Due to the fact that many people are stuck with this topiary challenge as there aren't many tortoise/meerkat gardens I would like to write my notes here so hopefully people can be encouraged to set up for these and move forward.Usually I put my notes on my back wall but I don't really see many gardens doing these so I hope they will be seen if I put them here.

To start ,other than the proper resources:gold pink gems,green seeds.. you need to buy pots from the shop (red pot costs 10 pink gems,orange 20..and so on) ,have rainbow rocks (it is not essential but it is easier) ,supershroom mushroom seeds,lots of diamond dusts and bag full of patience :)))

FACTS:

-There are 7 levels/trails of topiary where each trail is made of 2 common/average wildlife and one very rare i.e UNICORN.Have in mind I am talking about the OLD wildlife version. Topiaries are all AVERAGE.
Here I am talking about the overall view on the animals in the topiary section.

-Each trail (red,orange,yellow,green,blue,indigo and violet) is made of stages.3/6/9...NOTE: TRAIL is NOT same as STAGE.

-When you plant a bush it has status "growing happily" and you can dust it to fully grown.If you don't you have 5 days to prepare (for example if you don't have the rainbow rocks you can plant the pink cap mushroom although it can be done with the fully grown enchanted pink mushrooms too)

-Once fully grown you are supposed to "talk to the bush" to find out WHICH animal you have to attract to trim it and later on which animals you need spotted and attracted once it is shaped (yes you have to speak to it twice ,no you are not crazy :P).Just like the nests.Hover over the bush like you are going to water and click the "?" Again you have 5 days till it goes ready for harvest- RFH

-This means that you have FIVE days to attract/spot ALL animals for the given stage.NOTE : this is not applied to the whole 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.

-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 task.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.

-All 3/6/9... topiaries from one particular trail come out of ONE COLOR of pot.
For example for the red pot you can get :  Grey Squirrel,Skunk and regular Unicorn.
The orange trail is made of :squirrel,skunk,unicorn,meerkat,tortoise and winged unicorn

-The order of the animals you will get in a trail are completely RANDOM except the last one which is the new unicorn from that level.
NOTE that for the orange trail it is the winged unicorn NOT the unicorn from the red pot,which means you can get is just as much as the other topiaries.

-The number of animals spotted/attracted progresses through the levels as well as the number of stages in progressive mode of 3/6/9/12... and 2/4/6.. for the animals needed.You will definitely need to attract/spot the red/orange/yellow.. pots topiaries trails again if not several times to complete the higher level trails.(I will update later on)

-To trim a bush you need ONE REGULAR wildlife spotted in your garden (to see which one click on the "?" icon that says :Help! (Which wildlife will trim this Topiary?)" It is the  QUESTION MARK sigh on the bush when you hover your mouse on it)

STEP BY STEP GUIDE FOR RED POT (just to give you a clue 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 topiary till fill 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 :D

It will tell you what you need spotted in YOUR GARDEN and spot IN OTHER GARDENS to complete the fist stage of the red topiary trail just like the nests tells you which bird you need to hunt for.

Step 4.
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: Obviously, the more topiaries greater visit frequency.If you have lot of seeds you can do multiple topiaries at the same time.

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 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 (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,attract the regular unicorn,get it trimmed,speak to it again, complete the unicorn challenge (spot ONE and attract THREE topiary unicorns).
This time the bush stays same except that you can harvest it and move onto the orange pot.

When you complete the whole red trail you can buy the orange pot and start/repeat the same process except with more stages and animals need.In the pot shop you can find info about requirements for the yellow stage:

To unlock the Yellow Topiary Pot:

• Unlock the "Enchanted Black Mushroom"
[Details]

• Complete the Orange Topiary Trail
[Details:To complete the Orange Topiary Trail, plant a Topiary Seed in the Orange Topiary Pot and follow the instructions to complete all stages of the trail.]

• Complete 2 Red Topiary Trails (1 completed)
[Details To complete the Red Topiary Trail, plant a Topiary Seed in the Red Topiary Pot and follow the instructions to complete all stages of the trail.]

Based on this I conclude that we need to do the red trail twice and orange trail once to move onto the yellow stage.It is not necessary to buy 2 red pots ,you can redo the 2nd red topiary parallel with the orange one.But you need total 3 green seeds to unlock the yellow pot.When I get there I will update you again.

Good luck and don't forget to have fun :)))

Thank you so much this is most useful info to have.  Only one question one yr bush is trimmed to shape should you pull the plant to attract the critter needed to shape it??

Do extra suirrels/ skunks spotted in your garden over the required 3 carry forward and count to the next stage as with the butterflies do you know? Is it worth putting off spotting one in another garden and completing the trail until quite a few extras have been spotted?

-Yes rainbow rocks 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
-Yes it helps a lot to pull the plants that attract the critter needed to shape it as I stated in step 4 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
-Yep you can plant in advance -if you have space -if you are short on gems as no plant attracts anything if it is " growing happily"
-NO NOTHING THAT YOU SPOT/ATTRACT COUNTS BEFORE AND AFTER having bush trimmed in shape.As I explained through the instructions : "This means that you have FIVE days to 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.
-Thank you devs for moving my post to the "Most Useful Topics"  :))))))

I am now starting the 2nd stage of the first one (if that makes sense) but it doesnt give me an option to buy the next pot, I have to do this first stage all over again??

You have to complete all three stages from the first pot before you unlock the second one.

Tracey you have to complete it all twice (all 3 stages of the 1st one)

Not to unlock the orange pot you don't - that's part of the requirement to unlock the yellow pot.

its now given me the ability to get the second pot, so need to do 2 animals?