How to minimise student's discomfort when suggesting they need to improve his/her English? The standard of English grammar, spelling and syntax is abysmal in my country. High school students generally learn such things by studying a foreign language. 

As a result, the written work I receive from students whose native tongue is English frequently has many errors - including the usual:


Typographical errors
Apostrophes in the wrong place (its, it's)
The following fails: their/there/they're; whose/who's
And, generally, failing to check spelling, grammar and to proof read thoroughly.


The typos and failure to proof read thoroughly I can understand and treat accordingly, namely encourage students to proof read and check their work carefully, or get a friend/colleague/family member to help.

The failures in English grammar, syntax and punctuation - which I suspect arise from a deficient treatment at school - I find hard to forgive.

Our University has extensive support for improving the English for both native and non-native English speakers. 

I feel concerned, however, about suggesting to those students who are native English speakers, but who need more training, to attend the help workshops available to them. This is for fear of embarrassing or alienating the students. Is there a sensitive way of dealing with this? Should I even try to spare the students' blushes?
One way to approach this is from the perspective of why the quality of prose matters in the first place.  After all, why should we bother with spelling, grammar, etc?
Having good spelling, grammar, etc. is important because not having them puts roadblocks in the way of communicating with the reader.

You can minimize a student's embarrassment by emphasizing this aspect.  Assuming that student is otherwise doing well, you might can bring up grammar by approaching it from this angle.  You can emphasize the pragmatic aspect that, in pretty much any career they choose, written communication will be important, and that it's important to not have others' appreciation of their good work be impeded by problems with grammar and spelling.  It's really the linguistic equivalent of keeping yourself clean and well-groomed.

If a student is not doing well with the core material... well, then grammar's not really the key problem to talk to them about anyway...