Duckweed is a plant that we can find growing naturally in lakes. It looks like a green blanket placed on water and you can easily grow it yourself. It’s appreciated by many animals, being a natural source of food. Moreover, it keeps mosquitos at bay by not letting them breed on water. Most people choose to grow it as animal feed, for example. Today we are going to learn how to grow duckweed in our own backyards, either indoors or outdoors.
How to Grow Duckweed Indoors
1. Choose the Right Container
The right container for growing duckweed needs to be clear, wide, and long. Though it shouldn’t be very deep, it must hold a minimum of 5 inches of liquid.
2. Use Dechlorinated Warm Water
Fill the container 3 inches with dechlorinated warm water. This can be well or rain water or even water that has been treated with fish conditioner. Of course, you can also use simple tap water and the duckweed will survive. However, it won’t grow as well as it does with the dechlorinated one.
3. Apply Fertilizer
When deciding on how to grow duckweed indoors, it’s a good idea to use special fertilizer as well. Buy aquatic plant fertilizer and follow the instructions on it. Alternatively, you can also use some decayed plant material and place it in the water, but it won’t have the same effect.
4. Stir and Shake
Just like a bartender, you need to stir or shake the container to aerate the water. For the oxygen to be able to come in, you need to break or agitate the surface of the water.
5. Add Duckweed
You can take duckweed from ponds or buy some online. Add it to the container. In case you got the plant from a pond, make sure the water wasn’t contaminated. To clean it, rinse it in warm water.
6. Spread the Duckweed
When spreading the duckweed on the surface of the water, make sure that the leaves are not stacked on top of each other. Leave some empty space on the surface as well. In this way, when the duckweed will grow, it will have plenty of space for new leaves.
You can also check out this video that illustrates the steps above:
How to Plant Duckweed Outdoors
1. Dig a Ditch
If you want to know how to grow duckweed outdoors, you should find out that you need to dig a ditch that is deep and wide. For this, you must have an adequate area: it shouldn’t be low, muddy soil, and it shouldn’t get a lot of rainwater. An important thing to keep in mind is not to make the sides of the ditch gently slope. This will lead to an increased risk of flooding. The slopes around the ditch should be steep, and the ditch needs to be minimum 3 ft. deep.
2. Use Plastic Tarp
Take some waterproof plastic tarp and cover the bottom of the ditch. The tarp should be large enough to cover some extra feet around the ditch as well.
3. Cover It with Soil
The next step in our guide on how to grow duckweed if you do it outdoors is to cover the tarp with some soil. Use stones or similar materials to create a raised edge around the tarp. If you plan to use manure as fertilizer, you should soak something like 1 to 5 pounds of the manure in buckets of water. Do this for a day and then spread the mixture on the bottom of the ditch. Obviously, you need to do it after you set up the tarp.
4. Fill It with Water
There are some online stores that can offer you dechlorinating liquid, for example. Let a foot of the ditch height not covered by water. This helps you prevent any flooding.
5. Let the Water Settle
The next day, let the water settle down. It’s a good idea to cover the ditch with some extra tarp if you want to prevent insects from getting in.
6. Add the Duckweed
After the water settled for a day, you should take off any top cover. Add the duckweed. The proportions should be 1 pound for 5 – 10 gallons. Just like before, you need to make sure that there is enough empty surface area if you want the duckweed to grow.
7. Finish Up
One last step you can take when learning how to grow duckweed is to add other aquatic plants. They need to be compatible with the duckweed, so make sure they can grow together. The point here is that your plant might block the sunlight from reaching other plants, which is why you need species that don’t need much direct sunlight. Unless you already have an established pond, you shouldn’t add fish because they need more than water. Moreover, fish are affected if you add manure, which is yet another reason you shouldn’t do it.
Recently, more and more people started informing themselves on how to grow plants in water. If you’re a fan of that, here’s a clip showing you how to grow duckweed in aquaponics:
How to Grow Duckweed – Tips and Tricks
1. Offer the Right Nutrients
Just like any other vascular plant, duckweed requires the following:
- Micro nutrients;
If you want to offer your duckweed all that it needs to thrive, you can use some hummus, soil or compost tea. Also, add some nitrogen if you want to boost protein levels of more than 40%. In this case, you can use ammonia that comes from animal waste. This is a reason why this plant loves growing in fish aquariums.
Other nitrogen sources are:
- Aged manure;
- Vermiculture liquor;
- Some grey water;
- Chicken coop drainage;
- Fish wastewater, etc.
2. Set the Right pH
In general, duckweed needs a pH between 6.0 and 7.5. If you have plenty of algae in the water, they can produce CO2 at night and thus raise the pH dangerously. The key here is to keep an eye on the pH levels. If you want to cut down on the algae production, cover the surface evenly with duckweed.
3. Harvesting Duckweed
When it comes to harvesting, you can take as much as you need from it. However, you should leave around 1 ½ to 2 pounds of duckweed per each square meter every day. This will help slow down the algae growth or prevent it completely. Moreover, this will help you control the mosquitos, as well as help with temperature or water evaporation problems.
However, you shouldn’t leave more than 2 ½ pounds of wet duckweed on a square meter. In this case, the plant will start self-mulching because of the high concentration.
4. Ensure the Right Water Temperature
In general, duckweed prefers to grow in a water with a temperature of 50 to 90 degrees F. Anything above or below will make the duckweed stagnate. At very high temperatures, the crop will crash. A good idea to control the temperature is to add some light shading from some trees. If you have tall plants, that’s also a good option, just as using some shade cloth.
5. Don’t Move the Water Too Much
Since the duckweed floats on the surface of the water, strong winds may push it towards the edges of the water and make it pile up there. This also leads to self-mulching for the layers found beneath. To make a shield from the wind, you can plant taller food crops around the pond.
6. Grow Duckweed in Several Places
By testing different areas, you can find which one is the best micro-climate for production. Moreover, if it happens for one spot to fail, you still have the rest to flourish.
7. Check the Color
One of the most important things you should know about duckweed is that if it turns white, it’s bad. This plant only turns white when it’s dying. As such, you should check the conditions in which you’re growing it. It may be the light, the water, the temperature, etc.
8. Choose an Appropriate Species
There are plenty of different duckweed species, so you shouldn’t settle just for one. Experiment with more and see which one thrives in your backyard. Some people prefer lemna minor, but this is just a personal choice.
9. Duckweed Flowers
From what it seems, duckweed produces the smallest flower in the world. However, it can be quite hard to notice it. You don’t need to worry about pollination since this plant divides asexually, like an organism with a single cell.
It’s interesting to learn how to grow duckweed in your own backyard if you pay attention to details. Duckweed can grow fast and spread around your pond or container. Make sure you check the temperature and the nutrition in the water. Finally, don’t include fish or algae in the pond. Algae can suffocate your crop, while fish may eat it. At the same time, the nutrients duckweed needs can be harmful for many types of fish, so be careful with that.
Image source: depositphotos.com