Daylily Care & Culture

Daylilies are tough, adaptable, vigorous plants that require less care than other perennials. Your new daylilies will grow and bloom for many years with no special care whatever. The cultural procedures given here apply generally to most perennials. However, if you are a daylily fanatic and want to see the best growth and bloom possible, pay close attention to their cultural needs.

Daylilies are classified dormant, semi-evergreen or evergreen. The American Hemerocallis Society refines this classification into hard-dormant, semi-dormant, semi-evergreen, evergreen and soft evergreen. These are described below.

Hard-dormant cultivars die down completely in the fall. This is a hormone-controlled event triggered by the short days and falling temperatures of the season. They tend to go dormant even in the deep south and to remain dormant until they have received about one month of temperatures below 40 degrees F. They stay sleeping until it is safe for them to wake up and start to grow. If they do not get their month of cold, they may not bloom or even die altogether after a few years.

Semi-dormant cultivars go dormant later in the fall and winter. They seem not to die down underground as far as do the hard-dormant ones and are ready to grow more readily with the advent of warm weather. This is an intermediate class.

Semi-evergreen varieties are both hard to precisely describe and controversial. Dr. Darrel Apps says, “I’m beginning to think that semi-evergreen is a lot like being semi-pregnant.” Many agree with the eminent daylily breeder. Certainly there is room for confusion here.
Evergreen daylilies remain green and growing the year around, conditions permitting. In the south, they grow continuously whereas cold cuts them down farther north. Despite this, many evergreen varieties do fine in the northern areas.

Soft-evergreen varieties need winter protection in the winter. This is far removed from the concept of the carefree daylily. These varieties are well adapted to the Deep South. Tenderness and evergreen foliage are independent characteristics and are inherited independently. Our advice is to observe the variety in question in a display garden or a friend’s garden where these characteristics have been evaluated. Reputable nurseries often state their policy towards selling of plants proven for a specific locale. Our policy is to sell only those varieties, which will survive winters unprotected in hardiness zone 5. We do not mulch or otherwise coddle our plants.

When daylilies are planted in part shade, they seem to bloom about two or three weeks latter than the ones in full sun. This is a trick to have a longer bloom period. Plant some in part shade and some in full sun, you have now increased your bloom period by three weeks.

They are not very fussy about soil, but a well-drained loam is best. Mix some organic matter into heavy or compacted soil at planting time.
The easiest way to assess your soil fertility and condition is to have a soil test performed. Soil test results give the right recommendations for fertilizer, compost, and pH adjustment. Aside from the soil test recommendations, there are only a few special procedures daylilies need for your culture to be perfect. The pH or acidity of the soil should be adjusted to the range of 6.2 to 6.8 ideally.
An inch a week applied in either rainfall or irrigation is perfect.

Daylilies should be planted at least two feet apart for large varieties and as close as twelve to eighteen inches apart for miniatures.
A hole large enough to accommodate the root mass should be dug. The crown of the plant (where the leaves and roots meet) should be planted no more than one half inch below the soil surface. Cover the roots with soil and water the plant completely. Remember to keep the cultivar name with the plant.

Daylilies do not generally have serious disease and pest problems. The few diseases they do have can be easily controlled by proper culture. Always pull summer mulch away from the crown at least an inch in early spring and again in late fall to prevent bacterial and fungal infection of the crown when sudden freezes damage the daylily foliage and crown. Freezing plus soil borne fungal and bacteria diseases cause "spring sickness" in daylilies and is difficult to treat effectively except by proper culture.

If chemical treatment is necessary, use a soil drench fungicide labeled for ornamentals. It should be applied twice about ten days apart. Some serious growers use a soil drench fungicide applied in late fall as a preventative. Fungal diseases causing spots on the leaves can be (but do not generally need to be) treated with a fungicide labeled for ornamentals and leaf spot fungi. Watering your plants early in the day when it is humid will prevent leaf spot fungi.

Aphids, thrips and spider mites are rarely a problem. Chemical sprays labeled for the particular pest and ornamentals will control them.

Any mulch used for other perennials can be used with daylilies. Mulch shades and cools the soil, helps prevent weeds from germinating and composts in place providing organic matter to the soil.
Pre-emerge herbicides like Preen or Treflan can be useful in preventing annual weeds from germinating in daylily beds. Grass-be-gone, Fusillade or Poast can be applied anytime the grass is actively growing to selectively kill invading grasses without harming the daylily.

Daylily clumps may be dug out of the ground and divided every three to five years since over-grown clumps may not bloom and grow well. Fall is the best time to divide in the south. Spring is the best time to dig and divide in the north since survival will be better. However replanting in the north anytime up to the beginning of September is acceptable. Vigorous re-blooming cultivars like Stella De Oro (and its many relatives) need to be divided and replanted every two or three years.

Clumps can be divided by washing all the soil from the roots and pulling two, three and four fan divisions off the clump. After washing, let the divisions dry in the shade for several hours or overnight. This lets cut surfaces heal and prevents fungal and bacterial infections. Replant the divisions as described above.

Most cultivars are as hardy and do not need winter mulch. However, even the "hardy as a rock" cultivars will grow and bloom better when given winter care. The first step is to make sure all summer mulch is pulled away from the plant crowns at least an inch. This is advisable for all perennials. Do not remove the old dead daylily foliage in late fall as the old daylily foliage acts as winter mulch.

If you have seen evidence of mice or voles, poison mouse bait scattered in the plantings is advisable. Winter mulch should remain in place from the time the ground begins to freeze all through winter until the middle of April in the north. In the south you may remove in mid February for zone 7. Then the mulch and old daylily foliage can be removed. Because spring can be early or late from one year to the next, a good rule of thumb is to wait until the soft maples and elms are in bloom before removing winter mulch in the spring. If winter mulch is removed early and a severe cold snap freezes new foliage, wait until it thaws and remove the injured leaves with a scissors. Newly purchased and newly divided daylilies should be covered with ten to twelve inches of winter mulch their first winter in the north.
Winter mulch definitely helps perennials survive winter. This is due to four factors. First, extra organic matter is added to the soil. Second, the winter mulch insulates plants from extremely cold winter temperatures. Third, winter mulch insulates plants from a warm January thaw. January thaws can warm the soil enough for plants to come out of dormancy and begin to grow. They are severely damaged when cold temperatures return. This is what kills many otherwise hardy perennials in the Midwest. Mid-winter thaws can also heave new plants out of the ground. Fourth, there is some evidence that perennials continue to develop new roots between the time the foliage turns brown and the ground freezes solid. This is certainly true for daylilies. Winter mulch extends the time before a solid freeze. Additional information can be found in the texts dedicated to daylilies and your local or state daylily society.

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