Water it whenever the soil around the roots is dry down about 2" - stick a finger in to the second knuckle and see. Don't do this on a rigid schedule, but according to the weather and eventual experience - if it's dry, water, if it's damp, wait another day or so. And don't just give it a quick once over with a hose - either use one of the soaker rings, or set the hose to trickle, and leave it there for half an hour or so - you need to apply the equivalent of 4-6 gallons of water, but very slowly, so the ground is wet to the bottom of the root ball. You also need to get the area you want the roots to grow into wet, to encourage the roots to grow out into it - if all the water is right next to the trunk, that's where the roots will stay. Don't rely on the lawn sprinkler system to do for a newly planted tree - it's not enough until the tree is established. Mulch will help keep moisture in the root area and will keep the soil cooler - mulch with any natural mulch (avoid the dyed ones, they look awful), no deeper than 4", as widely as you can (at least 3' diameter, 6' is better), and put no mulch in the inch or so around the trunk. You can smother the grass around the tree - which is competition for the moisture and nutrients - by laying down flattened cardboard or 4-6 sheets of black-ink newspaper layered with no gaps, under the mulch. Just make sure all the edges are covered, as the paper can wick moisture out of the soil if exposed to air. As an alternative, you can kill off the grass with Round-Up, but be SURE not to do this on a breezy day, so NO RU gets on the leaves. I fully agree with Jean001, above - taking a tree from a pot where it probably got daily watering, putting it in the ground, with a different structure, etc, which is a shock to it anyway, and NOT watering it is not a good idea. WATER for at least a year, tapering off in the second year, but water in long dry spells even in the third year.

I would not recommend Crepe Myrtles AT ALL they provide ZERO shade and are best used as a border tree for privacy and they grow Straight up and down even as a mature tree. I always shake my head when people plant these in their front lawns as they are going to be very disappointed. They are the WORST tree for shade and are on the most hated list for tree preservation groups because the cities always tries to pass these off as planting shade trees to meet quota. They are again only good for border trees and a punch of color not a shade tree AT ALL. I always try to warn people away from planting these in their front lawn.. ughh ..I would pick a Jacaranda every time just plant it close to the edge of your front lawn so the roots are not a problem and provide shade to your lawn and sidewalk. Also FYI if the tree roots rise which they shouldn't if planted deep enough and in proper planting sacks , the city is responsible for maintaining that tree in most cities. Within 5-15 feet in from the sidewalk most cities have responsibility for tree growth maintenance ie tree roots which is why I encourage people to plant as close the curb as possible. Consult your local tree foundations as to city responsibility to canopy within 5-15 feet.. Also while these trees are incredibly fast growing trees it will take some time before it ever becomes an issue if at all, we are talking decades.. by then your tree is most likely under protection of city tree ordinances. LUCKY YOU!

Laura: Jacarandas naturally grow as large shrubs and become trees only with training (removing all lateral branching) or with extreme age. And a good rule of thumb when planting ANY tree is to NOT prune the first year (and maybe mininmally, if at all, the second year). Let the tree establish itself. Leave the photosynthetic material (leaves) on the tree above ground so that they can make food for the tree below ground (roots). Once established (1-2 years), prune only for minimal aesthetic purposes. Of course, you'll always prune off broken, dead, or dying branches as well as, eventually, crossing branches or anything that reaches beyond where you want it to reach. And if you live in a slightly windy area, also prune the tree to be more open to allow wind to blow through. Joe

@ Sari Swede I guess it's good as is where You live. You can make a little shelter for the plant for the unusual cold winter days, but maybe it's not necessary. The roots are at least 10-12 inches (or more) below the ground and they will never be under 45F. Even if the leaves frost, the roots will be fine. Anyway it's not a bad idea to pour some wood chips around the trunk as a thermal insulation. Jacarandas drop almost 90-95% of their leaves in the winter. Just a few remain. As for the pruning: the best time to prune the Jacaranda is late winter. I usually prune mine in January. Make sure that the tool is clean you prune the Jacaranda with! Jacarandas are sensible to infections. Wherever you cut, it will branch out 2, sometimes 3 ways! Jacarandas usually bloom first when they reach 3-4 or so years of age. The tiny buds will appear in september-october and they will "sleep" during the winter. In spring the Jacaranda blooms even it has no leaves! Beautiful sight and very good smell! So You have to be careful with the pruning, because you can cut the tiny buds off when prune your plant and it will not bloom in the spring. But it's a bit far away now, you have to wait for the first buds 2-3 more years. Good luck!