Going Potty
Growing with pots and soil is a great introduction to indoor gardening; it's a cheap way to get started, soil is pretty forgiving when it comes to under or overfeeding and there's no need to mess around amending the pH of your feed, as the soil will buffer it for you.
Growing with pots and soil is a great introduction to indoor gardening; it's a cheap way to get started, soil is pretty forgiving when it comes to under or overfeeding and there's no need to mess around amending the pH of your feed, as the soil will buffer it for you.
Growing with pots and soil is a great introduction to indoor gardening; it’s a cheap way to get started, soil is pretty forgiving when it comes to under or overfeeding and there’s no need to mess around amending the pH of your feed, as the soil will buffer it for you.
It’s pretty straightforward for a new grower to get their head round the watering schedule for their plants, if the pots feel light it’s time for a water, if the pots feel heavy, just leave them for a couple of days – it’s not rocket science! Plants are also pretty good at telling us when they are hungry and need feeding or, on the flip side, if we are feeding them too often and killing them with kindness!
Knowing when and how to re-pot a plant can be confusing, but once you get your head around why you need to do it, then it all starts to make sense.
Why pot up?
If you are new to growing in soil and pots, you may well be asking yourself, why don’t I save myself the effort of potting up and just plant straight into my final pot? In theory, this is possible, particularly if you only wish to grow small plants or you are growing auto-flowering plants – which will begin flowering after a couple weeks growth.
Inoculate you media with a mycorrhizal at every stage of potting up
It’s worth mentioning at this stage that you should avoid re-potting plants that are flowering. When a plant is flowering, it should be directing all available energy into producing flowers, not roots or new leaf growth. Its root zone – its foundations – should already be established by the time you switch to flowering. The stress of re-potting will also have a detrimental effect on the yield of the plant.
Potting a small plant into a very large container will slow its growth for two reasons;
1. It will focus its energy into producing roots to fill the available space in the container, rather than focussing it upwards producing leaves and branches, so the plant will spend time growing down instead of up.
2. When you water a large pot with a small plant in it, the media will stay wet for a long time. This is because there are not enough roots in the container to uptake all the water and nutrient. The saturated media will contain less oxygen, which further slows growth.
The key to fast growth in the vegetative cycle is to start with a small container, encourage the plant to fill it with roots as quickly as possible and then pot up to the next size of container before the plant becomes pot bound.
‘Pot bound’ refers to when the roots of the plant have filled the pot completely, become incredibly tight and begin to grow into each other. The amount of available oxygen in the root zone will decrease and plant will basically stop growing. A slow-down in growth is one of the first indications that you need to pot up.
The second indication will be yellowing leaves. Most growers understand that yellowing leaves is a signifier of underfeeding and increase the dosage of nutrients when they next water, and in the majority of cases this is correct. However, when your plant is pot-bound there is simply not enough space left in the root zone for new growth and the root system is struggling to sustain the existing growth. This can be rectified by more frequent feeds, but it is easier to just pot up.
After yellowing leaves, the final – and most obvious – signifier is that leaves will start to die off. If your plants get to this stage there is clearly something wrong and the roots are choking out nutrients.
When to pot up?
When re-potting a plant, the size of container you choose will be dependent on how many times you want to re-pot throughout the growth cycle, how soon you want to flower your plants and how large you want your plants to grow.
For a regular growth cycle – around 12 weeks – you probably won’t want to pot up more than two or three times, that is;
- The first pot up; placing the starter cube into a small 10-15cm pot – some growers even plant seeds directly into these small pots and place a plastic bag over the top to act as a mini propagator.
- The second pot up; once the roots of the young plant has filled the starter pot they can go into the next size up – anything from a 3 litre to 11 litre pot – for many growers, this will be the final pot that they flower the plant in.
- The final pot up; if you’re growing bigger plants and want to finish them in a relatively large container, you’ll want to do a third pot up and let them fill this final container before switching them to flower.
Remember that to get the most from your pot; you want the roots to fill the pot before you switch the plants to flower. Otherwise, you are just wasting growing media.
Inoculate you media with a mycorrhizal at every stage of potting up
How soon you want to flower your plants is a major consideration when deciding on your final pot size and how many times you’ll need to pot up. Obviously, every grower is aiming for maximum yields, but you need to decide if you want to achieve that yield by growing lots of plants and switching them to flower quickly – which will keep them small – or, if you’re aiming for large yields from each individual plant.
If you want to do the latter, then you’ll need a longer vegetative period and larger pots. Think of the vegetative period as the time to build the foundations of your grow, because once you switch to 12 hours of light to flower the plants, they will stretch and then you’ll want to pretty much stop root and leaf growth and divert all their energy into producing flowers. The size of the flowers that they produce will be relative to the foundations built during the veg period.
What to pot up into?
Unlike your local garden centre, your local grow shop is unlikely to stock ceramic or metal containers. That is because these containers can leach substances when they become wet and this can upset the balance of nutrients in the growing media, they also tend to have pretty poor drainage – particularly ceramic containers – and this can leave your plants water-logged and slow their growth. For the best results, it’s safer to stick with plastic containers.
Plastic containers are fairly low cost and come in a variety of different colours – the cheapest usually being black. It can be tempting to head down to your local garden centre and pick up some really cheap terracotta circular pots, these will certainly do the job, but I’ve always found that they crack easily and can’t be used again. Personally, I prefer the more heavy duty black plastic pots that can be used for a good few grows – as long as you can be bothered to clean them! And, as a side note, it’s nice to support your local grow shop by getting your pots from them.
A healthy looking rootball, ready for potting up
When you visit your local grow shop, you’ll be faced with a wide range of containers of varying sizes and shapes. Whether you go for a square or circular pot is really down to personal preference (and what they have in stock at the time), square pots are more space efficient as they can be placed next to each other with no wasted space. If you are going for a large container – over 18 litres – then these are usually only available in circular sizes.
One fairly recent addition to the market are air pruning pots. These are designed to increase the root mass of the plant, resulting in faster vegetative growth and, ultimately, larger yielding plants. Air pruning pots have perforated sides which expose the tip of the root to the air when it reaches the side of the pot. In a regular pot the root would simply circle round the side of the pot, but in a pruning pot its progress is halted. This causes the root to put out secondary roots, which in turn reach the side of the pot, are air pruned and put out their own secondary roots. So, a larger root mass is created, which means greater nutrient uptake and faster growth.
Don’t let your plants get pot bound!
Air pruners are available in a few different variations, each with their own pros and cons; the air pots come flat packed and are easy to transport – and conceal - but need to be assembled before you use them. There are air pruning pots made out of soft fabric material, which are great because they’re easy to conceal in a bag when you’re walking out of the shop, but - being practical - they can really only be used once as the roots grow into the material and need to be scraped out once the plant has been harvested.
A good compromise are the root pruners that are shaped like a circular pot with slits cut away in the sides of them. These can be stacked like a regular circular pot and certainly work as well as the other air pruning pots out there. Again, it’s all down to personal preference and experimentation.
One thing to bear in mind with all air pruning pots; is that the media in the pot will tend to dry out faster than it would it a regular ‘solid sided’ pot because of the additional exposure to the air. Couple this with the fact that – if the air pruning pot is doing its job - there will be an abundance of roots in the pot (increasing uptake) and you will find yourself watering your plants more often.
How to pot up?
The first thing to do when re-potting a plant is to ensure there is adequate drainage in the container. Poor drainage will cause the media to become water-logged (saturated); this reduces the amount of available oxygen in the root zone, which will slow growth. So the water needs an escape. Most pots available from grow shops come with several drainage hole in the bottom.
It’s a good idea to put a small layer of clay pebbles into the bottom of the pot before you add your soil. This will provide an extra level of drainage and will prevent the soil at the bottom of the pot from sitting in the run-off after each watering and becoming saturated.
Root pruning pots provide a larger root mass than regular pots
Next, remove the existing pot from the plant by gently sliding it off, taking care not to damage the roots. If you have left the plant in the pot for a little too long or if you are re-potting a mother plant that has been in the pot long-term, you may need to loosen off some of the roots.
If the roots are not freed, they may continue to circle, instead of reaching out to the new soil and will slow down the growth of the plant.
Fresh soil should be placed in the new container on top of the layer of clay pebbles, keep filling and then use your hand or a scoop to make a hole for the plant. If you’re using an inoculant in the soil, like mycorrhizal granules, then sprinkle a good layer into the hole before adding the plant.
The plant goes in and soil is added around, until the container is full to the brim. You can then pat the soil down, to secure the plant in place. The top of the media will then be about half an inch lower than the top of the container.
Give the plant a light watering and let her settle into her new home. Re-potting will cause some stress so it’s a good idea to give a small dose of stress relief like a vitamin booster or nitrogen booster, applied as a foliar or watered in.
Job done!
S
Soft Secrets
