Perennial Care:
Native species will grow slowly at first since they are putting most of their energy into their substantial root systems. Because of their substantial root systems native plants need no watering once they are established and are very hardy. However, “baby” plants need a little more care to get established. Larger gallon-sized plants can often be showy in the first year they are planted, but smaller quart and 2.5" plug-sized plants will take at least a season to get established before they start to show off.We recommend watering the plants extremely-heavily every-other day for the first two weeks after they are planted if mother nature doesn't take care of this for you. By "extremely-heavy", I mean you need to water them to the point that you are sure you are drowning the plants, then continue watering for a while longer! By doing this, you are saturating the soil column several feet down, and encouraging deep root growth to follow that water down into the soil. By taking a day off between these heavy waterings, you give the surface soil some time to dry out to be sure enough oxygen is getting to the roots to avoid rot and to promote optimal growth.
Be sure to avoid run-off with this very heavy watering. I usually just rotate the watering around the planting bed as I am watering, moving from one area to another as each gets saturated and starts to form puddles. Once the puddles drain, I return and saturate the soil there again, and repeat.
Also water the plants during any prolonged dry spell during their first growing season. A lack of significant rainfall for a full week constitutes a "prolonged" dry spell. Look for the leaves on the plants "flagging" as an indication that they are drought-stressed.
If you wish to accelerate the establishment of your plants a bit, you can water them regularly throughout the first growing season.
Weed your planting about every 2-4 weeks during the first two growing seasons, as needed. Muched perennial plantings don't require much weeding at all for the first year.
Trees & Shrubs Care:
Any tree or shrub will need lots of watering in its first year of life. Larger plants that come in the 'ball and burlap' (B&B) form are especially sensitive since so much of their root mass, particularly their fine roots, were cut-off when these plants were dug from the ground at the nursery. For this reason, we prefer to plant smaller woody plants that come in containers whenever possible, or some larger trees (up to 1.5" caliper) are now available in root bags and these are much hardier than equivalent B&B plants.Any tree species is also going to be sensitive to dry soils since their root structure (which focuses on large, permanent roots) is less adaptable than that of a shrub (which tend to have smaller roots that can be replaced more easily).
As a general rule, trees less than 1” in diameter (or shrubs of equivalent size) or less will only need watering for the first growing season they are in the ground. For each additional inch of width, you should water it for one more year. I'll call this time period based on plant size the supplimental watering period. So a 4” caliper tree will have a supplemental watering period of four years installation. This is another good reason to choose a smaller plant to begin with. Typically, shrubs in 5-20 gallon containers will only need watering during their first year on site. These small plants also grow faster than larger plants which suffer more from "transplant shock" and often halt growth for a year or two after planting.
No matter what size plants you have, watering should be done frequently and intensely. For the first two weeks after planting, we recommend the same watering regime for woody plans as we do for perennials: water extremely-heavily every other day for two weeks, as described above. This is probably the equivalent of 6"-8" of rainfall for each of those first two weeks.
Once the young woody plant has been in the ground it will be slightly better able to handle drought stress so you can back off a bit. A good rule of thumb for any tree or shrub is that they will do best with the equivalent of 2” of rainfall a week during the entire supplemental watering period, whether provided by you, or the weather. If you are using a sprinkler to water your plants then leave out a small container in the area, and once it fills up with water 2” deep, you can turn the sprinkler off. Soaker hoses help reduce any leaf mildy issues that can arise from frequent use of a sprinkler, and are generally more efficient uses of water but are more difficult to monitor. Remember, you are trying to saturate the soil in the entire area surrounding the plant, but also, giving the soil time to drain between watering.
Weeding is less necessary for tree and shrub health. However, weeds often come in the pot with the plant, so check them a few times in the first growing season or two for dandelions, thistles and various biennial weeds such as foxtail grasses.