Thanks for your response.

I live in the southeast and installed North American natives- coral honeysuckle, Virginia sweetspire, coneflower, goldenrod, blue star, Purple Dome aster, butterfly weed, and Joe Pye weed. Most were planted in the fall of 2013. Coral honeysuckle was planted in April 2014 and Joe Pye weed in September 2014. In particular, the coneflowers, coral honeysuckle, and sweetspire have struggled to produce blooms.

I do not know if the landscaper added any fertilizer or compost. The native soil here is red clay, but there's quite of bit of amended soil in the bed, so it could be considered almost a raised bed, I suppose.

I figured they just used the standard soil mix they use for trees and foundation plantings, which may be more nitrogen-rich than what is ideal for blooming plants. Not sure how to fix that. I've been using an organic bloom-booster type fertilizer this season, but I consider that just a Band-Aid solution to help the plants limp along until I can find a better solution that addresses the composition of the soil.

Thanks again for any suggestions.

Native plants seldom need fertilizer. Comment has already been made that ferts can thwart blooms.
And if they're local natives, should receive only rainfall.
Are they receiving full sun?

anren, I live in the southeast and garden in hard red clay....unamended for the most part but mulched with chips delivered by local arborists. Coneflowers are an important feature of the perennial beds and bloom their heads off.

I don't have an automated irrigation system and water very rarely with my walking sprinkler, fertigating at the same time. I haven't had to hook it up yet this year even though we're in a dry spell. Learn to love your red clay.

Thanks for your response, Jean.

Yes, the bed is in a very sunny spot on a south-facing slope and gets 6+ hours of sunlight a day.

The original idea behind this garden was to support bees and butterflies with native plants, with the added bonus of low maintenance. Since the plants grow well but don't bloom, I figure soil the landscapers used to create the bed is probably too nitrogen-rich. I'm just not sure how to correct that.

Thanks for your response, rhizo_1.

In retrospect, it was probably a mistake to have the landscapers create the bed as they did. But I'm stuck with it now. I'm hoping to find a way to correct that mistake or at least compensate for it.

Of course I am not familiar with your native plants but I know that here if you want to establish natives on previously cultivated land you often actually remove enriched soil. Natives evolved without fertilisers and irrigation and over rich soil could be inhibiting blooming as others have said.

You need to have a good reliable soil test done to see what that soils pH and major nutrient levels are, otherwise you will be just guessing. To an organic grower the soil is the most important part of the garden and what is in that soil is necessary. What to amend the soil with, if anything, cannot be determined without knowing more about the soil.

In addition to a good reliable soil test, your state universities Cooperative Extension Service probably provides that service and one does it free, these simple soil tests may also be of some use.

1) Soil test for organic
material. From that soil sample put enough of the rest to make a 4 inch level in
a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and
replace the lid, tightly. Shake the jar vigorously and then let it stand for 24
hours. Your soil will settle out according to soil particle size and weight.
For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the
bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above
that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole
1 foot square and 1 foot deep and fill that with water. After that water drains
away refill the hole with more water and time how long it takes that to drain
away. Anything less than 2 hours and your soil drains’ too quickly and needs
more organic matter to slow that drainage down. Anything over 6 hours and the
soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful
of your slightly damp soil and squeeze it tightly. When the pressure is
released the soil should hold together in that clump, but when poked with a
finger that clump should fall apart.

4) Smell. What does your
soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant
odor? The more organic matter in your soil the more active the soil bacteria
will be and the nicer your soil will smell, to a point. Too much organic matter
can be bad as well.

5) Life. How many
earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5,
according to the Natural Resources Conservation Service, indicates a soil that
is not healthy.

kimmq is kimmsr