Answer: You didn't identify the plants so I don't know if they are annuals which can be quite short lived, or perennials, which should last much, much longer than yours seem to be lasting. Exposure to sunshine is key to plant health; plants that thrive in sun should be given lots of sunshine; those that like shade should be in the shade. Potted plants in full sunshine can not only dry out quickly, but if the pots are in direct sunshine, the roots can bake. So, if your potted plants like full sun, be sure to protect the pots from direct sun, but make sure the tops get the sunshine they crave.
Watering potted plants can sometimes be tricky. If soil gets overly dry, any water you apply can rush right out the drainage holes without actually wetting the soil. To overcome this, immerse the pots in a larger container of water every 10-14 days. Let it set for 10-15 minutes, until no more air bubbles rise to the surface. This will thoroughly wet the soil.
If you know the names of the plants you purchased, submit another question and we'll see if we can help with specific growing needs.
Q&A Library Searching Tips