Answer: Daylilies (Hemerocallis) generally bloom best when grown in full sun in average to rich soil that is kept evenly moist but not sopping wet during the growing season.
An annual application of an all purpose granular fertilizer such as 10-10-10 done according to the label instructions in early spring should be sufficient in average or better soil; you may use the water soluble types instead of the granular but again, follow the label instructions. It is important not to overfertilize because this can cause excessive foliar growth at the expense of blooms as well as make the plants susceptible to pest or disease problems as well as overly lush growth will suffer extra moisture stress in times of drought.
Probably the most common reason for lack of blooms is lack of sunlight. These plants really do best in full sun all day long or at least six hours of sun including the hour of noon.
Another possible reason for decreased blooming is that the plants need to be divided. Daylilies can usually be left as is for between three to five years, but if you planted very large plants at the outset, they may need it already. This can be done in early spring, late summer or fall.
Some varieties of daylilies, especially among the "everblooming" types, may benefit from being divided as often as every other year for best performance. (Some gardeners will divide these every year to stimulate new growth and consequently more blooms.)
Finally, insufficient soil moisture is another reason they may not bloom the way we would like them to. Although somewhat drought tolerant, these plants really do prefer ample water during the blooming season. When you water, water deeply and make sure the water soaks down deep to the roots. (A daily light sprinkling is much less effective and also uses more water in the long run. Use your finger to dig down into the soil and see if you need to water.)
Use several inches of organic mulch such as shredded hardwood bark to help moderate the the soil temperature, maintain a more even moisture level and also help keep down weeds. It will also help feed the soil on an ongoing basis as it breaks down over time.
I hope this helps you trouble shoot.
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