Grow box

Grow box: grow hot peppers indoors

Grow box, the hot pepper is particularly exciting cultivation and can give enormous satisfaction. However, it is a demanding species in terms of climate, so it can be challenging to cultivate it in northern Italy. Fortunately, there is the possibility of creating a protected environment, in which our chili can grow without worrying about the cold outside, this “box” with lighting and heating is called a grow box.

Let’s find out when it is convenient to grow indoors and what are the most important characteristics that the “box” that will host our very spicy vegetables must-have. We will focus on the aspects related to the grow boxes, such as light, ventilation, and temperature. However, other aspects that are important for growing chilies (container, soil, fertilization, cultivation techniques,…) will be explored in other articles.

How to sow hot peppers. Let’s find out the technique and the period suitable for sowing hot peppers. FIND OUT MORE

What is the grow box for?

There are many types of hot peppers, from the classic cayenne to the dreaded Carolina Reaper, they have different shapes, colors, and above all scores on the Scoville scale, which precisely measures spiciness. Many of these varieties have tropical origins, for example, the Mexican jalapeno or the Cuban habanero, and require very hot climates. They don’t always feel good in our climate, especially for those who grow in northern Italy.

During the summer there are no problems growing chilies outdoors throughout Italy, but the spring months can turn out to be too cold. The pepper plant suffers if the temperature drops below 16 degrees, a late-night frost may be enough to irreversibly compromise the growth of our pepper.

Chillies have rather long cultivation cycles: from sowing they take 5-6 months to form a satisfactory harvest, hot chili peppers are rather slow in ripening and need a lot of suns. For this reason, it is not always possible to wait for the outside temperature to rise to sow, it is necessary to anticipate sowing and find a way to protect the plant until the climate allows transplanting. This is exactly where the to grow box comes into play.

If we live in an area where we have 3-4 months in a sufficiently warm climate and we want to grow a pepper that requires 6 months of cultivation cycle, it is necessary to be able to keep the plants for 2-3 months in an artificial climate. Those who cultivate the vegetable garden will be accustomed to sowing in seedbeds during the winter months, in order to arrive in spring with seedlings ready to be placed in the field. In the case of chili, however, it might be appropriate to keep the plant for a longer time in a sheltered environment. The classic seedbed is not suitable for size and characteristics for grown plants. The seeds to germinate are satisfied with little, but for a developed plant you need more care. This is why it is advisable to prepare a grow box equipped with all the comforts, where temperature, humidity, ventilation, and lighting are optimal.

How much to keep chilli plants indoors

A well-made grow box can accompany a pepper plant from birth to all stages of its life and therefore produce fruit directly indoors. This is not what I recommend, even if it can be a solution for those who do not have land or even a sunny balcony and therefore have no other option than to cultivate in an artificial environment.

In my opinion, the idea is to use the grow box for the growth phase and as soon as possible to move the plant into the field.

Indoor cultivation is however more demanding since it requires electricity for lighting, heating, and ventilation. It becomes anti-economic and anti-ecological to do so when outside the sun can do everything for free. Even the irrigation and fertilization requirements that a potted plant needs are higher than in the open ground, where the chili pepper has the possibility to expand its roots and partially autonomously find water and nutrients. Furthermore, the period of flowering and fruit ripening complicates things a little, with greater demands on the type of light.

We can start growing from the seedbed: for the first days of the plant’s life you don’t need to mobilize a grow box, it would be oversized. The seeds can then be germinated in a small seedbed, less bulky and easier to heat. A small locker is an excellent solution. This economical and ventilated model holds 60 jars, it can be an excellent choice.

When the seedlings are now developed, we can replenish them in a larger pot and transfer them to the grow box.

How a grow box should be made

The grow box can be self-produced, for those with a passion for DIY it is a question of building a box accessible from the inside, to which to apply the various elements (lamps, ventilation, heating,…) that can be safely purchased separately. Of course, it is not easy to make a DIY grow box correctly, which has the right materials, is solid, illuminated, ventilated, and heated in the right way.

Fortunately, for those who do not have the time and desire to get to work, there are also complete grow boxes on the market, with an investment of 50/200 euros, depending on the characteristics, you can get the ideal product.

Below we see all the features necessary for a good environment for indoor cultivation, they can be useful tips both for building a DIY grow box and for understanding how to choose which product to buy.


The size is the first point to be defined for our grow box: we can make a mini grow box, a little more than a seedbed if we plan to keep the peppers indoors for a short time and therefore the plants will still be small. Let us remember that each plant grows both as an aerial part and as a root system, so as the plant grows, the size of the pot in which we must keep it also increases.

  • The height measurement of a good pepper growbox should be at least 80/90 cm, in which you can easily grow plants of 30 cm in height indoors.
  • The measure of width and depth instead depends on how many plants we want to keep at the same time. A mini grow box in this could be 40 x 40cm, for a small production of spicy plants 100 x 50cm can be a good size.
  • If in doubt, we can build or buy a slightly larger structure than what we think it will serve, but without exaggerating. Let’s not forget that heating a larger volume grow box involves more energy.


The walls of our indoor growing box must be solid and must properly insulate the interior. This allows not to dissipate the heating unnecessarily, maintaining the internal temperature.

Often the grow boxes that are on the market are made not with completely rigid structures but with special materials that allow a tent-like opening, in fact, they are called grow tends. This is a very practical system, it is important that at least two sides are accessible.

Inside our box it is important that the walls are coated with reflective material, the most used professionally is Mylar, in DIY solutions you can use aluminum paper, even if it breaks easily, so it is a short-term solution.

Temperature and heating

Temperature, together with humidity, is the first important condition for the plant and is necessary from the beginning of cultivation, to germinate the seeds.

Chilies are ideally born at 25 degrees and a climate between 20 and 30 degrees is optimal for the entire cultivation. Indoors we can heat in various ways, generally, a heating cable is used to put at the base, powered by electricity. Alternatively, there are also grow box heater tubes, which radiate heat with discreet uniformity.

Many ready-made grow boxes have an integrated heating system. If we keep the grow box in a heated room we can also decide that the heating of the house does the bulk of the work. Be careful, however, that the warmth necessary for our peppers always remains inside the box. You can choose to differentiate day and night even in the climate, but we must never go below 20 degrees in any case.

Of course, we need an internal thermometer. Since humidity is another important factor, it is better to choose a Thermo hygrometer. or we can buy a heating cable already included with a thermostat with the probe so that the regulation is autonomous. This depends on whether we want to control the temperature by activating the heating or if we plan to do so by throwing out hot air as needed and ventilating.

Irrigation and nutrition

Water is an important source of life for plants, we must also guarantee it indoors if we want to grow chilies.

The water we use to wet the chili plants must be controlled: using only tap water if it is too calcareous can become a problem for the plant, interfering with its ability to absorb nutritional microelements. Furthermore, chlorine is often used in the water supply to disinfect.

Chlorine is volatile: let the water for irrigation settle for at least 24 hours. Then we check the ph value, very simple to measure (there are also special meters) and we verify that it is correct (value around 6).

The potted plant must also be fed: in a vegetable garden, we can fertilize richly before planting, with basic fertilization based on compost and manure. A few sporadic additions are enough during cultivation. Growing in a small container, on the other hand, fertilization must be more frequent, because the soil in the pot is too little to hold a supply of nourishment. Fertigation is often used, it may also be worth considering specific products.

In the case of liquid fertilization, it is worth checking the EC (electrical conductivity) of the water and fertilizer solution, because this is related to the salts dissolved in the water and must not be too high. Verification is feasible with a special tool: the conductivity meter, quite cheap to buy. An EC greater than 2.8 means that you have overdone the fertilizer in the solution.

Internal humidity and ventilation

However, the humidity level deserves special attention because we are in a closed place. Stagnant humidity is a situation to be absolutely avoided because it favors the onset of lethal diseases for plants. We then set up a hygrometer with the probe in our grow box to measure humidity.

Air recirculation is essential and we must therefore have an adequate ventilation system for the internal volume. The fan must not blow directly on the aerial part of the plant or on the soil, to prevent it from favoring transpiration too much. Obviously, you need a hole from which the moisture can escape and possibly an extractor, since it is hot air it is better to arrange it at the top.

We can also choose to automate the humidity control, by inserting a monitoring unit, able to activate the extractor and fan as needed. This allows keeping the humidity and temperature of the environment constant.

Lighting: fluorescent, neon or led

As everyone knows, plants need light, which is essential for chlorophyll photosynthesis and flowering. If the seed germinates without problem in the dark, as soon as the seedling releases its leaves it must find the right lighting. In indoor cultivation, it will obviously not be provided by the sun and it is our job to provide suitable lights in the grow box. Not all lights are the same, for chilies to grow well they need a color gradation of around 6500k, which is a cold light. The first check to do when purchasing the lamps is that they show this value.

Respected this parameter we can choose the type of lamp as desired: it can be the usual fluorescent lamp, neon tubes, or more modern LEDs. From the point of view of consumption, it is clear that low-consumption LEDs and neon lights are to be preferred. A classic bulb also generates the light in a timely and therefore less uniform way, while for example, the neon lights arranged along the entire length of our grow box can give balanced light over the entire surface. The grow-specific red and blue led is probably the best choice, but neons are cheaper and work well anyway.

The light requirements of a plant vary in its different stages of growth. Blue light is important for photosynthesis, while red is for the flowering phase. For this reason, there are lamps specifically indicated for flowering plants, but if we plan to remove the peppers and transfer them to the vegetable garden, it will not be necessary to obtain them.

In order to simulate the natural day even inside the grow box, it is necessary to give a day phase (lights on) and a night phase (lights off). This does not mean having to turn the lights on and off every day, a timed socket will suffice to do it automatically. 18 hours a day of light can be a good time during growth, in the eventual flowering phase 12 is sufficient.

Complete kit for indoor pepper cultivation

Those who are beginners should not be frightened by what they have read so far: if building a DIY grow box requires a lot of attention, luckily it is also possible to buy a pre-made kit for indoor cultivation.

There are many proposals on the market, I would like to point out a kit that is designed specifically for chillies and allows you to grow hot pepper plants 20/25 cm tall indoors.

In addition to the correctly sized grow tent, equipped with air circulation, the kit also includes suitable neon lighting, thermo-hygrometer for monitoring, timer, and even soil and fertilizer specific for hot peppers.

How to grow chillies. The complete guide to the cultivation of chillies: from sowing to harvesting, through the organic prevention of insects and diseases. FIND OUT MORE

You may be interested to read about the Hot peppers: grow guide/ Habanero pepper blogpost/ Calabrian chilli blogpost/ Jalapeño pepper blogpost/ Naga morich pepper blogpost/ Carolina reaper blogpost/ Bhut jolokia blogpost/ lamb rice recipe.

Leave a Comment

Your email address will not be published.