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best temperature to sprout cannabis seeds

While many plants can be germinated in the ground, cannabis seeds are fragile enough that you should germinate them before planting.

The environment in which seeds germinate also plays a role in the outcome. While there are several different germination methods, each requires proper moisture, minimal handling, and warm springtime temperatures between 68-72 degrees Fahrenheit.

So, you’ve decided to grow your own cannabis plants. You purchased a pack of seeds, assembled cultivation materials, cleared a space in your garden, and are ready to grow your first cannabis crop . With everything in hand, it’s time to begin the very first step of cannabis cultivation : germinating seeds.

How do you germinate seeds indoors?

Soil is an easy, more natural method with which to germinate your cannabis seeds because the soil protects the fragile roots from any interference. Photo by: Gina Coleman/Weedmaps

Germination itself is a crucial aspect of cannabis cultivation. The seed germination process is the foundation of every marijuana plant, and steps can be taken to boost successful popping. For example, some cultivators improve germination attempts by soaking seeds in 1% hydrogen peroxide or a compost tea for 12 hours beforehand to kill any dangerous pests.

To germinate seeds this way, lay one paper towel on top of a countertop, place a few seeds, and cover them with a second paper towel.

Place the soil in a small pot and use your finger or a pencil to push a small hole in the dirt, a bit more than half an inch deep. Insert the seed into the hole and bury it with soil. From this point on, don’t touch your seed. The young plant is fragile and knows how to position itself in the soil bed.

Three fundamental principles will trigger that first small taproot to appear: warmth, moisture, and darkness. With the promise of moisture, a single root will take shape before slowly developing into the cannabis plant we know and love. In the right conditions, seeds will begin to develop within 12–36 hours of moisture being introduced to them.

There is, of course, a far simpler way to germinate seeds. Ideal for beginners, the feminized starter kit by Royal Queen Seeds has everything you need to kick-start your next cannabis project.

WHAT IS AN EXPECTED GERMINATION TIME?

Regardless of where you get your seeds from, it is best to give them a slight (and delicate) inspection before planting. Most of the time, all seeds will germinate; however, poor-quality seeds will produce a weaker plant. Unfortunately, that is something you will not find out until well into the vegetative and flowering stages.

If you don’t like the idea of pre-soaking your soil, you can use a spray to moisten the holes before you plant each seed. With enough moisture surrounding your seeds, you can still encourage a root to develop.

Arguably one of the least effective methods, but it is still viable. Incredibly simple to facilitate, beginner growers may opt to germinate their seeds in a glass of water. Half-fill a glass or bowl with water that is approximately 22°C (71°F).

This Indoor Grow Garden includes reusable trays that can grow the plants for a week until transplanting into a bigger pot. The trays sit beneath 2x2ft 24W fluorescent bulbs for healthy growth. This setup provides light & warmth, it also ensures that fresh air & average humidity levels prevent negative factors from disturbing germination. The lights are housed in the canopy of a sturdy aluminium stand that has an adjustable height (up to 38cm H from base) and a reflective hood to maximize usable light. There are many different models of fluorescent or CFL fixtures on the market to suit every taste and budget. Give seedlings maximum light to prevent stretching and support fast development. Use additional light from a window if available. For best results we recommend HPS lamps from the start. A 70-150W HPS lamp does not use more electricity than standard CFL lamps but provides much more lumens (light intensity). If you are growing with 250-600W HPS then you should germinate or put your seedlings under the lamp as soon as possible to ensure quick and vigorous growth.

Mandala Seeds places great emphasis on the quality of the seed stock. We guarantee that the seeds from all products are fresh and viable when they are dispatched to resellers and customers. Seeds harvested from each mother plant are checked for optimal germination rates before they are approved for sale! In large tests (1000 or more) our seeds achieve a germination rate of 99,6%. Our seed stock is refreshed every 6-12 months! Therefore seed vendors and customers can be certain to purchase and store viable seeds at any time.

As soon as the first pair of leaves grow on the seedlings transplant them into 14-16 cm/5,5-6,5” pots, so that they have sufficient space for their root development and nutrients. You can also choose larger containers if you are confident that you will not over-water. We recommend a 4-5L/1 gallon container for the first 4 weeks of growth and subsequent period of sexing under 12/12. Repot females into larger containers after sexing. See our SOIL GUIDE for info on container sizes.

What happens if one uses pre-germination methods?

Take 8-10 cm/3-4” (diameter) pots or a seedling tray and fill with quality potting soil. Press the soil slightly down and make a 1,5 cm/0,6” deep hole with a pencil or finger. Place the seed in a horizontal position in the hole (this is the easiest method). Fill the hole and gently tap down the soil. Use chlorine free water (preferably good mineral water without gas) with a pH of 6-6.5 to water the pots. The soil should be uniformly moist and properly watered, but not soggy or waterlogged. The pots or tray should also not stand in a tray filled with water. Use a spoon or small beaker to dosage properly if you are unsure and want to avoid accidentally overwatering the soil. Put the pots or tray at a warm location and ideally under lighting. Temperatures at 25°C/75°F or higher accelerate germination. Take care that the soil does not dry out and that the pots don’t stand in the cold (ie. at or under 21°C/70°F). Misting the soil surface with water spray is not effective. You should water the pots properly if the soil surface dries up. Within 3-7 days the seedlings should appear out of the soil. You can switch on your lamps during germination to provide warmth or when the first seedlings appear. Since they might also grow out of the soil during the night it's best to have lighting switched on 24 hrs.

Remember: cannabis is not an orchid! Fungal spores are everywhere: in the air, in substrates, . and they await the conditions to spread and attack organic substances such as seeds or the roots. Common fungal infections are pythium and fusarium. Young seedlings are also prone to such infections because their cell tissue is very soft. Over-watering and/or high humidity trigger such diseases like “damping off” which quickly kills seedlings.

Provide sufficient light. Seedlings require sufficient light (this applies to the strength and length of daylight or artificial light) and fresh air to grow. Switch on your lamp(s) as soon as the first seedlings appear at the latest. Seedlings should be moved directly under a HPS lamp if you have one. The more light your provide the better your plants can grow. Not all Mandala strains are suited for low light such as CFL lamps and fluorescents. Make sure you choose the right strain for your lights.

Heating mats should be avoided unless you need it in the wintertime. A dysfunctional heating mat, or a mistake in the temperature control, can easily boil the seeds or dry up the substrate and shrivel the freshly emerging seedling. Your pots/rockwool cubes should be placed in a space with ambient room temperature (ie. 24-26°C/75-78°F). In the winter use a small electric or gas heater to warm up your grow space. You can also switch on the HPS lamp and put the pots at a close distance underneath.