You can water landscaping put in by your landscaper so long as they are licensed and you are watering between midnight and 10am. If they are on the property they can do the watering at any time.
If you planted your own landscaping prior to 9/28 you are exempt and can water between midnight and 10 for up to 30 days from date of purchase. Better have a receipt.
If a service similar to chemlawn applies some unnecessary lawn chemical to your lawn and says to water it in then you can water your lawn between midnight and 10 am. Be sure to have documentation or a receipt. This is exempt under the 'activities essential to daily business'. And YES you can go into the plant/landscaping watering business although there are some guidelines as to how and why plants may be watered.
You can use water that you sucked out of a pond or stream but it advises against doing this because said sources of water won't fill up to soon.
You can collect water from your shower "while the water is heating up"
You can water in pesticide and herbicide (Does not specifiy if this must be done midnight to 10 but I would do it then)
Food gardens of course. The regulations do not differentiate between edible fruit trees such as Autumn Brilliance Serviceberry and herbs. It does exempt "fruit and vegetable growers".
Pressure washing. Pressure washing is useful for washing cars but does not put out enough water to efficiently water landscaping unless you want to burn through a lot of gas and make a ton of noise. It doesn't say what you can or cannot pressure-wash.

Disclaimer: This posting is not intended to be legal advice. If in doubt consult the regulations or contact a lawyer but don't come back and blame me. The regulations are subject to change. Prices and participation may vary. If you experience dizziness or light-headedness, discontinue watering and consult a physician.