Here's a great tool that will do all the hard work for you. 

The Spiral Hole Drill Planting & Grass Plug Auger is a handy gardening tool for planting bulbs, bedding plants, and seedlings. Designed to help you plant your grass plugs and small annuals much faster than using a shovel or garden trowel, this drill bit actually pulverizes the soil, giving your plants better soil-to-root contact.

It makes gardening maintenance quick and easy even for novices!

Practical Tool: This handy gardening tool dig holes with ease and makes gardening maintenance quick and easy. Perfect bulb planting auger for tulips, iris, bulbs, bedding plants, and seedlings. 

Quality Material: Made of high-strength steel material, designed and developed to bulldoze through the rockiest soils for easier and quicker planting of bulbs or weed removal.  

Energy Saving: Use any electric or cordless drill that can accommodate a 3/8" bit. Not only does it dig deep holes, it instantly pulverizes the soil, making it convenient for you to plant more in less time.