You could put a motion to the next general meeting to be put later in the meeting after the acceptance of the EC’s proposed budget. The motion could be along the lines of:
That the 2023-24 budget be amended by 1) the addition of $X for the refurbishment of the courtyard garden to be spend in accordance with the attached proposal and 2) an increase in the total annual levy by $X in order to leave the rest of the budget unaltered, and that future budgets include a sufficient allocation for the on-going maintenance of all common property garden areas.
The attached proposal could detail the one-off costs needed to get the garden spruced up in the first year.