1. step: making Orange Chameleana Flower (CF)
- plant 2 Red CF
- attract 10 Red Chameleons (RC)
- spot 10 RC
(you can first spot 9 RC, but it's very important first to attract 10 RC and then to spot 10th RC; if you spot 10th RC before attracting 10 red ones your red flower won't turn orange and after attracting 10th RC you will have to spot another 10 RC)

One red flower will turn orange.

2. step: Making Yellow RC
- plant another Red CF
- spot 10 RC - your red flower will turn orange and you will have 2 orange flowers
- attract 10 Orange Chameleons (OC)
- spot 10 OC

One orange flower will turn yellow.

3. step: Making Green RC
- plant another Red CF
- spot 10 RC - your red flower will turn orange and you will have 2 orange flowers
- spot 10 OC - your orange flower will turn yellow and you will have 2 yellow flowers
- attract 10 Yellow Chameleons (YC)
- spot 10 YC

One yellow flower will turn green.

4. step: Making Blue CF
- plant another Red CF
- spot 10 RC - your red flower will turn orange and you will have 2 orange flowers
- spot 10 OC - your orange flower will turn yellow and you will have 2 yellow flowers
- spot 10 YC - your yellow flower will turn green and you will have 2 green flowers
- attract 10 Green Chameleons (GC)
- spot 10 GC

One green flower will turn blue.

5. step: Making Indigo CF
- plant another Red CF
- spot 10 RC - your red flower will turn orange and you will have 2 orange flowers
- spot 10 OC - your orange flower will turn yellow and you will have 2 yellow flowers
- spot 10 YC - your yellow flower will turn green and you will have 2 green flowers
- spot 10 GC - your green flower will turn blue and you will have 2 blue flowers
- attract 10 Blue Chameleons (BC)
- spot 10 BC

One blue flower will turn indigo.

6. step: Making Violet CF
- plant another Red CF
- spot 10 RC - your red flower will turn orange and you will have 2 orange flowers
- spot 10 OC - your orange flower will turn yellow and you will have 2 yellow flowers
- spot 10 YC - your yellow flower will turn green and you will have 2 green flowers
- spot 10 GC - your green flower will turn blue and you will have 2 blue flowers
- spot 10 BC - your blue flower will turn indigo and you will have 2 indigo flowers
- attract 10 Indigo Chameleons (IC)
- spot 10 IC

One indigo flower will turn violet.

Now I'm not sure, but I guess we have to attract 10 Violet Chameleons (VC) and to spot 10 VC and violet flower will become Rainbow Chameleana Flower.

Some tips:
- You have to keep one flower of each color at all times.
- Each flower starts as red, change to orange, then change to yellow etc.
- You need to make at least 2 same flowers (of same color) if you want to change one of them to the next color.
- You can make 3 or 4 same flowers, for example 4 orange flowers and to change 3 of them to yellow.
- If you made for example 2 orange flowers  - you need to  hunt Orange Chameleons to change the color of one. If you have more green
   flowers - you need to hunt Green Chameleons, etc.
- You can hunt Chameleons of all colors but do not spot the 10th, 20th, 30th one, etc except if you want to change the color.
- If you made a mistake and flower of one color is missed now in your garden - just plant another red flower and change it until you get
   the color you need.
- Your flower doesn't have to be fullly grown to change the color. If you planted for example red flower and it's not fully grown, it will
   change  the color if you spot 10th RC (if you already attracted 10 red chameleons).
- If your garden is frozen flowers don't change the color.

Just to add / about different strategies:

You don't have to keep one flower of each colour at all times or have at least two of the same colour before changing one.
That's only necessary if you want to keep attracting the latest colour (or any at all).

As there is actually no point in attracting more than 10 of the latest colour, after reaching that (but also possibly in between) I would change colours whenever I can, especially on the lower colours, and don't bother about a "broken" setup. One can always plant more reds and bring them back in line later to move on.

One has 3 months per plant, so plenty of time to prepare for a next level in any way one likes.

Thanks, ladies!  I have been out of town and just started the chameleons this morning.  Has anyone figured out how many of each color we will eventually need to spot?  It's astronomical!

70 red
60 orange
50 yellow
40 green
30 blue
20 indigo
10 violet

total of 280

unless you want them all to get to rainbow in which case you'd need to spot 70 of each (assuming 7 plants)
that would be a total of 490

Benni is right - you don't have to get that 7th red, 6th orange etc to change colour
  so that's a total of 220 to get to rainbow, but still 490 to get all 7 there.

I have accidentally spotted my tenth indigo before I have attracted 10 ... do I have  to get 10 more or will it turn when I have attracted my tenth ?

You have to attract the ten first, same as with all the other colours, then your next multiple of ten spotted in other gardens will change the colour.

So I'm afraid you'll have to reach 20 spotted in other gardens, Penny.