I think the thought against garden lights is while they are white and all around, they do not (or may not) meet the brightness / visible distance requirements, escpecially all night long...
Rule 22 - Visibility of Lights
The lights prescribed in these Rules shall have an intensity as specified in [Section 8] of Annex I to these [Regulations | Rules] so as to be visible at the following minimum ranges:
(a) In vessels of 50 meters or more in length:
(i) a masthead light, 6 miles;
(ii) a sidelight, 3 miles;
(iii) a towing light, 3 miles;
(iv) a white red, green or yellow all-round light, 3 miles.
(v) a special flashing light, 2 miles.