Praise be to Allah.
Zakaat al-fitr must be given in the form of food, whatever the local staple food is, whether it be grains such as rice, lentils, beans and wheat, or fruits, such as dates and figs, if they store them and eat them as a staple food.
The staple food is whatever most of the people rely on in their diet, that can be stored, such as grains and dried fruit.
It says in al-Matla‘ (p. 175): Qoot (staple food) Is whatever food sustains people. End quote.
It says in Kashshaaf al-Qinaa‘ (6/257): Qoot (staple food) refers to bread and the grains it is made of, such as wheat, barley, corn, pearl millet and the like; the flour and saweeq made from them; dried fruits such as dates, raisins, apricots, figs and berries; meat and milk; and the like. It does not include fresh grapes, unripe grapes, vinegar and the like, such as salt and fresh dates. End quote.
Based on that, it is not permissible to give zakaat al-fitr in the form of vegetables, because they do not come under the heading of qoot (staple food).
The basic principle regarding that is:
The report narrated by al-Bukhaari (1510) and Muslim (985) from Abu Sa‘eed al-Khudri (may Allah be pleased with him) who said: At the time of the Messenger of Allah (blessings and peace of Allah be upon him), on the day of (Eid) al-Fitr we would give a saa‘ of food. Abu Sa‘eed said: Our food was barley, raisins, dried yoghurt and dates.
Ibn al-Qayyim (may Allah have mercy on him) said in I‘laam al-Muwaqqi‘een (3/12): That was the majority of the staple foods in Madinah. People in other cities or places would have different staple foods, so they must give a saa‘ of their staple foods, such as those whose staple food is corn or rice or figs, or any other grains.
But if their staple food is something other than grains, such as yoghurt, meat or fish, then they must give their zakaat al-fitr from their staple food, whatever it is. This is the view of the majority of scholars, and it is the correct view and there can be no other, because the purpose is to meet the needs of the poor on the day of Eid, and to console them and help them by giving them the same kind of food that is the staple food of the people of their land.
Based on that, it is acceptable to give flour, even though there is no sound hadith that mentions it. End quote.
Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said in ash-Sharh al-Mumti‘ (6/128): But if people's staple food is not grains or fruits – rather it is meat, for example, like those who live at the North Pole – and their staple food is mostly meat, then the correct view is that it is acceptable for them to give it [for zakaat al-fitr]. End quote.
And Allah knows best.