Summarize the following:
Daylilies are drought-resistant, but they bloom best when they have moist soil. Water them in the morning or evening once each week. If your daylilies are planted in sandy soil, you may want to water them twice a week to ensure their soil stays moist. Over-watering can cause crown rot, so be careful. Avoid watering daylilies during the midday heat. Fertilizing lightly each spring after the initial planting will boost their growth for summer blooming. Use an extended release fertilizer for best results. Other than that, you can use any kind of fertilizer you want as long as it's relatively low in nitrogen. Daylilies don't require winter mulch, but they will appreciate an organic mulch during the summer. They aren't very particular about the type of mulch you use, so feel free to experiment. Take care not to cover the crown of the plant with mulch. Straw, grass clippings, and leaves are all good choices for mulch. Summer mulching helps the soil retain water and lowers the soil temperature during the hot summer days. Mulch also helps crowd out weeds. Daylilies are quite resistant to most pests, but spider mites can sometimes be a problem during the hot and dry summer months. If you see any spider mites on your plants, simply rinse them away with a forceful spray of water. Check the plants frequently and repeat the rinsing, if needed. If the mites are particularly tenacious, you can also use an insecticide.

Summary:
Give daylilies 1in (2.5cm) of water each week. Fertilize daylilies in the late spring. Mulch your daylily plants in the summer. Watch out for spider mites during the summer.