Growing Daylilies

Some Considerations on Crown Rot

GROWING DAYLILIES in 2003©
by Clarence and Beth Crochet

Daylilies come in many colors – “near” white, pink, orange, gold, lavender, purple and the darkest red. There are several forms also – single flowered, double flowered, small flowered, miniatures, polytepals, variants, spiders, and unusual forms. The last three types have narrow segments (petals and sepals). There are also various foliage and scape (stem) heights.

Planting daylilies can be done at almost any time in South Louisiana, but it is best to plant either in the spring (March, April, and early May) or in the fall (October and November). The weather is not too hot during these months. If planting is done at other times, it will be necessary to provide special care for the plants. Shading for two or three weeks is a good practice and by that time, the plants will have begun to “green up” and the shade can be removed. Plants should not be over watered while they are establishing their necessary new root systems. Damp soil is preferred. All plants to be planted should have their foliage cut down to 5-6 inches high.

Daylilies grow well in many types of soils. They also benefit greatly by being grown in soils that are well drained and which contain a good amount (about 20%-25%) organic matter. This can be composted cow or horse manure, compost, composted pine bark mulch or other composted organic material.

In South Louisiana, it is almost a necessity to raise daylily beds above the surrounding soil surface. Do this by adding coarse sand if the soil is mostly clay. It is necessary to use accompanying organic matter with any addition of sand or soil. This mixture should be tilled into the soil to a depth of 10-12 inches or more. The minimum depth should be 8-10 inches.

The prepared soil should then be checked for its PH reading, or better, a soil sample should be prepared and brought to the County Agent so that he can send it to the L.S.U. soil lab for analysis. Daylilies like a PH of about 6 to 6.5.

When planting, daylilies should be spaced 18 inches apart to allow for plant increase. All leaves and scapes must be cut to 5-6 inches above the crown before planting. This is necessary because tall, uncut leaves will dry up anyway. If left uncut they will tend to sap the energy from a plant that is trying to establish itself. Plant so that the crown of the plant (where the roots meet the leaves) is just under the soil surface. One should describe a mound on the soil surface, place the crown on the mound, and cover the roots, being careful not to plant too deeply. If the soil is normally damp (not too wet or dry) watering is not necessary for 8-10 days. By this time the plant will have begun to “green up” and show new leaves emerging from the middle of the plant. If needed, this is the time to water.

Water plants regularly in dry weather. One inch per week is usually sufficient. It is necessary to remember that daylilies like water, but they don’t like wet feet!

A year round mulch for daylily plants is very desirable. Five or six inches of pine needles, new bagasse, pine bark mulch, seedless grass clippings, or seedless grass hay will protect the plants from freezing if applied in the fall or early winter. Mulches also inhibit weed growth and help to conserve soil moisture.

Daylilies are usually fertilized when active growth begins in the early spring. For us, this is usually near the end of February. They require a regular application at this time. A good grade of a balanced fertilizer with minor or “trace” elements is best. Plants should also be fertilized in the fall, using less fertilizer. There has been renewed interest in the last few years in using water-soluble fertilizers for daylilies. This is the fastest acting method. Liquid fertilizers should be used in the early spring and at other times when the weather is still not too hot. The new “time release” fertilizers are a vast improvement over what was once available a few years ago. Two of them are “Nutricote” and “Osmocote.” Osmocote is available at most well stocked nurseries and large “chain” stores. “Nutricote” is more specialized and might be more difficult to find, but the results from its use are worth the effort because the fertilizer is slowly released, avoiding plant “burn.” “Nutricote” also releases its fertilizer according to temperature. Both of these fertilizers also contain the trace elements necessary for good plant growth. Another excellent fertilizer for early spring application and for incorporation into fall bed preparation is Millorganite, an organic granular that will not burn plants. Check for it at the big home/building centers and garden centers.

Like most plants, serious plant pests can attack daylilies. Among the most common is the daylily aphid. This tiny soft-bodied insect likes to suck the juices from the new leaves in the center of the daylily plant. Aphids will attack during cool weather. Spraying with Malathion or Cygon 2E can control them. Cygon 2E is a systemic insecticide which provides an extended protection period.

Mature thrips are tiny winged creatures. They usually attack daylilies in cool weather and will suck the juices from the immature scapes and destroy all of the buds while they are near the ground and under the mulch, resulting in deformed buds and blooms. It is best to begin to spray for thrips during the cool early spring months to keep them under control. They can be easily controlled with the use of Cygon 2E.

Spider mites attack daylilies under their leaves, sucking the juices from the plants. These mites look like very tiny spiders. They also make webs under the leaves. One way to find out if daylilies are being attacked by spider mites is to hold a white sheet of paper under the suspected leaf, tapping the leaf with the thumb. If mites are present, they will fall on the paper and move around. A good magnifying glass is also a very good way to identify mites. Mites can be best controlled with “Avid”. There are also other miticides. But the product “Kelthane” (often suggested by retailers for spider mites) or other products containing “Kelthane” should NOT be used on daylily plants because this product will seriously damage the daylily plant.

Slugs also attack leaves and blooms and can be eradicated with slug bait. Avoid pine bark chuncks.

Rust (Puccinia hemerocallidis) has recently been found in the U. S. This fungus is becoming widespread and at this writing it is believed to be easily dispersed by the wind and even by human contact. The rust manifests itself as small black dots on the underside of the leaves of the daylily plant. These dots mature and turn bright yellow-orange in color. The rust will damage the leaves severely if it is left unchecked. There are several kinds of fungicides available at both retail garden stores and at wholesale distributors. Two fungicides, which are available at most nurseries and large retail stores, are “Daconil” and “Fertilome Systemic Fungicide”. These are contact fungicides used as a spray and are applied to daylily leaves every 7-10 days, while being careful to alternate them. Other fungicides, which show promise, are “Quadris” and “Heritage”. Both are systemic fungicides that seem to be effective at controlling rust. “Bayleton” and “Tilt”, systemic fungicides, have also been effective at controlling rust. A surfactant or “spreader sticker” should be used with each fungicide application. For use as “spreader/stickers”, dishwashing liquids are also effective and are less expensive. One thing seems certain - daylily rust is probably here to stay, just as black spot on roses. It will be a problem for plant scientists to discover an effective, long lasting solution to the rust problem. Rust research is being done at this time and it is likely that more and better systemic and contact fungicides will be developed as more is learned about the problem.

Clarence and Beth Crochet

Crochet Daylily Garden

P.O. Box 425

Prairieville, LA 70769

Some Considerations on Crown Rot in Daylilies

by Clarence Crochet

Crown rot is rather common in our area, and we believe that bacterial crown rot is the more prevalent of the two kinds. The other kind is fungal crown rot. It can also kill daylily plants with ease if steps are not taken quickly to prevent complete plant loss. Both kinds are prevalent during warm or hot weather.

Bacterial rot is noticeably bad smelling-like rotten onion. It can reduce daylily crowns to a slimy, soft mush. It can be prevented from attacking the plant by dusting with Rootone F. This is a growth-promoting substance with added fungicide. The material is applied with a small artist paintbrush on any cut surface around the daylily crown before planting. In effect, Rootone F does two things: it greatly reduces the possibility that bacteria or fungus will attack a newly cut plant. Secondly it promotes the fast healing of the cut. We are careful in handling Rootone F and all that is needed on the cut place is a light dusting of the material.

Another highly effective material for rot is Tetracycline. This substance is at least as effective as Rootone F and might be even better because it is water-soluble and a good soaker for new or expensive daylily purchases. This material is available from veterinarians. It will kill soil-borne bacteria quickly. The technique for using Tetracycline is to apply it as a drench around planted and growing daylilies which show some signs of bacterial rot because of the yellowing of plant leaves. In this instance, it is important to wet the base of the plant well with the solution. The Tetracycline proportion is one level teaspoon to one gallon of water. Applications can be repeated at weekly intervals.

In order to prevent as much damage as possible to our cultivars from fungal rot we are careful to dip newly purchased (and often expensive) plants in a good fungicide and let them dry completely before planting. One good choice of fungicide is Daconil. It can be purchased at most well stocked nurseries or garden centers. It should be remembered that there are two kinds of Daconil. One is a liquid and another is a powder. Folks who grow daylilies around here say that the powder form is the better one.

It is also possible to save an affected plant by digging the plant immediately after observing that it is yellowing. The plant must be thoroughly dried and the soft spot around the crown cut off with a sharp clean knife. This means that the crown is also cut or gouged until all of the affected plant tissue is removed. It is easy to tell the affected tissue because it is of a different color from the healthy part of the crown. This doesn’t matter, as most plants will make a quick recovery by producing new growth in the form of one or more small plants around the cut area of the crown. It is important to save at least some of the crown because this is where the new plant will originate. Plants treated in this manner are dusted with Rootone F and potted in good, well-drained soil, which has been amended with coarse sand. This helps to provide good drainage.

One of our theories is that when nematodes are present in our soils and when they damage roots or crowns on daylilies that damage will allow bacteria or fungus to attack the plants, thus causing “crown rot.” In the past we have saved valuable daylily cultivars by treating them immediately.

Crown rot, like rust, will be with us so it is in our best interest to attack it as we have with Puccinia hemerocallidis. It then becomes our job to spot early trouble in our plants and take the proper steps to save them.

CJC