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 squirrel bush: Dust the bush, speak to it, attract the grey squirrel, get it trimmed, speak to it again, complete the squirrel challenge (spot ONE and attract THREE topiary squirrels) and get new and last bush for this TRAIL- THIRD AND LAST STAGE- UNICORN.
 
Step 7.Repeat the skunk/squirrel scenario with the unicorn bush: Dust the bush, speak to it (or not as you know it will be unicorn so go ahead and plant the pink cap mushroom in the rainbow rocks OR (if you don’t have the rocks) have the pink cap mushroom planted and fully dusted BEFORE you dust the unicorn bush OR use fully grown enchanted pink mushrooms), attract the regular unicorn, get the bush trimmed,(harvest the RFH mushroom and put fully grown enchanted mushrooms or supershroom) speak to the bush again (or don't as you know already that you need 3 spotted and 1 to spot), complete the unicorn challenge (spot ONE and attract THREE topiary unicorns).This time the bush stays same except that the unicorn’s leafs will turn brown and you can harvest it manually and move onto the orange pot or redo the red pot again as you need total 7 for the whole challenge.
 
Step 8.
When you complete the whole red trail you can buy the orange pot and start/repeat the same process except with more stages (6) and more animals needed to be attracted (4) and spotted (2). In the pot shop you can find info about requirements for next trail.

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):
 
Step 1.Buy red pot and plant green seed in it(found in misc section in seed shop) then dust the topiary till it is fully grown.
 
Step 2.Hover over the bush and click "? Help! (Which wildlife will trim this Topiary?)" It looks like this:"Trimming Your Topiary! The wildlife you need to attract to your Garden to trim this particular Topiary Bush is the Skunk.It only needs to be spotted in your Garden once (by anyone) and it will trim your Topiary for you!"
 
Step 3.Set up the garden for skunk and attract only one of them.When spotted it will TRIM the bush into the shape of skunk.Hover over the skunk bush and click "?" Speak To The Topiary Skunk (It will have a task for you!) " It looks like this:"Hello! I'm the Topiary 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 (0 spotted so far)Make sure you complete these tasks before I become Ready For Harvest (in 4 days, 23 hours.) As soon as you have completed them, I'll plant the next Topiary Bush for you in this same Pot!"
Also there are pictures of the animals needed to be attracted and spotted
It will tell you what you need spotted in YOUR GARDEN and spot IN OTHER GARDENS to complete the first stage of the red topiary trail (just like the nests tells you which bird you need to hunt for).
 

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 don’t go on the left bush contact the developers-it is a glitch!
 
-You can see how many trails you did in:
1.The pot shop in the section Topiary ;
2. Fruits Harvested / Rainforest Adopted  [info] at the bottom of your garden
 
-Plant ahead and don't remove RFH(ready for harvest) plants unless you want to wait them again to go RFH
 
-IMPORTANT: Trail is completed /counted as completed once you harvest a bush after you finished ALL STAGES and tasks for the stages (i.e. you are at 9 out of 9 stages on the yellow pot- which is Topiary black unicorn and attracted 5 and spotted 3)The color of the pot that bush is in =is the color of the trail completed.Once you finish a STAGE you will get notification.
 
-Having rainbow rocks is really useful .They come as reward for completing "The Rainbow Of Fish challenge " Their purpose is to plant any mushroom in it and get it instantly RFH so you can get specific unicorn easier
 
-You can play the game without rainbow rocks -using the fully grown mushroom that is one level higher from the unicorn you need.(Example: use fully grown white mushroom if you need black unicorn)
 
-You CAN'T PLAY the levels that require higher level mushroom that you haven't unlocked yet,but that doesn't mean you can't play at all.If your last unlocked mushroom is Enchanted black mushroom you can easily finish the third trail - the yellow pot.
 
-Each stage of the trail opened for quests lasts exactly 5 days (once it reaches fully grown the timers sets off) The other 5 days are on newly planted undusted bush that is "Growing happily" -which sums it up to total 10 days
 
-You don't need more than one of each color of pot for the whole challenge
 
-You need total 28 seeds (unless you mess up somewhere)
 
-You need minimum 340 pink gems
 
-It helps a lot to pull the plants that attract the critter needed to shape the bush (especially in higher level trails) in order to reduce the competition but it is not mistake to leave them especially with the tortoise as you will need that plant again and it takes day and a half to go RFH.It is just as the advantage of having supershroom over fully grown enchanted mushroom so you won't have to battle with dragons ,mice and myth birds for the squirrel
 
-You can/should plant in advance (especially from the green pot and above) if you have space or if you are short on gems as no plant attracts anything if it is growing happily"
 
-NOTHING THAT YOU SPOT/ATTRACT COUNTS BEFORE AND AFTER having the bush trimmed in shape. This means that you have FIVE days to trim/attract/spot ALL animals for the given stage. NOTE : this is not applied to the whole trail but ONLY FOR SEPARATE STAGES. Thus ,prepare the garden see what you need then go hunt.Anything else that you spot counts towards the magical number 10 that gives you topiary seed for every 10th,20th,30th same topiary wildlife 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 (0 spotted so far)Make sure you complete these tasks before I become Ready For Harvest (in 4 days, 23 hours.) As soon as you have completed them, I'll plant the next Topiary Bush for you in this same Pot!"
This means that you have FIVE days to trim/attract/spot ALL animals for the given stage. NOTE : this is not applied to the whole (red in this case) trail but ONLY FOR SEPARATE STAGES.The tasks are really nicely done with pictures and counters so you can't miss what you have to do,what you did and what are you missing to complete the task.
Don’t worry if this seems too confusing I have written step by step tutorial at the end of this elaboration so you can follow it if you are lost.
 
When you attracted and spotted the animals the bush has asked from you (i.e. you colored the pictures that you get when you click the question mark on the topiary)  that stage will be done and you will get notification PLUS a new bush will be automatically planted in the same pot with new animal and new tasks!
 

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 always the (new) unicorn for that level (For example stage 12 on the green trail is White unicorn .All other animals come in random order including the other unicorns). However if you finish (or even fail a trail) the animals you had on that particular level of a trail will be exactly the same if you use the same pot. But NOT if you use different pot. So make notes for every appearance and KEEP THE POTS.
 
The reward for completing the topiary challenge is GREEN HOUSE!
Its located in new shop section and unfortunately you can't put it in the garden.It is not an item it is additional shelf with special properties.The message you receive upon completing is the following :
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.
 
 
If you want you can check this visual tutorial : http://postimg.org/image/6ocparm7d/
Feel free to save the link or download the file .
 
Also you can “predict” what animal is coming if you look carefully at the bushes and compare them with your notes excluding the animals you already had. There are two types of bushes: Tall and Round bushes.
Animals that come from tall bush are: ALL UNICORNS, meerkat, ostrich, giraffe, badger, zebra, crane, kangaroo
Animals that come from round bush are: grey squirrel, skunk, tortoise, hedgehog, woodpecker, elephant and leopard
 
Each stage holds for you 3 tasks and gives you total time of  total 10 days to complete. BUT: Once you plant a bush it is ”growing happily” and you can only see if it is round or tall. In order to proceed you need to either dust it to fully grown or leave it to grow by itself which will take 5 full days.Once it reaches “fully grown” you get new 5 days till it goes ready for harvest and YOU CAN NOT DUST OR REMOVE IT (if by any chance you want it removed you will have to contact the developers.To do that for you through” Contact us” link at the bottom of every page in Fairyland)
 

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