Does anyone have ideas to help a child that is borderline ADHD with school grades without medicine?

Sometimes. Talk with your child's doctor- they can recommend school and behavior changes that can help. Don't completely dismiss medications, though. They can be very effective. I explain that meds are like glasses- if they can't see the board, they need glasses in order to do the work. Medications are also tools to help a child focus and learn better organization and learning skills.
Besides medications. There are some non-medication approaches that can help a child with adhd. These including parent training, educational services and although they are a relatively new area of research, there are some practitioners attempting to use computerized techniques like working memory training. This last option is not yet standard of care but could be considered.
Work with school. You should request an educational evaluation to consider special assistance at school. Ask at school for an iep or 504 evaluation. Your doctor can fill a form requesting the school for special assistance for your son given his illness. This, along with a steady routine at home, should help. You will also need to help him with organizing his school and homework to help keep him in track.
BORDERLINE ADHD? Borderline adhd is like been partially pregnant.....Either you have the condition or you do not.Get a proper assessment done by someone who understands and is well trained in the subject.Medications are the primary choice in most instances, but parenting, behavioral intervention, neurofeedback, cognitive training, educational interventions as well as proper diet, sleep and exercise could all be helpful.
Lifestyle. Focus on sleep, exercise, nutrition and mind-body skills like yoga. Whole foods, organic diet rich in lean proteins, whole grains, fruits, veggies. Omega 3 fatty acids, i.e. Fish oils, specifically dha. Work w school and at home on routines and calm environment. Outdoor play! limit screen time.
Hmmm. What's "borderline adhd?" a doc needs to assess the severity & intensity of a medical condition & make therapeutic decisions based on that clinical judgment. Strict routines, good diet and sleep help any child, and should be implemented in adhd kids.
A consistent routine is essential. Get up, eat, and go to bed at the same time each day. Maintain the same schedule during the school year and summer. Be sure your child gets enough sleep. Some children see their adhd symptoms resolve with more sleep. If he still struggles, consider a medication trial-it may help both his grades and his self esteem.
Non-Medical Treatmen. This is a very good question because children who are taking medications and those who are not can still benefit from some environmental structuring in the classroom. Theses kids have trouble filtering out what is not relevant and to focus on those things that are relevant. These kids do better knowing the days schedule in the classroom, work in quieter areas of the classroom, more...
Balance. Your child's brain is two-thirds fat and neurotransmitters (serotonin, etc.) are made from amino acids, the building blocks of protein. To nourish your child's brain, be sure to include high quality fat and protein with every meal and snack.
Organized thinking. There are stories about martial arts classes helping to teach kids to focus and control hyperactivity. Music lessons have also at times shown to help with organization of thoughts. There are some occupational therapies reported to have success: interactive metronome and integrated listening systems are two brand name therapies. But don't be afraid to try medication, it sometimes helps greatly.