Grow lights

Advice on how to grow Lithops in your area.
GraemeAustralia
Posts: 4
Joined: Sun Dec 31, 2017 4:39 pm

Grow lights

Postby GraemeAustralia » Thu Jan 11, 2018 2:05 pm

Does anyone know of a decent study showing what the optimum light level is for adult and seedling lithops?
I have searched and can only find generalisations- nothing that mentions the maximum Lux levels to achieve saturation. Perhaps the studies have not been done but that seems unlikely.
Any help would be appreciated.

Graeme

Australian
Posts: 331
Joined: Thu Jul 16, 2015 12:08 am
Location: Australia

Re: Grow lights

Postby Australian » Thu Jan 11, 2018 7:46 pm

I don't know of any, but Brom will probably know better.

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brom
Posts: 175
Joined: Thu Dec 15, 2016 8:24 pm
Location: Germany

Re: Grow lights

Postby brom » Fri Jan 12, 2018 6:57 pm

The studies are going on and on. It is now known that different plant species need different wavelengths for optimal growth. So it was recently found that the wavelength of 730 nanometers promotes the growth of certain plants such as roses or peppers. That's why not only light intensity is important, but also spectrum.
You are in Australia, I assume that you have enough sunlight. So you should not look for the maximum, but minimum light intensity at which the plants are well colored and look good. To achieve good color saturation, the natural light is best suited because it has complete spectrum and does not cost anything.
Photosynthesis rate can not be increased indefinitely by irradiation of higher light intensities. A chlorophyll molecule absorbs about 45 photons per second. Once this light saturation is reached, you could add dozens of growth lamps, but the result would be the same except for a high energy bill.
The small seedlings do not need sunlight, it is even deadly for the little ones. Reducing light intensity should not be a problem, I have another problem: too little light. That's why I'm forced to help with artificial light to get good-looking plants.
The light intensity requirements are therefore different for adult Lithops and seedlings. In addition, there are Lithops species that are colored worse with much sunshine. These are mainly green acf, which then turn yellow. In addition, there are species that grow in nature in the grass and the others in the open areas. So it's best to find out for yourself which amount of light is best for which species.
Viele Grüße aus Marienthal
Boris

GraemeAustralia
Posts: 4
Joined: Sun Dec 31, 2017 4:39 pm

Re: Grow lights

Postby GraemeAustralia » Tue Jan 16, 2018 1:50 pm

Thanks brom - You are correct and in Australia we have plenty of natural sunlight. And for adult plants managing their exposure is not a great problem. The difficulty for me is that the sun is so severe that getting enough light for my seedlings without cooking them is difficult. Although I realise there are other options if you have a suitable aspect in my case the best answer is to grow in indirect light and to supplement with diode lights in such a way that I can guarantee that the seedlings will not get damaged. I have ordered a PAR light meter and some red/blue diode panels and and have been trying to find literature that mentions what a sensible maximum for the seedlings would be. I have read in a paper on light penetration that the trial plants were kept in a growth cabinet with a light level of 400um m2 s but that is the only quantitive data that I have been able to find. I guess I will just have to do some trials and see what I can work out as the best compromise. I believe you are correct and that you can easily provide more light than necessary and that this can probably be done without hurting the seedlings as long as the internal temperature of the plant tissue is not raise above a critical point of mid to high twenties.

Australian
Posts: 331
Joined: Thu Jul 16, 2015 12:08 am
Location: Australia

Re: Grow lights

Postby Australian » Tue Jan 16, 2018 7:28 pm

The advantage is that with artificial lights you can maximize the growth of Lithops in the first 2-3 months to insure they get to a diameter of 0.5 to 1 cm. Also you can avoid the attack from pests since you can keep the growing area inside the house. You can produce light for 14 hours a day constantly. However, you need to keep in mind that you also need to ventilate the seedling with a little fan, if you use a growing tent.

I was at Bunnings today and saw Mr Fothergill's HydroGarden All-In-One Grow Kit. It's very simple and costs AU$70. It's used for herbs to be grown hydroponically. However, you can regulate the water to make it suitable to Lithops. With a cheap fan you can regulate the airflow around the kit.


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