Since this is your livelihood, it is permitted without any hesitation. This is because if you were to say that you do not wish to perform gardening work during this period because Halachah forbids it (under the law of “joyous planting”), you might be fired, and consequently, it is permitted. However, even in this case, a distinction must be made: anything aimed at maintaining the status quo, such as weeding and the like, is permitted even during the week in which Tisha B’Av falls (Shavua SheChal Bo), whereas the prohibition applies specifically to planting and introducing new growth. Therefore, you may continue your work until the week in which Tisha B’Av falls, and during that week, you should engage only in maintenance work and not in development work.

Nonetheless, from the municipality’s perspective, one should approach the supervisor and state that care should be taken to cease all environmental development work starting from Rosh Chodesh Av and focus solely on maintenance. Furthermore, if you tell your employer that you cannot work from the 17th of Tammuz onward in planting and the like, and you will not be fired, you must be careful regarding the matters we mentioned as a matter of actual law, not merely as a stringency.