Can Grass Kill Tulips?

Proper Planting Technique

• In general, tulip bulbs need to be planted at a soil depth that equals three times their width or slightly more distance. For example, bulbs about 2 inches wide need a 6- to 8-inch deep holes in the lawn in order to have the best growing conditions. If they are planted extremely deep or too shallow, tulips fail to flower. Avoid damaging your turf by carefully cutting out a circular grass patch to access the soil below. Once you position a tulip bulb in the hole and cover it with soil, gently press the turf patch back into place. The grass will recover quickly, and the tulip sprout will push through the soil and grass easily to access sunlight in late winter or early spring.

Root Competition

• Grass roots, such as those of many cool-season varieties, tend to stay in the upper 6 inches of soil, where the majority of nutrients, moisture and oxygen are abundant. Because tulip bulbs perform best with a 6- to 8-inch deep planting depth, their roots extend deeper than grass roots, and the bulbs and grass roots do not compete for limited natural resources. Both kinds of plants grow easily together without negative effects.

Soil Compaction

• Turf can kill tulips, however, if the soil becomes compacted. As grass naturally dies back, it creates a layer called thatch that is composed of decaying stems and foliage. If the thatch layer thickens past a 1-inch depth, it creates a barrier to water and compacts the soil below. Bulbs cannot access critical moisture or push their stems through the ground to gain sunlight exposure. Aerating your lawn periodically with a hollow-tine machine removes thatch and provides friable soil for vigorous grass and tulip growth.

Lawn Maintenance Consideration

• One major drawback to naturalizing tulips in lawn is turf maintenance. The tulips must be allowed to flower and die back naturally. Do not remove or mow tulip plants' spent foliage until it is completely yellow and papery to the touch. Cut your grass around the foliage until eight weeks pass after the last tulip blossom. The foliage generates and stores critical energy in the bulbs for next season's flowers. If you cannot mow around tulips effectively, it is best to plant them permanently in a flowerbed where they will not be disturbed. Also, avoid watering your lawn bulbs with sprinklers. Bulbs quickly rot in wet conditions and do not require as much moisture as actively growing grass.