As Stef said in her third post, the rainbow rocks are the reward for completing the Rainbow of Fish.  You can only plant mushrooms in them, and they become RTH immediately :)

IMPORTANT!!!!!
In light of recent events there has been change made in the design of the Green house reward and I am sadden to say that the initial reward(message to you once you complete the challenge) was changed from :

Congratulations - you have successfully completed the 'Topiary Trail' challenges! Your reward is this useful little Greenhouse!
Your Greenhouse can store up to 3 items (plants or food) with time frozen until you wish to use them again.

To:
Congratulations - you have successfully completed the 'Topiary Trail' challenges! Your reward is this useful little Greenhouse!
Your Greenhouse can store up to 3 plants with time frozen until you wish to use them again.

Which means you can only store PLANTS like: supershroom,old Christmas trees, rare plants like Percy Pineapple or plants that take long time to get ready for harvest like the Ventus Quatriflorus.

Instead changing the visual tutorial and reposting all this again I am adding this note .

Step 4.(OPTIONAL) Once this is done remove the original plants (the roses if you had skunk or deter the regular wildlife) so you will eliminate competition for the food so you won't wonder why topiary skunks hasn't visited you.PLEASE NOTE that skunks eat from low plates.
TIP: The more topiaries greater visit frequency and less wrc ,dragons and mice. If you have lot of seeds you can do multiple topiaries at the same time, but don’t put too many i.e. two is enough unless you feel you can handle more because it is expensive to hunt for the hunting tasks and you will need a lot of diamond dusts for the plants and bushes.
 
Step 5.Once you completed the task that your first topiary gave you (for example you spotted ONE topiary skunk and attracted THREE topiary skunks for the red pot scenario) you move onto the SECOND STAGE OF THE SAME TRAIL where you get the grey squirrel challenge/bush/tasks in the same red pot (no new green seed is used!).The skunk gets replaced with new baby topiary plant which is automatically set for the next common wildlife once you fully dust it (in this case with the red pots: Grey Squirrel)
 
Step 6.Repeat the skunk scenario with the sq

Further more :
 
This challenge does not ends with you doing each trail once.In order to advance one level up and unlock the next pot you need to redo once all previous colors where :
 
violet    1 time    Quests : Attract 8 ,Spot  4
indigo   2 times   Quests : Attract 8 ,Spot  4
blue      3 times   Quests : Attract 7 ,Spot  3
green    4 times   Quests : Attract 6 ,Spot  3
yellow   5 times   Quests : Attract 5 ,Spot  2
orange  6 times   Quests : Attract 4 ,Spot  2
red       7 times    Quests : Attract 3 ,Spot  1
 
 
This is the message you get in pot shop when you unlock violet trail:
To finish this challenge (and hopefully get the reward):
• Complete the Violet Topiary Trail  [Details]
• Complete the 2 Indigo Topiary Trail  [Details] 
• Complete 3 Blue Topiary Trail  [Details]
• Complete 4 Green Topiary Trail  [Details]
• Complete 5 Yellow Topiary Trail  [Details]
• Complete 6 Orange Topiary Trails [Details]
• Complete 7 Red Topiary Trails [Details]
 
 
STEP BY STEP GUIDE FOR RED POT
(just to give you detailed walk through on how the whole process will go

IMPORTANT FACTS:
 
-Auto-planting new bush DOES NOT TAKE A SEED from your stash. So to complete one trail you will need one seed (unless you fail of course) and one pot regardless if the trail has 3 or 21 stages/animals.
 
-Once you have completed the task the bush AUTOMATICALLY RESETS -which means if you don't want to finish the task -for example you want to attract more animals from that bush you simply don't go and hunt the animals needed to spot for completing the task.
 
-Once you complete a stage the bush STAYS IN THE SAME POT and resets to baby bush -"growing happily". Then you repeat the dusting and talking to the bush to find out the new tasks. You can also check to see which stage you are when you hover on the bush (example : Topiary Trail Stage:2 of 6 ). For the first (red) trail you have total 3 stages,for the orange trail you have 6 -which naturally means you will have 3/6 different shaped bushes in the same pot and so on.
 
-IMPORTANT:If you find yourself in situation where you have to trim/hunt/attract the same animal on 2 or more bushes then move leftmost the one you want completed first. In case the animals attracted/spotted

When your bush is “fully grown” it has task (first) for you. To find out what it is hover on the bush like you want to water it . Under the watering can there is question mark. It says : Help!(Which wildlife will trim this Topiary?) Click it. You will see a picture of the animal you need to attract in order to trim the bush with short explanation : "Trimming Your Topiary :The wildlife you need to attract to your Garden to trim this particular Topiary Bush is the (animal) It only needs to be spotted in your Garden once (by anyone) and it will trim your Topiary for you!" So to proceed set up your garden for that particular animal. For example if it is skunk plant rosa amora. Once this animal visits and it gets spotted it will trim your bush and it will have shape. Therefore you are ready for your second (attracting the topiary animals) and third task (spotting the topiary animals).
Again the bush will have question mark that will say: "Hello! I'm the Topiary (animal :for the example the skunk)- thanks for growing me! To advance to the next stage of the  Red Topiary Trail, complete my quests below:Attract me 3 times in your Garden (0 attracted so far)Spot me once in other Gardens

PLEASE before starting this challenge take a time to read through this tutorial so you won’t make any (or fewest possible) errors.
 
Explanation of the concept:
There are 7 trails/levels/colors of topiaries consisted of different number of stages (from 3,6,9,12,15,18 and 21 for each color respectively) and different number of animals where every new level contains all animals from the previous trail plus new 3:
-Red: Skunk, Grey squirrel, Classic unicorn (total 3 stages)
-Orange: All animals from red trail plus: Meerkat, Tortoise, Winged unicorn (total 6 stages)
-Yellow: All animals from orange trail plus: Ostrich,Hedgehog, Black unicorn (total 9 stages)
-Green: All animals from yellow trail plus:Giraffe,Woodpecker,White unicorn (total 12 stages)
-Blue: All animals from green trail plus:Badger, Elephant,Baby unicorn (total 15 stages)
-Indigo: All animals from blue trail plus: Crane,Zebra,Golden unicorn (total 18 stages)
-Violet: All animals from indigo trail plus:Kangaroo,Leopard,Rainbow unicorn (total 21 stages)
 
NOTE: There is no order in which the animals will appear -they are random except the last stage which is alwa

I see all these new critters, well they didn't exist prior to 2013 when I last played. I had mastered the fairytales and underwater gardens before closing my old profile and games.
Now there are painted pots challengs, choc.bunnies, dinosaurs, cute alien looking critters 💆🏽‍♀️ so many different critters 🥰
Right now though I'm happily making my way through the level one Quests.
Good luck with your dino challenges 🙏🏽

nightingale notes

A = Monday      Red
C = Tuesday     Yellow
E = Wednesday  Blue
G = Thursday    Violet
B = Friday       Orange
D = Saturday    Green
F = Sunday       Indigo