Low Gear vegetative growing - a tactical slow down

Most of the time we strive to grow our plants as fast as genetics will allow. Faster growth from the start means more growth sites and fuller plants with less chance for pathogens and bugs to creep in, leading to the biggest yield in the fastest time.

Most of the time we strive to grow our plants as fast as genetics will allow. Faster growth from the start means more growth sites and fuller plants with less chance for pathogens and bugs to creep in, leading to the biggest yield in the fastest time.

Occasionally life throws a curveball that affects your grow schedule – moving house, illness, accident, holiday, leaky flower room that needs fixing, equipment failure… there are lots of reasons why you may need your plants to temporarily slow down to accommodate your needs for a change. 

A friend of mine grows on a very small scale. He has limited space so grows his seedlings in a small cupboard before transplanting into his main garden. Just as his plants were ready to be transplanted and triggered to flowering he had a car accident, which meant he would be unable to tend his much larger flowering plants for a few weeks – limited mobility meant he couldn’t clean and set up the hydroponic system and didn’t have anyone he was able to ask for help. The seedlings were now pretty large, and ready to outgrow their vegetative area in a major way. What should he do? How could he put the vegetative plants in low gear while he recovered?

Firstly it’s important to get your plants healthy. Methodically go through each one removing any dead or sickly looking leaves.  Check the roots, if there is any Pythium (“Root Rot”) remove these brown bits too. Hopefully you won’t need to do either of these treatments, but if you must then give them a little dose of a gentle vitamin stress buster afterwards to help them recover  e.g. “Super Thrive”, “Revive” etc.  If you have the facilities available then a good spray of Ozonated water can really help disinfect the leaves and roots of your babies too (See Ozone Article in previous issue).

You now have to go against a few of your most rigid rules, so prepare to change tactics – we don’t actually want fast growth for a change! Not until we are ready for it to speed up again anyway.

Firstly cut the Nutrient EC of your feed. Of course each plant is different, but just for example let’s say you are currently feeding Veg Nutrients to an established plant at 1.6 EC, PH 5.5.  I would suggest dropping the EC down to about 1.2 or 1.3.  This will slow the fast pace of growth, but if you slow the plant’s metabolism down in other ways too then you won’t get a deficiency. Stop feeding any high Nitrogen boosters or growth hormones too. Stick to just the basics of your full-spectrum balanced feed with no growth additives – the additives work best when everything else is optimised, so for our current situation of slow growth, additives would be equivalent to putting a turbo on a car with bald tyres.

The second big adjustment is to lower the temperature. Most popular hydroponic plants grow fastest in temperatures of around 70-80 F in the day, dropping by preferably no more than 10 F lower at night. Because we are looking to slow the metabolism and limit fast growth, we can drop the temperature down to about 60 F during the day, and a little cooler at night. This will slow growth considerably, but don’t worry it won’t actually hurt your plants. They can take it!

The third biggie is light! Of course it is important to stick to your current light/dark timing schedule (usually 18 hours of light, 6 of dark for vegetative growth), but do reduce the available light intensity as this will also help slow growth.  If you reduced the light without also lowering the temperature and feed EC at the same time then your plants would stretch considerably. This is why it is important to do all these steps concurrently.  It is still important to spread the light out evenly over your plants, as you don’t want any in shade, but you are looking to reduce the overall lumens reaching them by around half. Depending on what setup you have, you may be able to switch off some lights, or alternatively you could always raise the lights up higher above the canopy, thus achieving the same reduction in available lumens. Don’t raise the lights too far though as light intensity and distance follows an inverse square law – so when the distance from light to plant is doubled, the plants receive only a quarter of the available light intensity.

These three steps will slow plant growth considerably and will allow you to put the veg on hold for a few weeks without any long lasting damage to your plants. 

Another good idea to halt growth is to pinch out the growing tips. The plant will take a couple of days to catch up and force growth out laterally. You probably do this already in combination with other techniques to encourage full, bushy plants, but it can also be used to put vertical growth on hold for a little while. 

Make sure you keep an eye on your plants during this time. Don’t neglect the roots and watch out for pests. Longer in veg means longer for problems to develop, so keep up basic grow room hygiene and maintenance as much as possible. 

My friend who had the car crash put his veg plants on hold for over 7 weeks using these techniques! There were no complications, deficiencies or stretching and his plants are healthy growing at their usual fast rate again now.  

Once you are ready to get the plants back into full speed growth regime, it is as simple as going back to your usual routine – bring the light intensity up, raise the heat and raise the nutrient EC back to normal over the course of a few days, then start introducing your chosen boosters again. Your plants will adapt and you will be back on to your usual schedule!