Should I Start Cannabis Seeds Indoors for Outdoor Growing?

When I first started growing cannabis outdoors (in New York City) I planted seeds directly in the soil the first week or so of May.  I was not very experienced, and starting plants outdoors was not always reliable, I ran in to problems.   Starting cannabis seeds indoors and moving them outdoors has provided the best results.  I start my cannabis and vegetables indoors every season and always have good results.

You should start cannabis seeds indoors, grown them for 1-3 weeks indoors then move your plants outdoors.  This gives you the best opportunity to keep your plants healthy, safe, and vigorous.  Basically, a great head start on the growing season.

We will now review all the important points that contribute to a successful indoor start and how to move your plants outside to their final location.  This overview applies to all types of cannabis including photoperiod and autoflower strains.  Here is an outline of what will be covered:

  • Why Start Cannabis Indoors if You Are Growing Outdoors
  • Materials You Will Need to Start Your Cannabis Indoors
  • How Many Cannabis Plants to Start Indoors
  • When to Germinate Your Cannabis Seeds for Outdoor Season
  • How Long to Grow Cannabis Indoors Before Moving Outdoors
  • How to Transplant Cannabis to the Outdoor Location

Why Start Cannabis Indoors if You Are Growing Outdoors?

In general, growing indoors provides a very consistent controllable environment.  You control the light, temperature, air flow, humidity and nutrient schedule.  A perfect sunny day every day!

When growing plants outdoors you can not control any of the environmental factors.  This is not a major issue as plants have grown ok forever without human intervention but there are benefits to starting indoors:     

  • Better conditions indoors
  • Can start growing while spring temperatures start to warm up

There is a big difference between “Growing cannabis indoors” for the plant’s entire life and simply “Starting cannabis indoors” to give your outdoor bound plants a good head start on the season.  To start cannabis indoors we do not need a sophisticated setup.  Let’s keep that in mind for the duration of this outline.

Materials You Will Need to Start Your Cannabis Indoors

Recommended Materials:

  • Basic budget grow light
  • Timer to control grow light
  • Soil
  • Cannabis seed(s)
  • Small grow container(s)

We are only starting the plants indoors so a sophisticated setup is not required.  Here is an example of materials and their cost:

MaterialExample Cost
2 Foot Fluorescent Grow LampClick here to view on Amazon$36
SoilClick here to view on Amazon$23
Containers to Start SeedsClick here to view on Amazon$14
Timer to Control Grow LampClick here to view on Amazon$9
SeedsClick here to view Nirvana seed seller$20-$40 for 5 seeds

The goal of this setup is to start and grow your cannabis for 2-3 weeks indoors then transplant them outside.  While there is a cost associated with these materials you can reuse the light, containers and timer every season. 

This setup will support starting 5 plants Indoors.  If you would like to support staring 10 plants indoors simply choose a 4 foot fluorescent grow lamp instead of the 2 foot version outlined above.

If you are not certain that you will grow every year then as an alternative to these materials, find a sunny windowsill to provide the light and just purchase soil, containers and seed.  This will reduce the cost but if you decide to grow every season then invest in these materials.

I use a simple setup with a 4 foot (4 bulb) fluorescent fixture.  Check it out here on YouTube. I start all my outdoor grows under this setup.

How Many Cannabis Plants to Start Indoors

Deciding how many plants to start indoors is directly related to how many plants you desire to grow outside.  In general, start 1-2 more plants than the total number of plants you want to eventually grow in total.

For example, if you want to grow 3 plants outdoors then start 4-5 indoors.  Just in case you run in to any issues that damage, stunt or kill the plants you have extras just in case.  If all your plants grow perfectly than you simply discard the ones you do not want (Take the best 3 of the bunch when you are ready to move them outdoors)

This “Deciding” process will also determine how many seeds to buy.  Cannabis seeds are not cheap when compared to vegetables for example.  In general, cannabis seeds for small hobby growers can be purchased in combinations ranging from 1-10 seeds and costing from $5-$10 for each seed.  Prices will vary but the point is that Cannabis seeds cost more than vegetable seeds.

Another factor to consider is the time it takes to have your seeds shipped.  It can take between 14-30 days for your seeds to get delivered after the purchase.  You need to take this into consideration because timing of your seed purchase directly effects your ability to start growing indoors.  You can’t start your grow indoors without seeds!

When to Germinate Your Cannabis Seeds for Outdoor Season

Starting indoors at the beginning of spring is useful in creating a fast-growing healthy plant that will not be exposed to “tricky” early spring weather.  I typically germinate my cannabis seeds indoors the 3rd week of April.

Just because winter is over and spring is here does not mean that the temperature is optimal for cannabis growing. There are plenty of “unusually cold” days and “inclement weather” that could jeopardize your plants survival.  To avoid this issue, start your plants indoors.  It is a great insurance plan.

Here in New York City the temperatures seem just about right on May 15th for me to move my plants outdoors.  My target every year is usually mid May.

In order for me to meet this target date:

  • I purchased my seeds the first week of March
  • Received my seeds (14 days later) – The 3rd week of March
  • Germinated my seeds one month later – The 3rd Week of April
  • Plants were well established – 6 inches tall and very healthy – Ready to be moved outdoors Mid May

How Long to Grow Cannabis Indoors Before Moving Outdoors

The overall goal to staring cannabis plants indoors is to provide a “Head start” prior to moving them outdoors. So, grow your plants indoors for 3-4 weeks then transplant them outdoors.

In the first 3-4 weeks of a plant’s life, they will usually not grow into huge plants. This means you can use a small amount of space indoors to support your plants during this time period.

Most likely you will not need to feed your plants because the soil should have enough nutrition to sustain the plant.  If your plants start to look hungry you can certainly feed them.  I grow organically and would recommend feeding your plants organically too. 

For a basic liquid vegetative food check out “Nature’s Source Plant Food”.  1 Teaspoon mixed in 1 gallon of water and feed every 7-14 days.  Discard the remainder of unused solution after each feeding.  Feed with fresh solution each time.  At this rate, if you feed at all you will only feed 1 -2 times MAXIUMUM. 

Natures Source fertilizer from Amazon Website

The biggest mistake beginners often make is feeding and watering too much.   

You will most likely need to water more than you feed.  Your plants will not grow very large during this time indoors and therefore will not be drinking a lot either.  However, depending on how dry or humid your grow area is, the soil will eventually dry out and need to be watered.  You want to keep the soil moist and not overly wet.

With my conditions I water every 3-5 days.  Soil should be moist and not sopping wet.  You do not want to overwater your plants as this will stunt their growth and possibly kill them.  If you have never grown in soil before then the best indicator of how wet to keep you soil is:


  • Pay attention to how your soil looks and feels fresh out of the bag.   Keep soil slightly more wet compared to when the soil came out of the bag.  This is generalization but a good estimate
  • Pay attention to how heavy your container feels after you prepare them with soil for the first time.  Lift the container with one hand and pay attention to how heavy it feels. Every day lift the container and pay attention to the weight.  Once the container feels ½ as heavy than it originally did then it is time to water again.

You can also use a moisture meter to gauge moister.  A cheap one will do, one like this found on amazon:

Moisture Meter From Amazon Website   

How to Transplant Cannabis to the Outdoor Location

First determine if your plants are ready to move outside.  We discussed earlier that our estimate is 3-4 weeks of indoor growing then it’s time to move outside.  While this is a good range of time you need to choose the most appropriate time for you.  Here are some indicators of when to move plants outside

  When you are ready to move your plants outdoors:

  • If your plants grow very fast then you may be able to move them earlier.  If your plants have grown as tall as the container they live in, then it is a perfect time to move them outside
  • If you are going out of town on vacation for example, then you can certainly move them outside earlier.  You are looking for a good “head start” for the plant.  You do not have to do everything according to an exact schedule
  • If your plants are not as tall as the container they are growing in and you have reached the 3-4 week mark then it probably makes sense to move them outside anyway

To transplant follow these steps:

  • Take the plants to their outdoor location
  • Use a small shovel or your hands to make a hole the size of the plant container in the spot where you are transplanting to
  • Take your hand and place over the top of the container that contains the plant.  Put the stem of the plant in between your finger and rest your palm on top of the container
  • With your first hand on the container as described in the previous step, now use your free hand to gently squeeze the bottom of the container.  Gently squeeze and rotate the container.  Repeat this process until you have rotated the container 1 full time.  This will loosen the soil just in case it is sticking to the side of the container
  • With your first hand still covering the top of the container now turn the plant upside (your first hand will be used to keep the plant from falling out of the container too quickly).  The soil should be loose enough, and the plant should easily slide out of the container
  • Place the plant in the new hole
  • Press the plant gently into the hole you created
  • Water area to moisten soil in new hole

One last thing to mention about transplanting is a difference between photoperiod and autoflower cannabis. These differences are related specifically to timing with transplanting.

 Autoflower cannabis will grow for around 1 month and then start to fruit automatically.  Photoperiod cannabis will continue to grow and ONLY begin flowering when the plant detects that the days are getting shorter.  Flowering happens outdoors for photoperiod at the ends of the season as the days become shorter. 

When transplanting photoperiod plants outdoors at the beginning of the season, timing is not extremely critical.  For autoflowering cannabis however, you want to make sure the plant has not become rootbound and you transplant before the plants starts to fruit\flower.

Rootbound plants when transplanted need a week or so to adjust to the new container.  This is not a big deal with photoperiod plants because they will just grow more slowly for a week after they are transplanted and will have plenty of time to recover.  Autoflower plants only grow for 60-100 days so you want to make sure you do not delay their growth because they do not have much time to grow and fruit\flower.

Rootbound plants just mean that you let the plant grow too large for the container.  This stunts the growth:

Rootbound roots look like this:

Non-Rootbound roots look like:

In conlcuion, there are plenty of benefits to starting your cannabis indoors and then moving them outoors.  There is a cost assocaited with these materials but you can reuse the tools every season and get a good start to the season.

One last thing I would like to mention is that this setup is especially useful to growing multiple  rounds of autoflowering cannabis outside.  In New York City I can grow from May to October so I can grow 2 rounds of autoflowers:

Round 1 = May to July

Round 2 = August-October

If I only have room for 5 plants outdoors then having the abilty to start them indoors gives me a lot of flexibility to plan my grow!

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