Daffodils are Soil Conscious

Little-known facts about growing daffodils in hot climates… Daffodils are Soil Conscious

Daffodil may be a “dilly” when soil and climate please her, but when conditions are not to her liking, she fades out of the garden picture.

Few gardeners expect a trumpet daffodil to be as soil conscious as an azalea, because current garden books fail to mention this fact. Over 65 years ago Michigan State University, compiled a “Soil Preferences of Plants Bulletin” stating that trumpet daffodils thrive only in a narrow soil pH optimum range of 6.0 to 6.5. The pH scale is a scientific way of showing acidity or alkalinity. A pH of 6.0 to 6.5 is a narrow range slightly on the acid side. As the trumpet daffodil classification also includes the small and large cupped kinds it takes in the greater number of popular daffodils.

However the bunch flowered narcissus, N. Tazetta, of which paper-whites, and other hybrids are representatives, is as soil tolerant as a zinnia, thriving within an optimum soil pH range of 5.5 to 7.5 - from quite acid to rather alkaline conditions.

Considerable time and money will be saved if gardeners choose bulbs that will grow in their respective gardens. Aside from the pH soil factor (which may be learned by soil testing) common sense dictates that bulbs be planted in soil that is well drained and not so heavy that it will stick to bulbs at digging time.

Ripen Too Soon

Soil acidity or alkalinity is not the only important growth factor in daffodil culture. In the South where high temperatures and drought occur yearly during July and August, we find that daffodils take on a bad behavior pattern unheard of in the favored bulb growing climates of Oregon, England and Holland.

In this climate the first season after planting a top size bulb gives a top size flower. Thereafter the flower is medium size. What causes it is this: the foliage does not have a normal time to mature and store up carbohydrates for bulb welfare. In Tulsa, daffodil foliage is ripened by June 1 while in Oregon the foliage is retained until August 1 and in Holland until August 15. That is why bulbs as large as those grown in Oregon and Holland cannot be grown in a southern or hot climate.

Another factor that is not natural for daffodils is that in the South daffodil bulb roots dry off beginning in July and stay dormant until fall rains come, sometimes as late as November. In cooler climates although the bulb foliage matures, the bulb roots continue growing and the longest period without root growth for any daffodil is two weeks. That two weeks dormant period in cool climates compared to almost four months dormancy for a daffodil in our southland, certainly is one reason why cooler climates are better for daffodil growing.

Heat Hurts Buds

We also find daffodil bud formation which occurs after daffodil foliage matures, inhibited by hot soils. If the soil temperatures at bulb depth go much higher than 75 degrees for a week or two, bud formation is killed. In the Chicago area fellow flower gardeners have been able to prevent bulb blindness by deep planting, that is, eight inches of soil over the tops of bulbs.

In the South deep planting does not always suffice to cool the soil enough for bulb bud formation, and we are forced to use mulches. Mulching daffodil bulbs in private gardens is one to two inches deep.

Cause of Splitting

We also find that hot soils during summer cause daffodil bulbs to split. Too much nitrogen does the same thing. When food storage passes a certain minimal requirement, then that supply is capable of supporting a larger population than the single bulb. As a result some mechanism within the bulb goes to work and it splits to form new individuals to take advantage of the food in excess of normal needs. This is the reason that daffodils do better in soils on the poor side than those high in nitrogen.

Greater difficulty in getting white daffodils to flower than yellow ones has occurred too consistently to be passed over lightly. In my experimental garden where I have raised thousands of daffodils since my first planting 35 years ago, white trumpets have flowered when watered daily during summer, and in winter, if a dry period occurs.

The explanation for the non-flowering of white trumpets may be that they make their buds as late as July when daily temperatures near 100 degrees are common. Yellow trumpets bloom here (Oklahoma) from mid-February and seldom as late as early April as some white varieties do. That means that yellow trumpets make their buds when dormant in June, our rainiest month.

Even if daffodils grown here are not as large flowering as in moist climates, still they require little in the way of care other than poor, slightly acid, well drained soil. Neither the iris nor the rose gives such a long period of bloom as does the daffodil which welcomes spring in February and ushers in May flowers.

by L Quinlan

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