Tarrant has been plagued by a hip injury since the late stages of the pre-season in February, consequently missing the Tigers' pre-season clash with Melbourne and their season-opening draw with Carlton last Thursday.
Speaking to the media ahead of his side's Round 2 bout with Adelaide, Hardwick clarified that the ex-Kangaroo isn't quite ready to take the field.
"Yeah, he's not right to go at the moment," Hardwick began.
"So, it's a little bit of a frustrating one for Robbie and us, we know he's a big, big boy that can play on those bigger type players like Tex (Walker) is down there (for the Crows), and Darcy Fogarty, obviously, but we've just got to make sure when he comes back into the side [that] he's right [to go].
"So he's probably, maybe one to two weeks away [from returning] at this stage, but we know that when he does become available that he's important to us."
Marlion Pickett, who was substituted out of last week's game, was done so tactically by Hardwick, as opposed to because of any injury concern.
Hardwick added that his squad was fortunate enough to emerge from Round 1 without any additional injury problems.
"Yes (we emerged intact), which has been good, obviously we've got our main training today, but, yeah, we got through unscathed last week, a couple of bits and pieces, but every side will be going through that, but we're fortunate we're starting to get a couple of those younger boys that were on the injury front back as well, which is also a positive.
Going into this weekend's contest at Adelaide Oval, Hardwick is wary of the Crows' best football, particularly after losing this same fixture in 2022, and after Adelaide surrendered a large lead to the GWS Giants in Round 1.
"We know when Adelaide plays their best, their ground (Adelaide Oval) lends to high-pressure [and] high-contest, they've got really dangerous forwards, and stoppage strength is an area of theirs that they didn't capitalise on last week (against the Giants), but they have previously, it's one of their strengths.
"We have a good understanding of what they bring and how they play and [Matthew Nicks has] got them going well and certainly got them going in the right direction, and they touched us up last year, so we've got to make sure we go over there and understand that this is a good side that have troubled us, and we've got to make sure we play our very best footy."
The Tigers are scheduled to battle the Crows on Saturday, March 25 (4:35 PM AEDT).