The facts are, growth times are only very slightly increased as now all plants grow-up at around 5am in the morning. Sheltered plants take 4 times as long, spliced plants now have a ridiculous 1/600 chance of producing the expected spliced result...I could give you many more facts but over all sounds like the other fansite simply has it wrong.
Plants now require to be fertilized 7 times before they will be ready for evolution and only if in Season (i.e. not sheltered as they take longer). So the changes to gardening have made reaching the Perfect garden very slow, and grindy. Sure you can now weed and water areas of effect but this only stops your sim from gaining gardening skill, so in my eyes, a negative.
The weed vacuum is not a real object in the game and never appears in your sims inventory, it is just magicked into your sims hands when they begin to weed an area of effect. Not a huge negative but previous iterations had this item as an upgradable object.
Plants need very little water now, (only once every 4-5 sim days) making getting the 10 plants weeded or watered at the beginning of the Botanist aspiration take sims weeks instead of a day if you don't plant a huge amount of plant in Season or sheltered immediately.
The Research Plant is often the only action your sim can take in the garden due to plants not needing as much care so instead of watching your sim weed, water and fertilize you now watch them spam 'Research Plant' repeatedly to level up - boring.
Plants at the most will only produce 6 harvetsables now with many plants always producing less than 5. Probably a good change now that plants in Season will grow produce a lot more often than before.
Interacting with a bonsai plant (build mode) will increase gardening skill but at a slightly lower rate than before as it now also gains florist skill.
A spliced longer growing plant will grow the same rate as the plant it is spliced to and will produce at the rate of the plant it is spliced to.
All of Carls timings are still correct but take into factor of simultaneous growth at 5am of each day so before perhaps the plant would have become fully grown at 7pm that night...now the game forces it at 5am (this is just a random example.)
http://www.carls-sims-4-guide.com/skills/gardening/Gardening has been radically changed ad although having bees nearby give a substantial boost towards decreasing evolution times as does an excellent fertilizer, it still takes a long time to grow that perfect garden.
Rotational players will struggle even on life setting long, a one household played game will struggle on live setting short. I'm not sure I'd hail the changes as great.
Carl's got a video out on this topic:
https://www.youtube.com/watch?v=6TYh_dxkwIQ