Dead Dogwood post-mortem: How to ensure these next plants do better in clay

Question

This question is accompanied by this previous question...

Did my Dogwood die because it was planted with wire around the roots?

So clearly my two dead Dogwood trees didn't do so hot in clay. The previous landscaper recommended them and planted them but just tossed a bunch of clay on top of the root ball and sent me the bill. When I asked about why they quickly became so sickly he accused me of not watering them and refused to follow up on his guarantee to replace any dead plants in the first 2 years. I watered them for hours everyday when it didn't rain and they were pretty sickly that first year regardless. They never came back the next spring. The previous answers to my question suggested that Dogwoods just don't do well in clay so I blame my landscaper for not knowing better when he was clearly aware of the clay situation.

I dug them out as well as about 10 other dead plants and shrubs he originally planted, and I wanted to put the following plants in their place.

• Green seed rollouts of Lavender
• 2 Crepe Myrtle's
• A bunch of small flower plants that won't come back next year

Any advice to ensure the best success with these plants?

Answer 1

First, Cornus varieties do very well in heavy, clay soils, so your gardener wasn't wrong about that. Some varieties prefer neutral to acid conditions, others neutral to alkaline, and you haven't said which you were growing. Secondly, they also like rich, fertile soil, so its not clear whether your soil was enriched or emended prior to planting with humus rich materials such as well rotted animal manure. If your landscaper simply dug a hole in solid clay and planted them, it's possible the roots were sitting in water all the time because solid clay is not free draining; if you just dig a hole in it without digging the whole area first, that's where water ends up, in the hole you've made, so that might have caused a problem.

As for the plants you've now mentioned growing, Lavender hates heavy, wet soil - it likes light, free draining conditions. Crepe Myrtle grows well in most soils, except heavy, wet ones - it also likes free draining conditions.

As for 'bedding' plants, the temporary visitors, again, it depends which ones you want to grow and the actual condition/preparation of your soil. Adding as much humus rich material as humanly possible as often as possible will help with heavy clay soils, as will the addition of horticultural grit by the truck load (if you have a large garden), dug in.