Photosynthesis: A world where you can grow your own photographic supplies

Rosie Horn lets her images develop slowly on the actual plant which is how she works with the chlorophyll photographic process.

Writer and photography / Rosemary Horn

Photosynthesis photographic processOverview of the chlorophyll process

Make a positive (not a negative)

  • Even out tonal range
  • Print on transparency

Pick a leaf

  • Vegetable leaves such as Spinach and Pak Choy
  • Leaves from undergrowth plants such as Lily, Nasturtium
  • Leaves from trees with soft broad leaves

Sandwich together in a contact printing frame

  • Make sure the leaf has maximum contact with the positive

Put in the Sun

  • Length of time could be half a day to 1 week

Materials for printing photographs with photsynthesis

  • Inkjet printer
  • Inkjet transparency
  • Sellotape
  • Scissors
  • Leaves
  • Contact printing frame

Image above right: An example of an image that didn’t get quite enough sun. Good detail but lacking in contrast that would have come from more time in the sun. A bit unevenly exposed from trying to cram to many printing frames into a space to small.

Making prints on leaves is a hit and miss affair. There are a few factors outside of your control that will affect the final outcome, such as the amount of sunshine, the type of leaf and its reaction to the available sun.

The key area to focus on is creating a good positive, this will make the world of difference to your success rate.

Negative for photosynthesis prints
I experimented with using negatives. I rephotographed a photo using a 4×5 Copy camera to make it a Positive. The positive had good detail but still too dense so not as much detail was recorded by the leaf. Printing my own positives on inkjet was faster, for those dedicated to film it is a good option.
A nature print on spinach
Photosynthesis print on spinach.
chlorophyll print on a leaf
Thick Broadleaf: This is quite a thick leaf, quite dense too, I didn’t think it would work but it was quite successful. Best to try lots of leaves as you just never know what might work.

After taking photos (I use digital) you then need to process them in Photoshop to convert them to black and white. You need to aim at creating a positive that is even enough in tonal range to achieve maximum detail yet still with enough contrast to make it dynamic. The tonal range of a leaf is narrower than photographic paper. Using Levels helps to even out the tonal range. Avoiding photos with large areas of strong darks and highlights will help improve your results. By masking a dark or light area you can use the levels to even the tone and create more contrast.

I print the finished positive using an inkjet printer onto transparency. I print two copies to achieve enough density, I sellotape them together and then sellotape another layer of transparency over the exposed ink of the print so that it doesn’t stick to the leaf or the glass becoming ruined, the positives should be kept and looked after, they are not throw away items. You may prefer to use traditional negatives which also work well if you get the exposure right, not too dark as they tend to be to dense and the leaf will struggle to pick up any detail.

I would suggest experimenting with making your positive as what has worked for me in New Zealand may not be appropriate for conditions in Europe or North America or wherever you may be.

Photosynthesis on pak choy.
Photosynthesis on pak choy. Using green leafy vegetables is a good choice. You can buy them or grow them for yourself, use them for photos or eat them.

I then pick a leaf I want use and put the positive on top of it and sandwich it in my contact printing frame. I make sure the leaf is as flat as possible, making sure the frame is very firmly sandwiched together. If the leaf has a particularly solid stem you can build up the surface behind the leaf with card until you can achieve good contact with the positive.

I put this in the sun and depending on the sunlight I check it during the day or in a couple of days. Contact printing frames have a hinge at the back so you can undo half the frame and pull the leaf away from the positive to see how much it has developed. Each leaf will react differently every time, but you will start to get a feel for when the leaf has reached its optimum.

Once the image is on the leaf, the leaf will be very thin and very delicate, as they dry out completely they can become quite brittle so it is important have a book or folder to store them in, something with quite firm pages. To mount them I used some acid free glue and used a small amount to fix them to some Acid free card / matt board.

These images are unfixed, so if you choose to display them bear this in mind. You can always make more.

Rosemary Horn works in anthotypes and photosynthesis.

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14 thoughts on “Photosynthesis: A world where you can grow your own photographic supplies”

  1. I wonder if the prints could be preserved by sandwiching them between two sheets of wax paper and sealing with a hot iron? We used to do that with autumn leaves. The iron makes the wax (semi) clear.

  2. I would really like to hear a little bit more about how long this process actually takes to work. I’m a high school senior studying Alternative Process, and am in the middle of this project right now with paper positives, lettuce, and kale.

  3. Hi Ellie, Sorry for not replying sooner I didn’t click the right things to get notifications of posts. You can use film negative, you do need a positive image to make a positive print on a leaf. When I had a go I printed a negative image (so the print was in the negative) and then rephotographed it onto 4x5inch film using a copy camera to get a positive image on negative film. It is quite a lot work to make an image this way, why do you want to use film? Otherwise the process is they same sandwich your film and the leaf in a contact printing frame and wait.
    Good luck

  4. Hi Andy, thanks for letting me know about these other approaches. I am familiar with the resin idea but it is to toxic so I won’t use it as it doesn’t fit with the ethos of my work.

  5. At Photographs in New Orleans, I saw a series of work done where they potted the leaf in fiberglass resin after they were done exposing if. They were saying they pressed the leaf while it was still attached to the plant so the chlorophyll naturally left.
    Karen bought one a few years ago & the image seems fine today.
    I’ve also seen exhibits where people took close shaved sod and either exposed them to sun under a big negative or just projected the image on them so the chlorophyll died offing he shadow areas. These were still living sod so the image was transient after the sod was exposed to light w/o the image overlay.
    I’m really sorry. It I don’t remember the names of the artists involved..

  6. Hi,
    i was thinking about doing this process for my a2 photography coursework.
    Do you know how to do the process with regular negatives from a film camera? If so can you go into a bit more detail in how to do it please? It would be greatly appreciated 😀
    Thanks x

  7. Awesome work!

    I’ve seen this done where a negative was used and light was shone on the leaf for about a day or two (pretty much what you did here). However, then they took the leaf and stripped off the chlorophyll with some boiling alcohol. They then took a tincture of iodine solution (you can still buy this at some pharmacies or I can show how to easily make it), left it on for a few minutes, then rinsed with cold water. The idea here is that the places that were exposed to light produced starch (product of photosynthesis), whereas the sheltered sections did not. Starch forms a decently stable complex with iodine, giving a dark color. This effect can probably be enhanced by keeping the plant in the dark for a day before the exposure, that way any amount of starch produced in the day of exposure will be maximized and of significant difference from the rest of the leaf.

    Not sure exactly how long this starch-iodine complex lasts, but I would imagine quite a while, as long as it is kept in relatively inert conditions.

  8. Hi Christopher,

    I tried a UV light used for cyanotypes but it didn’t work after 10 mins. The idea for me was to use a natural process for a low impact environmental print so I was not interested in pursuing an artifical light where there is so much natural light around. I don’t think an artificial light is strong enough to create an image before the leaf dries out, but I could be wrong.


  9. Have you tried using an enlarger or a high watt light bulb instead of sun light to streamline the process? If so, is there a time you suggest for different types of leaves?

  10. To answer Kathleen and Kory,
    I haven’t tried fixing them yet, I am trying to work out what would work. Perhaps using a mordant that is used to fix natural dye to natural fibre.
    In their un fixed state they will last a long time – years – if stored in an album. Much like the Victorians whokept pressed plants and flowers which are still around today. If exposed to sunlight then maybe a week or month depending on the strength of the sun.

  11. Hello Andrew,

    Not I haven’t tried this, but it would certainly be worth a try.
    I have been asked about using a camera obscura before, the light is far more restricted using this or a view camera. Using the contact printing method the exposure is a few days so I imagine it will take even longer using a view camera and the leaf has a limited time frame for it to work. The other issue with the time it takes is movement and the sun moving. Like I said definitely worth a go to see what happens. Thanks for your suggestion. Let me know if you try it yourself.

  12. Thanks for the article, Rosie. Question: Have you ever tried sandwiching a leaf between two glass plates and putting it in a view camera, leaving the shutter open on a scene all day to see if you get a positive?

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