Yes, you can attach an urban planter box to a brick wall without drilling, but only if the planter is small and lightweight and you use an exterior-rated no-drill mounting method. The key issue is not whether it can be stuck to the wall; it is whether the connection can safely hold the planter when the soil is wet, the plants grow, and wind pushes against it. Wet potting mix is much heavier than dry mix, so a box that feels light at installation can become a serious load later.
For a truly no-drill installation, the most realistic options are high-strength exterior construction adhesive used with a purpose-made no-drill bracket, or an adhesive-backed bracket system designed for outdoor use. These are suitable for compact boxes with succulents, herbs, or small seasonal plants. They are not suitable for large timber or metal planter boxes, deep soil volumes, or anything mounted high above a walkway. Avoid ordinary removable adhesive hooks and indoor foam tapes; they are not made for outdoor weather, UV, moisture, or long-term loads.
Prepare the brick surface carefully. The wall must be clean, dry, sound, and free of loose mortar, dust, efflorescence, or flaking paint. Mount onto the brick face rather than crumbling mortar, and follow the adhesive manufacturer's temperature and cure times. Use a drip tray or design drainage so water runs away from the adhesive and does not stain the brick. A safety tether can add peace of mind, but it should not be used as a substitute for a proper load-rated fixing.
If the planter is medium or heavy, or if you want a long-term, worry-free installation, drilling is usually the safer choice. Masonry anchors set into sound brick—installed correctly and sealed against water—will outperform adhesive-only mounts. For rented or heritage brick, consider alternatives that do not load the wall at all: a freestanding planter stand, a floor-standing trellis, a balcony rail system if one exists, or a lightweight box supported from below.
In short, yes, no-drill brick-wall planter mounting is possible for lightweight urban planter boxes with the right exterior adhesive or no-drill bracket, but it is a weight-limited solution. Check the combined weight of the box, soil, water, and plants; choose exterior-rated hardware; test the adhesion; and move to mechanical fixings or freestanding support if there is any doubt.