How do you make water flow uphill without a pump? Magic?
Nope, capillary action. That’s how!
A capillary mat is an absorbent mat that sits underneath greenhouse plants and allows for a super-convenient watering system. The capillary mat acts as a wick, pulling water from a reservoir as needed, creating a self-watering system. Sometimes mats are used in conjunction with rims or a border to ensure liquid stays inside, and sometimes they are combined with irrigation systems. Now that DIY projects are becoming popular, many greenhouses and conservationists have developed new methods for people to create capillary mats from the comfort of their own homes!
This article is a greenhouse capillary mat DIY guide, and discusses how to make these mats. It also looks at some options for purchasing ready-made setups.
- 1 Why Should Gardeners Use Greenhouse Capillary Mats?
- 2 Greenhouse Capillary Mat DIY Guide
- 3 How to Make a Capillary Mat
- 4 The Best Capillary Mat Materials
- 5 Pre-Made Greenhouse Capillary Mat Setups
- 6 Providing Water to Your Capillary Mat Setups
- 7 Conclusion
Why Should Gardeners Use Greenhouse Capillary Mats?
Capillary mats are an old form of greenhouse irrigation that maximized growing space. The use of a fibrous material that absorbed water meant pots could be placed directly on the surface and have water transfer from the mat directly to plant roots. The system took up no space and plants could literally be grown pot to pot. This particular method was popular for decades, gaining steam in the 1960s to mass-produce flowers like the Easter lily.
However, the capillary mat fell out of favor in the 1990s as new irrigation systems swept greenhouses. These systems took up more space but were supposedly more effective at transporting large quantities of water to needy plants. New irrigation systems were especially common in large greenhouses.
These irrigation systems look something like a souped-up version of a DIY garden irrigation kit, and basically involved running small water pipes to individual plant pots.
Many of these systems are not the best for the average greenhouse owner, though. If you have lots of small pots, these can be a headache to run, and if you change your configuration, you’ll have to change your watering setup. They often don’t work well for someone who just has a basic greenhouse for those plants.
That said, a system like this in combination with a capillary mat setup (where the irrigation system is filling the reservoir, as opposed to watering individual pots) can be quite effective! Also, consider a seedling heating mat to get your plants started early.
The capillary mat is inexpensive, simple to make, can be maintained easily, and can even be made at home! For these reasons, capillary mats are once again on the rise. They are even biodegradable if made correctly, which is important for many greenhouse owners who strive to be environmentally friendly and leave a small carbon footprint behind.
Greenhouse Capillary Mat DIY Guide
Now that someone knows they want to DIY a capillary mat, what do they need?
There are a couple of different ways to develop a mat, but they all require the same basic materials. Capillary mats are surprisingly easy to make. The standard version requires the bare minimum of products.
At its truly most basic, you could just place the capillary mat on a table, put the pots on the mat, and stick one end of the mat in a bucket filled with water.
Here’s an image of a capillary mat in its most simple form, from the Agrarian Ltd Capillary Mat:
The image shows several plants on a mat, with the end of the mat submerged in water in a sink, below. The water flows up the mat and saturates it. The plants are in contact with the mat, and take up the water as needed.
Now, typically there is more to the setup than this. This setup results in the wet mat being in constant contact with the table or bench, which in many cases will lead to mold or mildew. Rotting and nastiness.
Typically, gardeners will use some sort of waterproof material beneath the mat to ensure that the bench or table isn’t damaged by the constant presence of water.
Additionally, frequently there’s a rim around the setup to ensure that water is held in place.
How to Make a Capillary Mat
The actual process of capillary mat making is deceptively simple.
The materials you’ll typically want are poly sheeting, capillary matting, and potentially a rim material.
Last update on 2021-05-14 / Affiliate links / Images from Amazon Product Advertising API
For a rim material, you have a wide variety of choices, and you may well have the materials left on hand. Extra pieces of vinyl siding, cardboard, plastic trays, any sort of flexible plastic will likely do. Secure them in such a way that they form a rim around your capillary matting material
In short, the instructions to make your own capillary mat setup are:
- Lay down a clean poly sheet
- Lay the fibrous capillary matting material on top of the film
- Place plants on capillary matting in locations where the plant will be in contact with the capillary material
- Expose capillary mat to water to enable the mat to supply water to the plants.
And voila! Anyone can make a capillary mat. However, the mat might not always be successful. It’s important to pick materials that are absorbent but will also last awhile.
One downside to greenhouses is that many of the products inside are susceptible to mold, mildew, and unpleasant bacterial growths. These create bad odors and can harm the health of humans and plants alike. For further discussion on capillary mat materials, see below.
Just be aware that water can escape from the rudimentary capillary mat if the fibrous material is not good enough.
Placing a Border or Rim
With all this in mind, DIY individuals should consider building some sort of border or rim. The easiest ones to make come from cardboard that is biodegradable.
Like any basic arts and crafts product, all the DIY person has to do is cut out a square or rectangle slightly larger than the mat and place it around the capillary. This will help prevent too much water from running off. For best results, individuals should cover the cardboard in a plastic film to improve its water resistance.
Adding a Top Sheet
Some gardeners like to use an additional poly sheet on the top of the fibrous material, which will sit above the capillary mat, and also above the rim, to ensure it’s all waterproof.
Should you want to add another layer of plastic sheeting, simply cut holes in the plastic in the locations where you place your plants, so that they will be in contact with the matting, and not the plastic top sheet.
The Best Capillary Mat Materials
Horticulturist Ken Sanderson developed an inexpensive, successful capillary mat while working at a greenhouse at the Alabama Agricultural Experiment Station at Auburn University. He wished to figure out whether a homemade mat would be successful, and just what kind of materials it would entail. His work earned him the Green Thumbs Up award from the McGreen Wisdom Project because the results could be replicated by any DIY homeowner around the world.
He found that using newspaper is an effective, simple, inexpensive solution!
So, what does his method entail?
An individual will need two basic materials: non-porous but flexible black plastic sheeting and a ton of newspaper. First, the plastic needs to be laid flat on the greenhouse table, bench, or whatever surface plants and their pots will sit on in your backyard greenhouse.
Then, cover the plastic with a layer of newspaper that is 8-10 sheets thick. Unfolded newspapers work best. Plants can then be placed on top of the makeshift capillary mat with ease.
This form of DIY mat has two obvious benefits. First, it is inexpensive. Newspaper is pretty easy to source in your recycle bin!
Second, this particular design avoids the mold, mildew, and fungus that plagues other DIY mats.
Because the newspaper is exposed to the open air, there is less darkness in which these growths can develop. This spares greenhouse owners from nasty smells and potential dangers to their plants.
Of course, there are numerous materials you can use for capillary matting. Many like felt, or other pre-made capillary matting materials specifically designed to work in greenhouses. If you want to go in this direction, that makes sense to us.
Last update on 2021-05-14 / Affiliate links / Images from Amazon Product Advertising API
If you want to use newspaper, that’s great too!
Just be aware that you can’t use a bucket or reservoir watering system if you go with newspaper as your matting material.
Pre-Made Greenhouse Capillary Mat Setups
Some may want to try out premade setups, which remove some of the headaches of setting up the DIY system. If you want to go with pre-configured trays, check out these Self-Watering Trays by Gardener’s Supply.
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This setup consists of a plastic tray, with a rim already in place. A water reservoir is on the bottom. The capillary mat is placed partially in the water reservoir. Plants are placed on the mat, and take up water as needed.
Providing Water to Your Capillary Mat Setups
Once you’ve got your capillary mat setups in place, you can provide water to your plants in a few different ways, all of which are super convenient.
Buckets and Reservoirs
One easy way to get water to your mat is to place one end of the mat in a bucket of water, or another vessel for water. The bucket can be placed below the mat (within reason) and water will flow up to the plants as needed. The mat will wick the water up to the plants.
You could use an automatic hose timer to easily refill your buckets periodically.
Keep in mind if you use the newspaper method, this style of water-sourcing likely won’t work.
DIY Irrigation System Directly on Mat
You could use a DIY garden irrigation system, and set up the water spouts so that they pour water directly on the capillary material at regular intervals. This can be effective with newspaper-style mats, as water is going directly on the flat mat material.
DIY Irrigation System into Reservoir or Bucket
You could also set up your irrigation system so that it fills the reservoir, or bucket, at regular intervals. This is a little bit easier to set up than filling individual mats, as you’ll probably have less pipe to run and can fill a bucket or vessel with several days or weeks of water.
Capillary mats are a great solution for automated watering in a greenhouse or polytunnel greenhouse. These setups will help eliminate drudgery and help you systematize your gardening process.
Should you decide to go with the newspaper solution, you can create capillary mats extremely cheaply, but you likely won’t be able to use a bucket or reservoir for watering. You’ll need some other sort of automated water system to soak the mats (or just wet them yourself, regularly!)
If you want to spend the extra money on felt mats, or use commercially-available capillary matting, you can use buckets or reservoirs, or a DIY irrigation system, and create a super-power, flexible, easy to use greenhouse watering system that will get your plants growing quickly and healthily.