Large outdoor planters
Planters… When I talk about large outdoor planters, I mean almost like the one that says, any size, from a large custom-built planter to any stone, ceramic, metal, wood or plastic planter purchased in a physical or online Garden Center. So although in this tutorial we take a large custom-built planter as an example, the tips are valid for any size and material. If possible, I would only exclude very, very small planters, where the space for soil is so scarce, that it is better to take full advantage of it for the substrate, without taking too much care in drainage.
After buying our planter or building it expressly, it seems that the process of preparing it for planting is pure formality and that it does not deserve special attention. However, the secret for the plants you are going to plant later to develop with vitality and show off all their ornamental properties lies in nothing more and no less than the substrate from which they are going to feed and the proper preparation of the planters.
What size planters to use?
Well, it will depend on the what, the how and the why, so in each case you must study well and analyze the different factors that can influence the final decision. To give a general rule, always the bigger the better, that is, planters as large as possible, according to the space, budget or other factors that determine the particular situation of each garden or terrace.
The reason for this is that plants feed on the soil and spread their roots through it, so for the vast majority of plants, the more substrate the better. Keep in mind that in nature there are no planters, this has been invented by humans.
How to prepare planters for planting?
1- Drainage
You are already starting from a planter bought or built, ok?, so the first step is to take into account drainage.
Without proper drainage, water will accumulate in the planters, rotting the soil, roots, and killing plants quickly.
Any planter in which it is going to be planted directly needs some drainage holes. If you build a planter don’t forget to prepare these holes, and if you buy the planters make sure it has drainage holes. Sometimes planters don’t have these holes, no problem, you just have to make them with a drill carefully and that’s it. It is recommended that there are several in case one becomes clogged over time and it is not necessary that they are exaggeratedly large, the size of a thumb is enough, except for planters built to measure that can be larger.
2- Gravel
Once it is confirmed that you have drainage in your planters, the goal is for it to work, and that it does not clog over time due to the soil that will be compacted and the roots that will grow and seek to deepen or extend towards the drainage holes.
For drainage to work in planters you must place a small layer of gravel at the bottom of the planter, the thickness varies depending on the size of the planters, between 2 and 10 cm. I recommend that it be of the pebble type, although there is also a specific gravel for drainage. If it is very important to reduce the weight of the planters, you can use Arlita expanded clay. Volcanic gravel is very famous for this purpose, however I do not recommend it if the planting project is long-term, because volcanic gravel erodes or decomposes easily becoming soil over the years and can clog drainage holes.
When planters are very small, it’s best to make the most of all the space available for the substrate, so you can place a stone in each drainage hole to protect it. That it is an irregular stone that does not cover it. If you lay a stone flat, you are nullifying the drainage holes yourself.
One thing you have to think about, is that that water that is going to come out through the drainage holes, does not come out clean, and if the planters are on top of walls or walls they can stain them and cause problems due to humidity, so in that case, if the planters are large I recommend you to conduct the water to where you are interested by placing some pipes directly in the drainage holes of the planter, well sealed and with a slope so that water can flow through them. For small planters, you should consider placing some water collection trays (what in pots are the plates).
3- Mesh
It is not enough to place a layer of gravel, you must place a special plastic sheet just above the gravel to prevent the soil and roots from seeping through the pebbles over time and also clogging the drainage holes.
I usually use weed netting because it’s very resistant. You can also use the Geotextile Mesh if you wish. Both meshes are perforated so they allow water to pass through. Under no circumstances should you use a waterproof plastic sheet because it would nullify the drainage.
You can also use the mesh to permeabilize the planters. If, for example, the planters are made of terracotta, they can have stains or halos as a result of watering and humidity that make them ugly, and it is common in wooden planters to protect them a little. It simply consists of lining the planters with this mesh. If they are made of wood, the mesh can be stapled to the edges and corners for better placement.
4- Substrate
Once drainage is guaranteed, the most important thing is the substrate. The good development of the plants will depend on it, so I do not recommend that you save on this section. No matter how good and of excellent quality the plants you are going to plant are, if you do it in a poor or unsuitable substrate, the final result will be far from what you had imagined.
A good plant substrate, rich in organic matter, is best. Have a good mixture that allows drainage.
It is advisable to compact the soil well, since when it is placed it has fluffed up and over time it will compact and come down, leaving the planter lacking soil and the plants very low.
In large planters I recommend filling them to the limit, overflowing, because although at first it is very uncomfortable to water because soon the water comes out, with time the soil will go down and the planter will be perfect then with those 5-10 cm. of burr. For smaller planters, which have less soil depth, it is not necessary to fill them so high because the soil will not go down as much when compacted, and it is convenient that there is space later so that when watering them the water does not overflow.
5- Plants
And it’s time to plant. We’re not going to talk about what to plant now, because that goes a long way. Now rather comment that if we are dealing with small planters, it is better to fill them with soil only as far as the plants can be easily placed, and then with the plants already placed finish filling the planter with soil. However, if you are dealing with large planters, I recommend the opposite, fill the planters to the brim by compacting well and then plant the plants.
6- Watering
These planters are going to have to be watered. If you are not going to do it manually, you should install an automatic irrigation system, very useful because it will allow you not to worry about watering and take advantage of your time in other things, and also the plants will not die when you are on vacation. In most cases, it is enough to connect a battery-powered irrigation controller to a faucet and install a drip irrigation pipe. We will discuss this in another video tutorial.
What I do warn you about, if you have a custom-built planter, is that it is very common to forget to leave the tubes for irrigation or decorative lighting past, and then, when you fall into it, it is very cumbersome, so keep it in mind from the beginning!
7- Mulching
Basically, it consists of covering the surface of the planters with a layer, either organic such as pine bark, or inorganic such as pebbles. The benefits are not only decorative, but also maintain moisture, protect the soil from erosion and reduce the appearance of weeds. However, perhaps it only makes sense in planters that are not too small.