Firstly, yes all lavender is perennial. But that doesn't mean it will survive winter in any climate, it just means it is perennial in its native habitat.

Spanish Lavender is more tender than English. It doesn't even survive a winter over here in the UK. If you can remember the flowers you should be able to tell if you had English or Spanish. The latter has 'bunny ears'.

You don't say if your lavender was in a pot or in the ground. If in a pot it would be more susceptible to cold so you'd probably do best to have it in the ground. Lavender needs good drainage whether in the ground or in a pot.

Yes do try again with English Lavender. Give it full sun and excellent drainage. I have grown it in the ground for decades. Do not cover it for winter or cut it back. I wait until new growth starts and just run my hand through it to crumble the old leaves. Then I wait a couple of weeks and lightly clip back any dead tips to the new growth.

Given that I'm zone 6 in Maine and I've been to High Point, NJ, which wasn't very high, I suspect your zone has been upzoned. I used to be Z5. Have you checked recently?

The classic lavender is usually English lavender. But you can google the difference. I've had no trouble overwintering mine in Maine. Plants can have small genetic differences. Plants that have been propagated from southern stock may be less cold tolerant than those propagated from Northern stock. Many plants in Maine nurseries have tags saying "Northern grown". Equally, if you live near a warmer zone, Home Depot might be selling plants that are only good to that warmer zone or otherwise might be marginal in your zone.

All that said, Lavender likes good drainage and soil that stays damp in the winter is bad for it. Knowing nothing but what you've told me, that would be my guess.

There was a recent thread that discussed cold hardiness of lavenders, including someone in Canada , I think. I can’t remember the title or how it started, so you would just search.

marmiegard_z7b I do believe that would have been me. I also posted here 2 comments above.

Thanks everyone for the feedback. Can you provide more details on what the soil should be like? How big of a hole should I dig? Replace the dirt with loam, or perhaps a combination of top soil and sand or potting soil and sand?

@gosssamer

I have 6 Sentivia English LavenderI just planted it is hardy to -10 to -20 zone 4b. I will link to a description of soil but basically drought resistant 14”x 20” size very early flowering likes alkaline soil. .

I also got 3 Javelin Forte Monrovia that are almost identical to a Spanish Lavender. i planted it on a slope where my Spanish was thinning out after 5 winters here in 7b. Its hardy to 10F-20F .

https://plants.englishgardens.com/12150001/Plant/31624/Sentivia_Early_Blue_Lavender

https://www.monrovia.com/javelin-forte-deep-purple-spanish-lavender.html?srsltid=AfmBOoqjsjRvR__-iqg8yuprZwmopa07J-z3QNeQFJ196X4CZ48PWBYU

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