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I read that for greens like salad you can provide supplementary light hours (during night time) in order to increase the growing speed. Some species even tolerate continuous lighting.

Is the same possible for strawberries? I'm not sure as the daily light cycle is supposed to trigger flowering and fruiting...

Vincent Teyssier
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  • Are you talking about salad greens being grown outside and then someone adds artificial lighting and is saying this increases growth speed? So then you are wondering if your strawberries outside would grow faster with artificial lighting? Is this to increase the light or extend the light during nights? I'd say add fans to blow the O2 off and around the leaves so that more CO2 can be produced. Way more production. Adding a source of CO2 is also another great way to increase production. Plants need rest my opinion. Periods of darkness. What are you doing for fertilization? – stormy Aug 14 '16 at 20:26
  • I'll edit my questions as I mean greenhouses where we extend the lighting period during nights. CO2 injection and nutrients misting to the roots are also expected but my question is here is about light and how the day/night ratio can be optimized – Vincent Teyssier Aug 14 '16 at 20:29
  • As long as you have optimal lighting, to add more is not going to enhance growth. To add more hours of light has been found to NOT help in fact deters the health of plants. Nutrient misting of roots? Why? When you want plants to go into budding one actually cuts the light/dark cycle down to 12/12. This signals to the plant the season is getting later in the year and to start producing seed. Now if you are in a greenhouse during the end of the season, you can slow the budding process by adding light to the beginning and end of the day. Depends on the plants and your goals. – stormy Aug 14 '16 at 20:39
  • I have to disagree with the first part as there are many well documented studies showing that increasing the DLI increases the biomass production at least during vegetative state. For everbearing strawberries an increase of DLI from 16 to 29 multiply the growth by 1.5. Regarding nutrient misting this is for a better and faster absorption of nutrients and o2. Thanks for the info about budding, so basically you reduce the DLI to send a signal to the plant that's time to flower :), right? – Vincent Teyssier Aug 14 '16 at 20:48
  • Yes, reducing the light/dark hours is a powerful signal to plants you want to go into reproduction growth. I am going to have to go out and take another look at this 'more light is better' even for vegetative growth. I do know there is a controversy with this. Do you have a good site to read? How do you 'mist' roots? These plants are in soil, yes? I kinda rely on micro/macro organisms for best uptake of chemicals. Do you check pH of the soils? pH is huge for uptake of chemicals by roots. – stormy Aug 14 '16 at 20:55
  • Misting is done aeroponically. The sprayer must have an exit below 0,025mm in order to atomize the water/nutrient in fine enough particles that it gets absorbed by the root immediately and does not drip. Basically you spray 5s every 3 mins and verify the coloration of the roots to adjust the misting cycles. I monitor ph too and always keep it between 5.5-7, ideally 6. As it is grown soil less there is no micro organism. Even the water is cleaned by reverse osmosis and UV sterilization. Then regular nutrients are added plus minerals from clay and other non organic materials. – Vincent Teyssier Aug 14 '16 at 21:02
  • For the lighting, a quick Google will give you plenty of results, specially for greens. You can google for Philips horticultural lighting or aerofarm if you want to see some typical set up. But I,m mainly relying on papers published on research sites and the figures are indisputable ;) – Vincent Teyssier Aug 14 '16 at 21:05
  • You are in a different realm that I have always avoided. Someone else will be along soon to share their experience. I know one book that you might love; 'The Cannabis Encyclopedia' by Jorge Cervantes. This is incredibly detailed and addresses concerns of those in commercial production. All about ONE plant but the chemistry, the huge spectrum of ways to grow were amazing. This guy did an amazing job. Good luck, I will definitely check this lighting stuff as I recently had learned more hours of light is not better. Shane Smith would be good to read. – stormy Aug 14 '16 at 21:12
  • Haha ok thanks for the reading advice. Actually I have already been told that I should look on Cannabis forums, but strawberries look a bit more particular and there are very few papers about lighting cycle so I was thinking of asking here with people hopefully having experience from the "field" ;) anyway thanks for the help :) – Vincent Teyssier Aug 14 '16 at 21:16
  • Strawberries more particular than Cannabis? Hey how old are your plants? The production is supposed to be reduced by the third year. I've got 3 year old plants and berries are greatly reduced (everbearing) this year. Last year was phenomenal with production. And I live in zone 1b, my greenhouse collapsed last October from snow. Strawberries still made it, healthy but low production. Make sure your N is below P and K... – stormy Aug 14 '16 at 21:22
  • I plan to renew 1/3 of my strawberries every years specially for that ;) Well I don't know a lot about cannabis so I'll look at it. What is your usual NPK ratio? – Vincent Teyssier Aug 14 '16 at 21:26
  • For any plants I need to harvest reproductive growth from, I use a light fertilizer; 4-7-5 or similar numbers as long as N is lower in percentage than P and K. I tried some fertilizer my hubby brought home that said great for tomatoes and vegetables. It was a percentage higher in N than the P and K and I'll never do that again! Lots of leaf almost zip with flowers. Makes a huge difference! – stormy Aug 14 '16 at 21:31
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    Ok good to know. I've continued my readings and the general advice is to use a 19-19-19 @3g per liter before flowering and then somlething lighter in Nitrogen once flowering starts. Nitrogen mainly helps developping leaves, which are the key element to high photosynthesis, so once the base is strong enough, as you said you don't want leaves to developp anymore but fruits, which would explain why you reduce Nitrogen when flowering stage starts. – Vincent Teyssier Aug 15 '16 at 09:32

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The interaction between photoperiods and temperature is not well characterised in USA strawberry cultivars. In Japan in unheated glasshouses they have experimentally prevented plants from entering dormancy with supplementary lighting in winter to extend their vegetative phase.

http://cals.arizona.edu/strawberry/Hydroponic_Strawberry_Information_Website/Supplemental_Lighting.html

Graham Chiu
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