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How To Grow Cactus Seeds Guide

Step by step guide for beginners

Cactus seedlings a few years old ready for sale

Growing cactus from seeds is not only very easy, it’s also incredibly rewarding to see an amazing cactus when it started out so tiny!

In this guide we are going to show you all the basic steps, materials, environment, tips and tricks needed to get your cactus growing from seed (without getting too technical).

If you’re after the more in depth version or plan on growing with lights etc, check out our Advanced Seed Growing Guide instead.

1) Materials

cactus in pot

The first thing to consider when trying to grow cactus from seed is all the material & supplies needed to do it.

For the purpose of this guide being for beginners, we are going to keep the materials used cost effective and easy to find, you probably already have them at home.

In order to grow cacti from seeds you will need-

  1. Cactus Seeds- At least 10x seeds but more is better.
  2. Light- A very sunny (in-direct) location with minimum 6+ hours of great sunlight each day (10+ is better).
  3. Water Spray Bottle- This is to wet the soil without drenching it or disturbing the seeds.
  4. Tray/Container- A clear container with a lid is perfect. If not, a growers tray works great with glad/cling wrap as a lid.
  5. Soil Mix- You can use cacti/succulent pre mixes or make a DIY mix (1/3 soil, 1/3 pearlite & 1/3 river sand)

2) Preparation Steps

Before actually sewing (planting) your cactus seeds, there is a few things to consider to give you the best possible chance at success-

  1. The Location- Possibly the most important factor in growing cacti from seeds. Pick a spot like a window sill that gets indirect light all day but not direct sunlight (this burns the seedlings). It’s a good idea to use a table bench to allow the seed container to sit half a metre back from the window to avoid glare burning off the glass.
  2. Clean Materials– In order to improve germination rates for the seeds, ensure everything is nice and clean. Use regular dish soap or 70% alcohol wipes to clean containers, utensils etc. This is not essentially but will definitely increase your success rate.
  3. Clean Soil- This is also not compulsory but a good idea to “sterilise” the soil. Simply add your mix to a microwave friendly container and microwave on high for 1.5minutes (allow to cool before using).
 
PRO TIP: Plan ahead, best to leave the seeds in this location for at least 6 months to avoid shock in a new location.

Problems-

  1. Too much direct sun light and your seedlings with turn red/purple and die.
  2. Too little light will not met the requirements for the cactus seeds to get started (germinate), they will likely do nothing and wait for the right conditions.
 
2) Once you’ve selected where the seeds will be left to germinate, it’s time to select what container they will grow in.

3) Sewing the seeds

Cactus seeds Myrtillocactus Geometrizans, also known as blue myrtle cactus
Myrtillocactus Geometrizans Seeds (Blue Candle Cactus)

Once all your prep work is done you are ready to get started.

  1. Add the soil to the container/tray but remember to leave at least 1 inch gap between the soil and the lid (this is to avoid them hitting the lid before ready to come out)
  2. Gently pat the soil down flat (so the seeds don’t fall down a hole and get light easily)
  3. Sprinkle the seeds evenly over the soil
  4. Very gently pat the soil & seeds again so they are semi in the soil but still above it to get light.
Optional Extra Step
  1. Sprinkle a fine layer of sterile river sand on top (reduces the chance of fungus)

4)Germination Questions

What is germination? 

Germination is what we are trying to achieve when growing cactus. What it basically means is the process the seeds go through when they change from dry seeds and sprout into a very small green growth.

How Long Does Cactus Seed Germination Take?

Cactus seeds generally germinate within a few weeks but depending on the conditions, age of seed and much more, it can take months for the seeds to germinate.

What is a good percentage of germination for cactus seeds?

Generally speaking, 60-80% germination rate in cactus is considered normal and 80%+ is good. Germination rate depends on a huge amount of factors though down to the type of cactus, amount of sunlight, moisture, age, soil & air temperature + much more. Some seeds even require freezing first to germinate properly so germination rate will vary lots.

Common Mistakes

Common mistakes when growing cactus from seeds is something we all have when starting out. Here is the most common ones with ways to fix it-

  1. White fuzz in your container- The most common killer of cactus seeds after germination is white mold. This white fuzzy fungus (mold) will grow on your baby cactus and most likely kill it. It’s very common and happens to the best of us! This is because inside the container it has high humidity and no air circulation. To get rid of the white fungus, either scoop out the seedling and top soil with the fungus and hope it doesn’t spread further, or water the soil with a mixture of hydrogen peroxide & water (3% hydrogen peroxide 15ml mixed with 250ml of water).
  2.  Green Algae- This is also very common when growing cacti from seeds as it has all the damp conditions needed for algae to grow. Don’t be alarmed as this is normal and unless it gets very thick and stops the sunlight on the seedlings it usually remains harmless. If it grows too much, allow some air flow to reduce it’s growth or more direct sunlight (be aware both can kill fresh seedlings but it’s a trade off).
  3. Too Wet- If your seeds don’t germinate it may be due to the soil be far too soggy. You want it to be moist, but not absolutely drenched with water sitting on top.
  4. Too Dry– If there isn’t enough moisture in the container for a long enough period of time, the seeds may not germinate and remain dormant waiting for the right conditions. If this happens, wet the soil more and give it a bit longer.
  5. Seedlings red or purple- When your new seedlings turn red or purple it means they are getting too much intense light. If using a window sill either pull the seedlings further away or add a shade cloth (20-30%) over the container to help filter the light more.

FAQ

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How fast your cactus seeds grow depends on many factors from the type of cactus & it’s environment. Generally you will get a few cms in the first year or 2. Some types (genus) do grow much faster than others.

While in their sealed container, cactus seedlings generally don’t need watering unless they dry out.

Once out of their containers, cactus seedlings will need more regular watering than adults. Once your seedlings are in open air, it’s important to monitor the moisture levels of the soil.

Generally once a week a light spray works good but this will vary greatly for everyone depending on where you live and conditions.

If in doubt, use a moisture meter to check the moisture level on your soil. 

How long you leave the cactus seedings in their sealed container is up to you but as a general rule it’s best to leave them in for at least 3 months before allowing them open air.

The benefits of leaving cactus seedlings in a sealed and moist container is you don’t need to water them or worry about them drying out. 

Here at Mr Prick we try leave them sealed for 6-8months before letting them out gradually with fresh air increments over time.

There is plenty of places you can buy cactus seeds including online from us.

The main things to consider is:-

A) Do they clean the seeds properly? We use a hydrogen peroxide mix to clean our seeds and make them sterile which reduces the chance of fungus.

B) Are they mixed with something else? We hand pollinate most of our cactus to give the best chance of accurate seeds and almost eliminate the chance of cross pollination.

Need More Help?

As a cactus/succulent specialist store we do cater for almost all your growing needs. If you have questions or need further info, reach out to our cacti nerds at info@mrprick.com.au or follow us on instagram and send a message!

Ready for more in depth info? Check out our Advanced Cactus Seed Guide with grow light tips and tricks.