New gardens need a good watering right after being planting. Make sure to soak the entire ground right after the intial planting. If dry mulch was added around the plants, it may take some time to soak the mulch before getting to the soil around the plants. If it is hot and sunny they should be watered again the next day. The first week will need the most watering every day or 2 but making sure the ground is not soaking, just staying moist. After the first week you will know when its time to water if you see the first signs of leaves starting to droop, wilt, or of the ground below the mulch is dry, then it is time to give the garden a good watering.
It is a good idea, NOT to water your garden everyday and to let your plants get to the early signs of the wilting stage before watering. This helps the plants develop a strong root system as they dig down deep looking for more water. If you water every day, they have no need to do that and will stay at the surface. The stronger the root stystem, the longer plant life you will get, you will save more water, they will survive better throughout the winter, and they will grow larger.
MULCHING
Having 2-4" of mulch around the base of the tree will help retain soil moisture, moderates soil temperature, and helps keep grass and weeds from creaping in and stealing nutrients from the new plantings. Mulch is an organic matter that breaks down over time and adds good quality nutrients to your soil. Be sure to leave a small ring around the trunk of your tree to avoid decay from moisture.
Not having enough mulch, where you can see the ground through it, does not help, it will dry out to quickly, will not hold moisture, and will not stop grass from creaping in. The extra money in having the 2-4" of mulch will really help over the lifetime of your plants. Too much mulch may stop oxygen from getting to the soil and may soak up all of the water from reaching the roots.
COLLECTING RAIN WATER
So you have a new garden and are using a lot of water. A good way to re-use, and save on your water bill, is to use rain water. A simple easy way to to do that is to make a rain barrel from a large, round plastic garbage can you can pick up from a local hardware or retail store. cut a hole about 4" in the center of the lid, turn it upside down and place it on top of the can. Place the can underneath of your rain spout.
This can also help if you have issues of rain water in your yard where it just is not draining properly and is pooling on your sidewalk or in your front yard.
Collect the water in the garbage can and then use a watering can to spread the water on your garden. You will save in more ways than one!