If your oversize crops are sparkling, then that is probably from the fertilizer. It does wear off after about a day so you know to fertilize them again. It does take time for them to grow and get to the point where you can harvest them so you just might have to wait a few days. Oversize plants don't evolve.
For the regular garden plants, it takes various amounts of time for each to reach the point where they can be evolved depending on what plant it is. For some plants it seems to take forever and others are ready to evolve sooner. You can tell by mousing over one and looking at the evolution bar in the tool tip. A segment must be full before you can evolve the plant. Until then, the evolve option won't show up or will be greyed out. The plant will sort of sparkle when it reaches that point and you should get the evolve option. If you have the Bust the Dust pack and have your garden in an enclosed space with a floor like a basement, the sparkle from a clean floor looks about the same as that on a plant ready to evolve so sometimes it is really hard to tell if the sparkle is from the floor or the plant.
You only get the harvest option on the plants once they are fully grown. That takes a few days depending on the plant. All the regular plants bear beginning at 5 AM everyday and reach the full harvest amount by 5:30 AM. You must be active on the lot at that time for the plants to bear. If you are traveling off the lot at that time, you get no harvest at all. The 5 AM also applies to the wild plants out in the world but only for the zone you are in at that time.
That said, I have seen an issue in my game where I do not get the harvest option on plants that appear to be showing their harvestables. But those plants are out in the world in the planters and pots like in New Old Hensford, not on a lot. I've also seen it at the City Life festivals. So I think there may be an issue with those atm.
Hope this helps.
