The Nikon D3500 sports an APS-C size image sensor. This sensor measures 15.6mm by 23.5mm. Lenses for any format revolve around the corner-to-corner (diagonal measure) of the camera’s imaging chip. For this Nikon, that dimension works out to 28mm.

If we mount a lens with a focal length about equal to the diagonal, this lash-up delivers a “normal” view. ”Normal” means, not wide-angle and not telephoto. In this instance, if you mount a “normal” lens of 28mm, the angle of view with the camera held horizontally will be about 45°. If your goal is to image flower arrangements, your best bet is likely to mount a “normal” lens.

Now a fixed focal length lens, in the jargon of the photo industry is labeled “prime”. The word “prime” implies best quality. No one will dispute that prime lenses deliver; however, the trade-off is reduced versatility.

The Nikon D3500 is generally sold boxed (kit) with a zoom lens. A zoom lens provides flexibility in that the user can alter the focal length easily. Thus the kit lens commonly sold spans the focal length range of 18mm thru 55mm. Note that the center of this range falls within the “normal” range. As a general rule, 70% of “normal” is considered the beginning of the wide-angle range and twice “normal” is the beginning of the telephoto range. What I am telling you is, your kit lens was intentionally configured so that, right out of the box, you have what you need. In other worlds the kit lens delivers a good introduction to the world of imaging.

You already have what you need for the task you asked about. The question is, will this lens deliver the needed acuity? The answer is, yes, it is unlikely, for the task you outlined, to ever need better. If you have deep pockets, you can go crazy buying primes and macro zoom lenses.