A question that is regularly asked at this time of the season is: “when should I transplant my seedlings from the seed tray (or similar) into their own pots?”
Some growers do this at the earliest opportunity – when the seedlings are large enough to handle – at about a week or two after germination. I prefer to leave them a bit longer – until their first true leaves are about the same length as their seed leaves – three to four weeks after germination.
It’s good to allow the seed compost to dry out slightly so that you can prick out (or tip them out) with most or all of the roots intact.
Watering Seedlings and Establishing a Good Root System
When transplanting (potting on into a bigger pot), it is always good to encourage the roots to become established as soon as possible. This is done after the first watering – in a wet dry cycle.
After a thorough watering, it is best not to water again for several days – or until you have to! This makes the roots work hard and develop well – receiving more oxygen as the soil dries out and growing in search of more moisture and nutrients.
Don’t do this …
After the first thorough watering, keep topping up with small amounts of water .This will slow root growth and prevent oxygen from entering back in between the soil particles. If roots don’t need to search for water – they won’t and their size is reduced.
Obviously, keep your eye on them as the soil dries out – if they begin to wilt, the quickest way to hydrate them is with a spray/mist of water. Then water them thoroughly again.
Weight As An Indicator
It’s good to feel the weight of pots when watered, so that you can tell when most of the water has been used up – by regularly lifting the pot.
Don’t do this either!
Standing small pots in a tray of water 24/7 will also cause reduced growth and probably root disease.
When it comes to watering, it’s impossible to keep the compost, or other media, “just moist” for very long, but by using a wet/dry cycle, we can get the best of both worlds – moisture and oxygen in the root system.
Your little plants will grow more quickly and be healthier too!
Give seedlings a day or two to recover after transplanting before putting in full sun.
A One Plant Reservoir System
I have to say that this is my favourite home made reservoir system – it’s not a new idea but has been around for some time.
- An upturned pot sits in a large bucket.
- The tomato pot sits on the upturned pot.
- A capillary matting strip is used as a wick – similar to the Quadgrow Planter
This is an ideal method for all sorts of reasons … it’s cheap and one plant can fit in a small space anywhere around the garden or greenhouse.
The lower bucket holds plenty of water and nutrients.
You could use a bucket for the tomato plant – with holes in the bottom of course but you probably don’t need a pot that big.
In systems where water and nutrients are on supply 24/7, large containers of soil for root systems are not as crucial – the reservoir means that plants experience less stress when temperatures fluctuate widely because they always have access to water.
Issues of light and keeping the reservoir free from debris and leaves etc.
The soil surface
When watering from above, you may notice algae forming on the soil surface. This is very common in July and August as we water frequently and soil remains damp on the surface. The problem with algae is that it encourages disease and small gnats that feed off of our split tomatoes (just the odd split tomato that is!;).
A great way to avoid algae is by keeping the soil surface light proof with the use of clay pebbles.
Two or three centimetres of pebbles at the soil surface will keep the light off the soil and also encourage the surface roots into the pebbles for plenty of oxygen – a win-win situation!
Drainage – Instead of crocks
Clay pebbles can also be used at the bottom of pots.
This allows plenty of air for roots and the soil isn’t saturated at the bottom of pots for long periods. When pots are watered in trays, clay pebbles won’t cause the disease problems that saturated soil can. Thanks to John N. for the clay pebble tip!
It’s also Important to keep the reservoir light-proof
A skirt of plastic sheeting attatched to the tomato pot that overhangs the top of the reservoir bucket will stop debris from falling in the reservoir and reflect the sun from the pots on a hot day. This keeps the water algae-free and the little critters away!
Plastic sheeting – black one side, white the other – can be purchased from hydroponic stores (on Amazon too) at around £1.50 a meter. It is very handy for all sorts of jobs when light-proofing and reflecting etc.
Keep those seedlings in the light!