To prepare lavender for winter you need to prune in late summer, add mulch once the ground freezes, and cover plants in cold zones. These three key steps give your lavender the best shot at making it through to spring alive. Skip any of them and you risk losing plants to the cold weather.
I lost half my lavender collection during my first winter growing them in zone 5. The uncovered plants turned brown and never came back in spring. The ones I wrapped with burlap survived just fine. That hard lesson taught me to take winterizing lavender plants more serious.
Missouri Extension research backs up what I saw in my own yard. Covered plants survived winter in their studies. Uncovered ones died or had severe damage from cold and wind. Even a simple burlap wrap makes a huge difference when cold winds blow through your garden beds.
Start your prep by pruning plants in late summer around August for most areas. This gives stems time to harden off before frost hits. Don't prune too late in fall since new growth won't have time to toughen up. Fresh tender shoots die fast when temps drop below freezing.
Wait until your ground freezes before you add mulch around the base of your plants. A 2-3 inch layer of straw or shredded leaves works great to insulate roots. Mulching too early traps heat and confuses plants into staying active when they should go dormant instead.
Your lavender winter care needs will depend on where you live in the country. Plants in zones 7-10 need little to no extra help through winter months. Zones 5-6 benefit from mulch and fabric covers on the coldest nights. Zone 4 and colder areas may need to grow lavender in pots that move inside.
Check on your covered plants a few times during winter when temps rise above freezing for a day or two. Too much moisture under covers can cause rot problems just as bad as cold damage. Lift covers on mild days to let air flow through and dry things out a bit.
Remove covers and mulch gradually as spring arrives in your area later in the year. Don't rush this step or you'll shock plants with sudden temp swings. Take off a little each week as days warm up. Your lavender will push out fresh new growth once it feels safe from frost danger.
Read the full article: How to Grow Lavender From Seed Successfully
