Multiple ACF Repeaters within a Custom Post Type

You’ve mixed a few things up in your template

The opening repeater field for example you have called garden_tips after the name of the ACF Field Group instead of the name of the repeater

Eg:

therefore you need to remove that and the closing <?php endif; ?> which related to it further down the template.

Then look at each section eg: Flowers and do something like this

<?php if( have_rows('flowers') ): ?>
 <h6>Flowers</h6>
 <ul class="garden_tips_list">
  <?php while( have_rows('flowers') ): the_row(); ?>
  <li>
   <i class="fas fa-leaf"></i> <?php the_sub_field('flower_tip'); ?>
  </li>
  <?php endwhile; ?>
 </ul>
<?php endif; ?>

You’ll need to do this for each section.

With the banner, this isn’t inside a repeater and you’re using get_sub_field instead of get_field.

You should also make sure you return the image Object, rather than the ID or URL (its in the settings of the field) then
use something like this for getting the image url itself

$banner = get_field( 'banner_image' ) ? : false;
if( $banner ):
    $bannerSize="medium_large";
    $bannerUrl = $banner['sizes'][$bannerSize];
    $bannerAlt = $banner['title'];?>
<img src="<?php echo $bannerUrl;?>" alt="<?php echo $bannerAlt;?>">
<?php endif;?>

Overall, it should be something like this

    <?php get_template_part('header'); ?>
        
        <?php get_template_part('includes/inner-post-header'); ?>
        
        <section class="e-blog-v3 garden-set-pd-sm-lg">
          
          <div class="container">
            
            <div class="row">
              
              <div class="col-sm-12">
                
                <?php while ( have_posts() ) : the_post(); ?>
        
                  $banner = get_field( 'banner_image' ) ? : false;
        if( $banner ):
            $bannerSize="medium_large";
            $bannerUrl = $banner['sizes'][$bannerSize];
            $bannerAlt = $banner['title'];?>
<img src="<?php echo $bannerUrl;?>" alt="<?php echo $bannerAlt;?>">
<?php endif;?>
    
    
                  
                  <?php if( have_rows('flowers') ): ?>
                  <h6>Flowers</h6>
                  <ul class="garden_tips_list">
                  <?php while( have_rows('flowers') ): the_row(); ?>
                    <li>
                      <i class="fas fa-leaf"></i> <?php the_sub_field('flower_tip'); ?>
                    </li>
                  <?php endwhile; ?>
                  </ul>
                  <?php endif; ?>
        
                  
                  <?php if( have_rows('fruit_veg') ): ?>
                  <h6>Fruit and Veg</h6>
                  <ul class="garden_tips_list">
                  <?php while( have_rows('fruit_veg') ): the_row(); ?>
                    <li>
                      <i class="fas fa-leaf"></i> <?php the_sub_field('fruit_veg_tip'); ?>
                    </li>
                  <?php endwhile; ?>
                  </ul>
                  <?php endif; ?>
        
        
                  <?php if( have_rows('greenhouse') ): ?>
                  <h6>Greenhouse</h6>
                  <ul class="garden_tips_list">
                    <?php while( have_rows('greenhouse') ): the_row(); ?>
                    <li>
                      <i class="fas fa-leaf"></i> <?php the_sub_field('fruit_veg_tip'); ?>
                    </li>
                    <?php endwhile; ?>
                  </ul>
                  <?php endif; ?>
        
                            
                  <?php if( have_rows('garden_maintenance') ): ?>
                  <h6>Garden Maintenance</h6>
                  <ul class="garden_tips_list">
                    <?php while( have_rows('garden_maintenance') ): the_row(); ?>
                    <li>
                      <i class="fas fa-leaf"></i> <?php the_sub_field('fruit_veg_tip'); ?>
                    </li>
                    <?php endwhile; ?>
                  </ul>
                  <?php endif; ?>
        
        
                <?php endwhile; // end of the loop. ?>
        
            </div>
          </div>
        </section>
        
        <?php get_template_part('footer'); ?>