How do I change the soil on already planted plants (not in pots)

Question

So my plants arent growing too well in my garden (as compared to my friends with the same plants I gave them) and was wondering how do I give my plants better soil? I've already mulched the surrounding areas. Can I just dump new soil at the base of the plant? I assume no since that doesnt reach the roots. Fertilizer perhaps? New to gardening and never used that either.

Answer 1

Mulching and adding a layer of compost will improve the soil structure over time. You can speed up the process by digging them in, but take care not to damage the roots (source):

Permanent or semipermanent plantings of trees, shrubs, or perennials benefit from soil amendment too, but you need to do the job without damaging plant roots. It's often sufficient simply to spread the amendment over the soil surface as a mulch; earthworms, microorganisms, rain, and irrigation water will all carry it downward over time, gradually improving the soil's top layer. If the plant isn't a shallow-rooted type (that is, if it doesn't have many roots concentrated near soil level), you can speed up the improvement process by working the amendment into the top inch or so of soil, using a three-pronged cultivator.

Answer 2

I've never known a soil so perfect that fertilizer of basic nutrients was not indicated! Just applying DECOMPOSED organic compost to the top of the soil is truly the most effective way to improve any soil. Organisms come up to eat this stuff (if it is decomposed) and go back into the soil profile and poop it out! Mixing it in by hand is a waste of time! Besides improving the soil, it is more important to understand your soil type and your drainage!! This is why raised beds are critical to healthy plants in our gardens. If you do not have raised beds, what kind of soil do you have, what are you doing for compost, mulch, fertilizer, keeping foot traffic compaction away from your plant roots...the majority of plant roots are within 4 -6 "...I've read 94%! The rest are for support. You can make your beds raised without any boards, bricks or barrier. You keep them fluffy, airy, by not walking on them as well as adding the DECOMPOSED ORGANIC matter right on the surface. All we have to do is keep replacing this compost layer as it will disappear within a year or two. One double-digging at the very beginning to aerate is all that is necessary. Do a soil test! Dig trenches around the edges of your bed to allow accumulation of rainwater and direct it away from plant roots. Your soil is first and foremost the most important aspect of any garden. Learn what you have, improving it is simple after the fact! ALL soil can be made wonderful...just need to learn soil management...!