You can grow cactus plants from seeds, even here in the UK! By sterilising your seed sowing compost and mixing 50:50 with perlite and adding to your domed propagator. Scatter the cactus seeds on the soil, distributing evenly. Thinly sprinkle vermiculite on top, spray generously with dechlorinated water and cover with a lid or cling film. Place on a heat mat under gentle light.
How to Sterilise Potting Soil
Sterilise your soil by one of the following methods; Steaming (with/without pressure cooker), heating (oven/microwave). Alternatively you could use chemical sterilisation.
Spread the soil thinly in a tray and spray with hydrogen peroxide 3% solution (e.g. Half a cup of Hydrogen peroxide to One gallon of water). Allow the treatment to work its magic for 3-4 hours, this will ensure all harmful spores are destroyed.
Prepare Seed Sowing Mix
In a large bowl or tub, combine a cactus potting mix ratio of 50% seed sewing compost with 50% perlite. This will help to keep the soil moist, encouraging seeds to germinate with rapid growth.
Cactus Plants Container Varieties
Depending on the amount of cactus seeds you plan to sow, choose a shallow container which is wide enough to spread the seeds evenly. A seed sowing dome propagator works best! This will allow enough space for the seeds to evolve into seedlings and subsequently cactus plants. When the seedlings become mature cactus plants, they will benefit from a clay pot/ terracotta plant pot.
"Terracotta pots are the best choice when it comes to mature cactus plants! They have a porous nature, great for absorbing excess moisture from the cactus soil. This reduces the risk of plants getting root rot!"
How to Sow Cactus Seeds
Scatter the cactus seeds onto the potting soil, distributing evenly. Using a seed tray tamper (or back of a spoon) gently touch the top of the cactus seeds, be careful not to push the seeds into the soil! Gently sprinkle a very thin layer of vermiculite or fine sand on top of the soil. The aim of the top layer is not to cover the seeds, but to give support to the seedlings, so that they can anchor and grow upwards.
Spray the soil generously with dechlorinated water (e.g. rain water or mineral water). Place the seed sowing tray dome on top, with the vent closed. Alternatively if you do not have a dome, wrap the tub with clingfilm and do not pierce. Ideally you should place the tub on a heat mat, under a gentle light.
Cactus Seed Germination
Cactus seeds typically germinate within a few weeks. The fresher the seeds, the faster they will germinate and the higher the germination rate will be! Initially it is important to keep the container sealed, the moisture will condence and create a humid environment for the seedlings, without introducing them to external elements too early.
Slowly introduce the cactus seedlings to their new environment by opening the vent in stages or piercing the clingfilm a little bit at a time, over the forthcoming weeks. If you are using a tray with a dome, keep the lid on and just open the vent to prevent mould. This will help to prevent too much fluctuation, maintaining an optimum environment for the seedling to mature.
Prepare Well-Draining Succulent Or Cactus Soil mix
In a large bowl or tub, combine a potting mix ratio 60-70% organic materials (e.g.peat-free compost) and 30-40% inorganic matter (e.g. Perlite/ Lava rock / coarse sand/ River Sand/ Pumice/ crushed granite or Limestone).
How to Pot Cactus Seedlings
Choose a larger pot size, with drainage holes. Most cactus plants will thrive in acidic potting soil, with a PH between 5 - 6.5. Gently lever the bottom of your cactus seedling to loosen from the soil and repot in new potting mix, covering the cactus seedlings roots and gently firming the soil.
After you have repot your cactus seedling, place in a warm, well ventilated room, with bright but indirect sunlight.
Best Cactus Seedlings
We love growing San Pedro Cactus plants from seed! Also known as Trichocereus Pachanoi, it is one of the fastest growing desert cactus that makes it a superb indoor cactus. Growing up to 30cm per year! The San Pedro cactus is most active in the spring and summer. Well known for their giant white flowers that bloom at night, lasting only but a few days before wilting.
One of the most popular desert varieties rarely available in the UK...but can be found at Desert Plants Ltd .
Watering & Lighting Requirements For Cactus Seedlings
DO NOT WATER your newly potted seedling for a minimum of 5 days, to allow the roots to establish.
If your cactus seedlings are receiving a high amount of light (e.g. Summer sun or under an artificial light), you can water more regularly to stimulate energy production and promote growth.
As the seedlings become mature cactus plants, they will require less watering and be more tolerant to direct sun, extreme heat and periods of drought. Most desert cacti will go through a dormancy period in winter and require little to no water, depending on the species of cacti. A few notable exceptions would be indoor cacti, that continue to be subject to artificial light or species that are actively growing/blooming in the winter period such as the Christmas cactus plant.
How Often to Fertilise Cactus Plants
Cacti grow slowly and many people don't fertilise cactus plants, but they survive right!? They certainly do survive however; if you really want to see your desert cacti thrive, then fertilising at the right time with the amount is a key component in their care.
Most cactus plants will benefit from cactus or succulent fertiliser (AKA plant food) a minimum of once per year in Spring (March), as this is typically the start of the growing season. However, cactus plants (especially younger cactus plants) will thrive if also fertilised in Summer (June) and fall (September). This can easily be sourced from most garden centers.
How Cactus Grow
Cactus seedlings will require more care and nurturing than an older cactus plants. In the optimum environment, with warmth and a good source of lighting, your cactus plants will thrive when regularly watered and fertilised two to even three times per year!
As the cactus plants grow and become mature, they will flourish in direct sunlight and can be placed outdoors in Summer! Although the majority of outdoor cacti should not be subject to frost, so be sure to research your cactus plants species. Cactus plants can survive long periods of drought, but quickly succumb to root rot with over-watering.
Growing cactus plants: problem solving
If your cactus plants appear unhealthy or are becoming prone to disease, a small dose of cactus plants fertiliser to the soil will likely be key! However, if you suspect a disease or pest, it is imperative that you treat this problem quickly. Growing cactus plants takes time and patience, as the majority of desert plants grow slowly. For example, the Saguaro cactus is a slow-growing cacti that can take 200 years to reach its full height!
New blog coming soon. To include information/treatment of Mealybugs, Cochineal Insect, Red Spider Mites, Slugs and Snails, Aphids, Thrips. To also include information about Fungal rot, Root Rot, Pesticides and Insecticides.