indefinitely are split into four different categories: deepwater plants, floating plants, marginal plants, and oxygenated plants. The method for growing plants in water is known as hydroponics.
There are quite a few herbs that can be propagated by putting their cuttings into water, though none of them are true hydrophytes, because none can survive for long periods in just water and once their roots have developed, they need to be put into a soil-like substrate in order to mature. Some water grown herbs can be regrown in water and may be able to stay in jars of water and be harvested while they are still sitting in their water jars. However, most need to be moved to a container filled with soil or planted directly in the ground, and all herbs will have a better chance if they are moved to soil once its roots develop.
If you are thinking about starting an indoor herb garden, or an outdoor herb garden for that matter, all you need is plenty of jars, water, and a friend with an herb garden who is willing to take a few cuttings from their herb plants for you. To take a cutting, just cut a nice piece of stem from a healthy, mature herb plant making the snip right at the leaf node, which is the area of the plant’s stem where the leaves branch out from. Try to find a part of the stem that has two to three leaf sets already starting to sprout. If you cut a stem covered in leaves, remove all but the topmost two or three leaf sets.
If you don’t have a friend with an herb garden who is willing to help, you may be able to find a gardening company that you can order cuttings from which will ship them to your area. When taking cuttings, be sure to use a sharp, clean pair of scissors or garden shears.Using an opaque container instead of a clear container and room temperature water. This will reduce algae buildup in your water jars. However, if you are changing the water out regularly, algae shouldn’t become a serious issue.
Either way, if you can get your hands on some cuttings from established herb plants, all you need to do is stick them in a jar filled with water, place the jar on a sunny windowsill, and replace the water every day or every other day. Within just a few days to a week, you should start to see baby roots beginning to form. Once the roots develop, you can move your plants into containers or move them into the garden. The following herbs can be regrown in water.
Basil (Ocimum basilicum)
Basil is a very easy herb to propagate in water. Just place basil stem cuttings with leaf nodes in a container filled with water and position it in a location that receives good light. Take your cuttings when the host plant has matured, but before it starts to flower. Change the water in the container every few days and make sure that it gets good sunlight in the location that you chose. Once the roots grow about two inches long, move them into containers or transplant them into the garden. For more information, see our article How to Grow Basil.
Catnip (Nepeta cataria)
Catnip is another easy herb to propagate by cuttings. Take your stem cuttings from mature, healthy catnip plants and remove the lower leaves on each one. Stand the cuttings up in water. Change the water daily or every other day and look for new root development within just one week. Once the roots look strong and healthy, move each catnip plant into its own small container filled with sterile potting soil. Water the transplant regularly and keep it in dappled shade until you begin to see new growth. That’s all you need to do. For more information, see our article How to Grow Catnip.
Cilantro (Coriandrum sativum)
Cilantro cuttings must be taken before the host plant starts producing flowers so that the plant will keep its distinct cilantro flavor. Remove the lower leaves from the cuttings and place them into a clear jar filled with water. Once the roots grow long enough, move the rooted cutting into a pot of soil and assign it to a sunny spot. Allow two months of growth before harvesting. For more information, see our article Grow Your Own Cilantro.
Fennel (Foeniculum vulgare)
To take a fennel cutting, cut a stalk from a mature fennel plant down to one or two inches tall, and leave the root bulb attached. Place the cutting into a shallow dish filled with water. Maintain the water level in the bowl so that it rises to the same level as the root bulb. Put the bowl in a location that receives partial sunlight. Change the water every other day. For more information, see our article How to Grow Fennel.
Ginger (Zingiber officinale)
Growing ginger in water requires a little bit of a different process than most herbs. Before ginger can be grown in water, it needs to develop roots in compost. Cut a ginger rhizome into several pieces, each containing a bud. Fill a container with compost and plant each rhizome piece about two and a half centimeters under the soil. Water well and often and keep an eye on its progression.
Use a container that is at least three square feet (or one square foot for each rhizome piece you are attempting to root) and at least four to six inches deep and put two inches of growing medium into the hydroponic container. Check often for germination of the rhizomes, and once you notice new stems and leaves, pull the best looking plants up and rinse all of the soil off of their roots.
Place the baby ginger plants on top of the growing medium and spread out their roots well. Keep each plant at least one foot apart from each other. Pour growing medium over the plants enough to cover their roots to keep the plants anchored. Hook up the hydroponic container to its water source and fertilize the baby plants in two hour increments using a standard hydroponic nutrient solution and keeping the pH level of the water between 5.5 and 8.
Provide 18 hours of light per day from a grow light and let your ginger plants recover in darkness for eight hours. In approximately four months, your ginger plants will develop rhizomes and are ready to harvest. Pull up the rhizomes and wash them off, then dry them and keep them in a cool, dry location.
You can also regrow ginger by soaking chunks of the root for one night in water, then plant them in a container with soil and place the container in a warm, sunny spot. Ginger can also grow and produce leaves in water. To do this, place a piece of rhizome that has developed small roots into a cup or jar of water and change out the water every other day. For more information, see our article How to Grow Ginger in a Container.
To grow lavender in water, just take a three to five inch long cutting at a leaf node from the host plant and pinch off the leaves from the bottom of the stem, taking between three and five sets of leaves from the cutting. Dip the bottom portion of the cutting into some rooting hormone, then place it into water. To help the cutting stand upright, line the bottom of the container with pebbles if needed. For more information, see our article How to Grow Lavender.
Lemon Balm (Melissa officinalis)
Take cuttings from a mature lemon balm plant in the spring or fall and place them in a jar of water. Keep the jar in a warm location with plenty of sun. Replace the water every other day and allow three to four weeks for your lemon balm cuttings to produce roots. Once the roots grow long enough to anchor themselves into soil, move them into containers. For more information, see our article How to Grow Lemon Balm (Melissa officinalis).
Lemongrass (Cymbopogon citratus)
Lemongrass stalks can be rooted in water in two to three weeks time. Cut five to six inch stem cuttings from the bottom of a healthy, mature lemongrass plant and place them into a bowl filled with water. Keep at least half of the cutting above the water line, and never allow it to fall in and become fully submerged. Keep it in a sunny spot and freshen the water up every two to three days. Add some liquid fertilizer to speed up the process. Once the roots are established, move your lemongrass into a soil filled planter and give it a sunny home. For more information, see our article How to Grow Lemongrass.
Marjoram (Origanum majorana)
Midsummer is the best time to propagate new cuttings of marjoram and grow them in water. Be aware that marjoram will take longer to put out roots than some other herbs you may work with, but with patience you can grow marjoram from cuttings in water with success. Take cuttings from the tips of the stems of a healthy plant, and make them about three inches long, choosing sections that do not have flower buds. Remove the leaves from the bottom of each cutting, leaving six to eight leaves on each stem.
Then add the cuttings, cut side down, to a container with room temperature water inside, submerging the bottom inch or two of each cutting. Choose a shady, warm windowsill for your new cuttings to grow, and refresh the water in their containers every two days. For more information, see our article How to Grow Marjoram (Origanum majorana).
Oregano (Origanum vulgare)
To grow oregano in water, begin by taking a cutting from a mature oregano plant that is four to six inches long. Make your cut just below a leaf node (the place where leaves grow from the stem). Remove all the foliage from the bottom two inches or so of each cutting you have taken.
Quickly place the cuttings into a container with an inch or two of room temperature water inside. Find a spot for the oregano to grow that gets dappled or partial sunlight, as too much direct sun can damage the cuttings. Change the water in the container every three or four days. For more information, see our article How to Grow Oregano.
Peppermint (Mentha x piperita)
Peppermint is an enthusiastic grower that is easy to root in water, and it will continue to grow happily without soil. Take your cuttings from a happy, healthy peppermint plant, cutting just below a node (where leaves emerge from the stem). Pull off all the leaves except the ones at the very top. Immediately, add the cuttings to a container with about an inch of water inside. Find a warm spot with plenty of sunshine for your peppermint to grow, and change the water for your cutting every two days or so. For more information, see our article How to Grow and Use Mint.
Rosemary (Salvia rosmarinus)
Rosemary is not the easiest herb to root from cuttings, but if you are persistent, you can get a cutting to grow in water. Just don’t give up if your first few attempts fail to grow roots. Choose cuttings from the new growth on an established rosemary plant that are two or three inches long. Because you are taking cuttings from new growth, the stem should be flexible instead of thick and woody like the older growth of the plant.
You might take several more cuttings than you plan to use so you are prepared if some of them do not take root. Remove the foliage from the bottom two or three inches of each cutting you have taken. Place the cuttings in a container with some water, and find a warm spot for the cuttings to grow that is out of direct sunlight. (Partial sunlight is best). Replace the water in the container with a new batch of room temperature water every two days or so.
For more information, see our article How to Grow Rosemary Herbs at Home.
Sage (Salvia officinalis)
Sage is more than happy to grow in water when you propagate it correctly. Cuttings three to four inches long should be taken from a healthy sage plant in the spring. Place the cuttings in a container of fresh water with the cut end down. Find a spot for the sage cuttings to grow that gets plenty of ventilation (to prevent mildew) and also offers a good supply of sunshine. Make sure to revitalize the water in the container every other day. For more information, see our article How to Grow Sage.
Spearmint (Mentha spicata)
To grow spearmint in water, begin by taking a cutting from a vigorous spearmint plant. Make your cut just below a node (the spot where leaves join the stem of the plant). Then pluck all the leaves but those at the very top of your cutting. Immediately place your cutting into a clean container that holds one inch of fresh water. Choose a location where the cutting will get some sunlight (but keep it out of direct sun—dappled sunshine or spots that get shade in the afternoon will work well).
As with all your cuttings, you will must freshen the water in the container that holds your cutting every day. You can move the cutting to a container full of soil once it shows roots, or you can let it keep growing in the water, whichever you prefer.For more information, see our article How to Grow Spearmint.
Stevia (Stevia rebaudiana)
Stevia is a natural way to sweeten food and drink, and it roots and grows easily in a container of water. Take a cutting from the soft portions of a stevia plant that is strong and healthy, making your cut just above one set of leaves. Remove the foliage from the bottom part of the cutting, but make sure the top of the cutting has at least two leaves. You may use rooting hormone on the end you’ve just cut if you wish, but stevia grows enthusiastically without it.
Right after taking your cutting, place it in a container of fresh water, and find a warm spot for it to grow where it will get plenty of sun. Avoid locations where the sun really beats down in the afternoon, however. Replace the water in the container with fresh liquid every other day. For more information, see our article How to Grow Stevia.
Tarragon (Artemisia dracunculus)
Tarragon is easy to root in water. Take cuttings from a healthy tarragon plant during the spring, as soon as new growth begins to appear. Choose cuttings six to eight inches long from the ends of the stems. Remove the leaves from the bottom third of the stems.
Quickly add the cuttings to a container of fresh water, and find a warm spot for them where they will get plenty of sun (but avoid spots where the sun will be direct in the afternoon, unless there is dappled shade available). Change the water in your tarragon cutting’s container on alternating days. For more information, see our article How to Grow Tarragon (Artemisia dracunculus).
Thyme (Thymus vulgaris)
To propagate thyme and grow it in water, first take cuttings from a thyme plant between the middle of spring and beginning of summer. Choose healthy, bright green sections to propagate, and make your cuts on a node (the part where the leaves join the stem of the plant). Strip the cutting of leaves on its lower portion, and place them in a container of water immediately after taking the cutting. Use a spray bottle to mist the portion of your cuttings that remains above the surface of the water.
Find a sunny windowsill for your plant, but avoid locations where the cutting will be beaten down on by direct sunlight all day long. Some dappled shade or shade during the afternoon will protect the cutting from heat or sun damage. Freshen the water in your container every two days. When you notice that your thyme cuttings are beginning to sprout roots and put out new growth, cut the top of the stem to encourage the new plant to develop branches.
Once there is a substantial root growing from the bottom of each cutting, you can move it to a container of moistened potting soil if you like, or you can continue allowing the thyme to grow in water. For more information, see our article How to Grow Thyme.
There is quite a wide selection of plants that can be easily grown in water. Now that you’ve looked into starting an herb garden by placing cuttings in water, why not check out what other plants can be grown in a glass of water on your windowsill? Click here for fruits and vegetables [Link]. Click here for flowers [Link]. Click here for houseplants [Link]. With so many options to choose from, all you need is more windowsills!