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A Complete Guide to Cannabis Seedling Care

Keeping marijuana happy and healthy depends on the care we give to the plant throughout its life cycle. This is especially important in the younger stages, when living conditions are more complicated. When marijuana is at this stage, the plants are called seedlings. Today, we will give you the complete guide to cannabis seedling care.

In today’s article, you will know what cannabis seedlings are and we will review the different ways to treat them. All with the aim of giving you the best theory for growing cannabis plants, especially in those delicate, early stages of their life. Taking care of seedlings from day 1 is the best guarantee for excellent cannabis harvests.

What are seedlings?

The seedling is the first stage of the marijuana life cycle, they appear when the seed is open and the plant manifests itself after being exposed to light and humidity, by breaking through the substrate. It is a phase that gives way to vegetative growth and lasts approximately 1 to 2 weeks.

First steps

When germination is successful, the seed wall break and allow the first sprout to emerge with the first 2 leaves of the plant, the cotyledons. At the other end of the sprout will be the root, which will grow very quickly both downwards and sideways, in this order.

These first 2 leaves mark the beginning of the seedling’s life. However, these leaves are dummy leaves, i.e. they are not the leaves that your marijuana plant will show. These leaves provide energy for the plant, a small dose of nutrients to live before receiving nutrients, water or light. This reserve of energy is used by the cannabis seedling to take its first steps.

After these first 2 dummied leaves, another 2 leaves will appear on the seedling, these will show the typical Cannabis leaf lobes. As soon as the plant continues to grow, more leaves will appear with more lobes.

Keeping your plants healthy during their seedling stage will ensure optimal vegetative growth, as protecting your cannabis seedlings is an investment in the future of your crop. Next, we continue with the types of care that Cannabis seedlings need to give rise to healthy and strong plants.

The Best Bio Growth Nutrients

The Best Bio Growth Nutrients

What care do cannabis seedlings need?

As well as giving them all the care they need, they must be protected from outside conditions, which can be hostile to young plants. It is best to keep the seedlings in a protected place, i.e. indoors. In addition, the seedlings need to have a plastic covering or a transparent bubble like a greenhouse. Let’s go step by step through each of the necessary care for cannabis seedlings.

Protecting the seedlings

First things first, seedlings need a protecting covering to counteract temperature changes and prevent insects from proliferating in the area. Seedlings are weak and need extra protection at all times. As they do not have a developed immune system, they are particularly susceptible to harmful insects. In addition, they are so small and weak that any change can kill them, rain, wind, a pet…


Often it is not necessary to buy a greenhouse, there are other solutions that are cheap and easy to make. For example, the simplest and cheapest greenhouse consists of cutting a transparent plastic bottle in half, recycling the upper half and using the lower half. Two or three small holes are made in it, and finally the bottle is placed over the marijuana seedling, so that it covers it completely. In the event of a drop in temperature, or a massive loss of humidity, the bottle will provide a microclimate and will withstand inclement weather for longer, as well as making it more difficult for insects and any other threat to enter.

Humidity for seedlings

But in addition to protection, seedlings need other important elements, such as water. This is the time in the plant’s life when it needs the higher humidity, always more than 75%. To do this, you can use a water spray and apply it gently when the seedlings are dry. Note, however, that you can only spray them with water when there is no direct light, i.e. late in the evening or early in the morning. This is because the seedling has no firm roots to give it nutrients, so it will be a great help in receiving both water, or water and nutrients.

How to water Cannabis seedlings

watering seedlings

One of the most common problems in growing marijuana is providing too much water. By over-watering the plant, oxygen does not penetrate the roots properly and you will see symptoms such as drooping leaves. This can be patched up, but it is not the best way to start a healthy and abundant marijuana crop. Always remember the golden rule, alternate periods of watering with periods of dry soil.

Pot size is a factor that can cause problems with overwatering, as seedlings absorb less water than adult marijuana. Therefore, having the seedling in a very large pot and watering as much as the pot can hold can cause the roots of the seedling to become totally oversaturated by the amount of water available, preventing them from being able to absorb it all.

How to Water Marijuana

How to Water Marijuana? The Watering Guide

To avoid this situation, the best thing to do is to use small pots, the right ones are those adapted to the size of the seedlings. Once they have grown enough, transplant them into a larger container. In this way, the watering limit is set by the pot and there is less risk of overwatering.

On the other hand, it is also not advisable to keep the seedling in pots or containers that are too small for too long. The roots will start to get tangled and this will prevent them from developing properly, with the space they need.

Another factor that can lead to overwatering is the drainage of the seedlings. If the seedling pot does not have an efficient drainage system, i.e. holes that allow excess water to drain away, the stored water will create a problem. But it is not just about having holes in the pot, the type of soil used plays a key factor. Clay-based soils, for example, retain a lot of water, so it is advisable to avoid this type of substrate if you want good drainage.

If using small pots, with good drainage holes and a spongy soil that drains well, you find that drainage is still not optimal, you can use clay loam mixed with the soil. The clay will help the roots to breathe, bringing more oxygen to the substrate, so the soil will be able to drain water properly and the plants will withstand excess moisture for longer.

Nutrients for Marijuana Seedlings

seedling arising

Seedlings get most of their nourishment from light and water, but the nutrients that can be added to water or soil will be of great help at this stage. Bio root stimulators in particular are the most suitable fertilisers for the first weeks of the seedlings.

The Best Organic Root Boosters

The Best Organic Root Boosters

During the first 2 weeks, the seedlings focus their energy on root development, so in addition to adding a root stimulator, the pH and Ec must be kept at the correct values, as control of these two values is vital for the nutrition and development of the seedlings.

From the third week onwards, we can start watering moderately with growth fertilisers. Nitrogen is the most suitable element, as it accelerates the vigorous growth of the plant and is essential for the plant to move into the vegetative growth phase.

Best temperature for seedlings

The optimum temperature for seedlings is 22 to 25 degrees Celsius. If you notice that the temperature is higher, try moving the lights away, so that the temperature should drop by 1 or 2 degrees. If the seedling experiences too much heat, the leaves will start to curl upwards in a canoe shape.

Best lighting for seedlings

The light needs of a seedling are small, and as it grows, they will need more and more. It does not make sense to give brutal amounts of light in the first two weeks, and it can be dangerous.

A cheap CFL bulb is more than enough for this stage, they can be placed almost next to the seedling and consume very little light. The photoperiod should be 18 hours of light and 6 hours of darkness. If HPS lamps are used, they should be kept far enough away so that the temperature of the plant does not rise above 25ºC.

If sunlight is used, you should take in mind that it can be too much, especially in the middle of the day. The recommendation is to use the early morning sunlight as well as the late afternoon sunlight, and once two or three days have passed, and the seedling is used to it, make use of all the sunlight hours. The sun should be given in the morning until 11:00 a.m., then it is removed and put back in the sun at 16:00 p.m.. In this way, we ensure that the midday light does not burn the seedlings.

Spiking, why do seedlings stretch?

problems with seedlings

Marijuana seedlings grow too tall because of environmental factors, mainly when the seedling does not get enough light, it tends to stretch in an attempt to reach more light, which is known as spiking. When this happens, the seedling stretches further in search of light, developing a structure that is unsuitable for growth, as the thin stem will not be able to support the weight of the plant and may break.

This is a bad start, as a plant that is too tall will give way under the weight of its structure, but there is a solution. One solution used by many growers to correct spiking is to bury part of the stem, so that it starts to develop roots in the area where it used to be a stem, although ideally it should never spike at all.

This has been all about the care of marijuana seedlings, we hope it has helped you to understand all the theory behind it. If you have any questions, please let us know, leave your comment at the bottom of the post. If you liked this article, I recommend you read Five home remedies for marijuana (molds and pests).

Five home remedies for marijuana

Images vía Leaflyco

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Author: Brais Nieto

Fundador de Experiencia Natural, creativo y emprendedor, diseñador, master en grower y marketing. Por una normalización de todas las plantas y sustancias primando pacientes y usuarios.

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A Complete Guide to Cannabis Seedling Care
A Complete Guide to Cannabis Seedling Care Find out what Cannabis seedlings are, all about seedlings in this complete guide to their characteristics and important care.
Cannabis Seeds

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