Planting and Growing Bulbs Instructions

Planting and Growing Bulbs

Preparing Soil

Properly preparing the soil for bulb planting is important. Good soil drainage is essential in raising bulbs. If you have a soil with a high clay content, it can be improved by adding compost, peat moss or some other source of organic material. The organic material should be worked in the top twelve inches of soil (eighteen inches is even better).


Both spring and summer bulbs need phosphorous to encourage root development. Keep in mind that phosphorous moves very little once applied to the soil. Some bulbs are planted 6 to 8 inches deep. The phosphorus needs to be mixed in the soil below where the bulbs will be located so it can be utilized by the bulb roots. Mix bonemeal or superphosphate with the soil in the lower part of the planting bed as it is being prepared. If bulbs are going to be maintained in a planting bed more than one year, it is important to supply additional fertilizer. Spring flowering bulbs should have mixed into the soil in the fall five tablespoons of 10-10-10 soluble fertilizer (or equivalent bulb fertilizer) plus two cups of bonemeal per ten square foot area. As soon as the shoots break through the ground in the spring, repeat the above soluble fertilizer application. Do not fertilize spring flowering bulbs after they have started flowering. This tends to encourage the development of bulb rot and sometimes shortens the life of the flowers. Summer and fall flowering bulbs should be fertilized monthly from shoot emergence until the plants reach full flower. Apply seven tablespoons of 10-10-10 soluble fertilizer (or equivalent bulb fertilizer) split over two or three applications over a ten square foot area. The optimum pH range for bulbs is 6 to 7. A soil test of the planting area is necessary to determine if lime needs to be applied to adjust the soil pH. If needed, limestone should be worked into the soil. For good bud development, work bonemeal into the soil at planting.

Planting Depth

The general rule of thumb for planting spring bulbs is to plant two to three times as deep as the bulbs is tall. This means most large bulbs like tulips or daffodils will be planted about 8 inches deep while smaller bulbs will be planted 3-4 inches deep. Planting depth is measured from the bottom of the bulb. This rule of thumb on planting depth does not apply to summer bulbs which have varied planting requirements.

Watering Bulbs

Water the bulbs following planting. This will help settle the soil in the planting bed plus provide needed moisture for the bulbs to start rooting. Fall planted bulbs must root before cold weather. Avoid over-watering at planting time since this can result in bulb rot. For both spring and summer bulbs, start watering when the flower buds first appear on the plant if the soil is dry. Shallow watering will not do the job. Remember that the bulbs may have been planted 6 to 8 inches deep and the water needs to soak to that depth. Through the bud, bloom and early foliage stage, add about one inch of water per week if this amount has not been supplied from rainfall. Water with a soaker hose to keep water off the bloom. Bulbs like alliums, or the shallow planted bulbs, will rot quickly if over-watered in the heat of summer.
One of the visual problems with spring bulbs is the foliage that remains after bloom. The foliage can become unsightly if the bulbs are planted in a public area of the landscape. Foliage should not be mowed off until it turns yellow and dies back naturally.