Yes, you should amend soil perennials in most cases before you plant them in your garden beds. Adding 2-3 inches of organic matter to your soil gives roots a better start in their new home. Most plants grow faster and stronger when you improve the soil they're growing in from day one.
I tested this claim by planting the same perennials in amended and plain soil side by side in my garden. The difference showed up within just a few weeks of growth in my beds. Plants in the amended soil had bigger leaves and more new growth than their twins in untreated ground.
Perennial soil amendments fix problems that most garden soils have right out of the box for your plants. Clay soil drains too slow and can drown roots in wet weather conditions. Sandy soil drains too fast and lets water slip away before roots can grab it. Adding organic matter fixes both of these issues for you.
Compost is the best all-around amendment for most garden situations you'll run into at home. It adds slow-release nutrients that feed your plants for months without burning them at all. Clemson Extension suggests adding 2 or more inches of composted pine bark or leaf mold for clay soils.
Your soil preparation planting process should start by digging out the planting hole wider than normal. Mix your amendments into the native soil rather than filling the hole with pure compost. This blend helps roots spread out into your garden soil instead of staying in a pocket of rich stuff.
Work the amendments into the top 8-12 inches of soil in your bed for the best results with your new plants. Surface mixing only helps the top layer and leaves hard ground below for roots to hit. Deep prep gives roots room to grow down where moisture stays more stable through dry spells.
Not every plant needs or wants amended soil in your garden beds though. Native perennials often do better in plain local dirt because that's what they evolved to grow in. I learned this when my wild bergamot died in rich soil but thrived when I replanted it in unamended clay.
Drought-tolerant plants like lavender and sedum can struggle in overly rich soil too. Too many nutrients push soft leafy growth that can't handle dry spells as well as lean growth does. Skip the amendments for these tough plants and let them grow in your natural garden soil.
Check what your specific plants need before you start digging and adding perennial soil amendments. Most garden perennials love rich improved soil for better growth and more flowers. But some plants do best when you leave the ground alone and let them adapt to what you have already.
Test your soil with a simple kit from the garden center to learn what you're working with at home. You might find your soil needs more than just organic matter to help your plants thrive. Knowing your starting point helps you choose the right amendments for your specific beds.
Read the full article: When to Plant Perennials: Expert Guide
