I started doing what you said last year, that being said, I really can't help because I won't really know till the second year. Since tulips typically do well the first year, then decline. I planted both.

My only contribution is that I liked the look of tarda a lot better, the turkestanica wasn't as attractive. Which probably means it will do MUCH better over the long run (isn't that how things work?)

True. I am thinking I may buy both and see how it goes. It sounds like Tarda is shorter, so I will plant them a bit forward of the other species. I have had no luck with getting tulips to survive past 5 years. The only exception is the species type T.sylvestris. It has expended a bit every year, like a daffodil would. I also have about 3000 daffodils, only because they expand a bit and I dig them up and spread them out every 5 years or so. After 20 years, my 100 or so daffodils have climbed to 3000ish.

Yeah, I tried every likely tulip I could lay my hands on, including sylvestris (which I liked, being so cheerful). I can say (no surprise) that humilis and clusiana didn't like my location and didn't even make a return visit on 2nd year. I planted a mix from John Scheepers two years ago. The tarda/turkestanica was last year though.

I love Tarda tulips and wouldn't be without them. They are such a bright happy harbinger of spring for me and very hardy and long lived. They spread into nice patches over time. They produce lots of seeds which you can pot up if you are so inclined. I usually just sprinkle some onto the soil to germinate at will. They prefer sun (blooms close on a cloudy day) but will do ok in some shade. I grew turkestana at one time but found them to be lanky; I much prefer the shorter tarda.