It's not the cold here that gets Lavender, it's our humid summers and our wet wet winters. That is the reason for the hole. While it won't really cost you 200, you might begin to feel like it. Since our bluff soil is mostly clay, Lavender can not survive being simply stuck in our ground. (see gardening tips for July 98). So you need to work your beds down about 18 inches at the least and 24 for good measure. It is best to raise the bed by about 6 inches. Bring the bed to 1/3 sand, 1/3 loam and 1/3 clay. Erring with too much sand is better than too much clay. You must get the sand level up. Just plain builder's sand from the local hardware store is great. 

Okay, now you got a hole worth planting Lavender into. Get yourself a good healthy plant. Lavender Munstead, Hidcote or English is best for our area. Spanish and French can not make it past our winters. Lavender does not like transplanting much so you will do better with a purchased plant from a good nursery. Now that you have your hole that you have worked so hard on, be careful not to go to a discount store and get a discount plant. Besides Lavender Earth, there are many greenhouses in town that carry great plants. (we like us best and you will have me to tell you more if you come here:-)) 

Place white marble rock chips around the bottom of your plant to reflect the sun and help to dry some of the moisture due to our humidity and marble will help with a bit of alkaline substance. 

Okay now watch it grow. You can do the watering you need to because you no longer have to worry about rotting your roots and you don't have to worry about the winter rain. But remember that Lavender enjoys too little watering versus too much. Hope you enjoy this wonderful plant.