The same plant during a cloudy, cool period may not require water for 2 or 3 days. Don't allow the plant to wilt. Some plants can come back from severe water stress with no problem, but the majority of plants will not. When watering, water thoroughly so that water drains from the bottom of the basket. If the plant has been allowed to dry excessively, place the basket in a bucket of water for an hour or so to return the moisture supply to the potting mix.
Fertilization is also very important.
The root systems of container grown plants cannot go out in search of food so it must be provided on a regular basis. Several fertilizer forms are available. Select the fertilizer form that works best for you and follow label directions for application rate. Fertilizers that are higher in nitrogen will produce vegetative growth rather than flowers. Deadheading is necessary to help flowering baskets blooming well.