Virtues of the Month of Rajab
Question

The early generations (Salaf) said that the month of Rajab is the month of planting the seeds. My question is: what seeds should the Muslim plant?
Praise be to Allah.Virtues of the month of Rajab
The month of Rajab is one of the sacred months concerning which Allah, may He be Exalted, says (interpretation of the meaning):
{Indeed, the number of months with Allah is twelve [lunar] months in the register of Allah [from] the day He created the heavens and the earth; of these, four are sacred. That is the correct religion, so do not wrong yourselves during them. And fight against the disbelievers collectively as they fight against you collectively. And know that Allah is with the righteous [who fear Him]} [At-Tawbah 9:36]
The sacred months are: Rajab , Dhul-Qa`dah, Dhul-Hijjah and Muharram.
Al-Bukhari (4662) and Muslim (1679) narrated from Abu Bakrah (may Allah be pleased with him), that the Prophet (blessings and peace of Allah be upon him) said: “Time has returned to its original order as it was on the day when Allah created the heavens and the earth. The year is twelve months, of which four are sacred: three consecutive months, Dhul-Qa`dah, Dhul-Hijjah and Muharram, and Rajab of Mudar, which comes between Jumada and Sha`ban.”.
These months are called sacred for two reasons:

Because of the prohibition on fighting during them, unless the enemy starts it.
Because transgressing the sacred limits during them is more grievous than at other times.

Hence Allah, may He be Exalted, forbade us to commit sin during these months, as He says (interpretation of the meaning): {so do not wrong yourselves during them.} [At-Tawbah 9:36] Although committing sin is forbidden and prohibited during these months and others, in these months it is more emphatically prohibited.
As-Sa`di (may Allah have mercy on him) said in his Tafsir:
“{So do not wrong yourselves during them} It may be that the pronoun (them) refers to the twelve months, and Allah the Almighty stated that He has made them a means of measuring time, so time should be filled with acts of obedience and thanks should be given to Allah for this blessing and His making the months a means of serving people’s interests, so let them beware of wronging themselves during these (twelve) months;
Or it may be that the pronoun refers to the four sacred months, and that this is a prohibition on wronging themselves during them, especially when this prohibition applies at all times, because these months are extra special and wrongdoing at that time is more serious than at other times.”
The month of Rajab marks the beginning of preparations for Ramadan
The scholars likened the year, and what it contains of special seasons and occasions to several things. The greatest of its special seasons is the month of Ramadan, hence Islam urges us to do more righteous deeds during that month.
One of the most important things is to prepare for doing righteous deeds before the month of Ramadan. The scholars designated the month of Rajab as the start of the preparations for the month of Ramadan . It is as if the year is a tree; its leaves begin to appear in the month of Rajab, its fruit begins to appear in the month of Sha`ban, and the people pick its fruit during the month of Ramadan.
So the individual should prepare himself by doing righteous deeds in Rajab, and pay extra attention to making them perfect in Sha`ban, so that he will be able to do them in a perfect manner in Ramadan.
The scholars refer to this idea in several ways, including the following:

It was said that Rajab is for a person to stop drifting away, Sha`ban is for striving and sincerity, and Ramadan is for truthfulness and purity.
Rajab is the month of repentance, Sha`ban is the month of love, and Ramadan is the month of closeness to Allah.
Rajab is the month of sanctity, Sha`ban is the month of service, and Ramadan is the month of blessing.
Rajab is the month of worship, Sha`ban is the month of turning away from this world, and Ramadan is the month of increase.
Rajab is the month in which Allah multiplies the reward of good deeds , Sha`ban is the month of expiating bad deeds, and Ramadan is the month of waiting for gifts and honours.
Rajab is the month of those who are excelling, Sha`ban is the month of those whose progress is moderate, and Ramadan is the month of the sinners [in which they can mend their ways].

Dhun Nun Al-Masri (may Allah have mercy on him) said: “Rajab is the month for giving up sins, Sha`ban is the month for doing acts of obedience, and Ramadan is the month for waiting for gifts and honours. So whoever does not give up sins, and does not do acts of obedience, and does not wait for gifts and honours, is one of the people whose main focus is trivial matters.
He (may Allah have mercy on him) also said: Rajab is the month of planting, Sha`ban is the month of irrigating, and Ramadan is the month of harvesting. Everyone will reap what he sowed, and will be requited for what he did, so the one who neglects his crops will feel regret on the day of harvest, and he will not get what he was expecting.
One of the righteous said: The year is a tree, Rajab is the time when its leaves appear, Sha`ban is the time when its fruit appears, and Ramadan is the time when the fruit is picked.” (Al-Ghaniyyah by Al-Jilani, 1/326)
Ibn Rajab (may Allah have mercy on him) said in Lata’if Al-Ma`arif (121): “The month of Rajab is the key to the months of goodness and blessing.
Abu Bakr Al-Warraaq Al-Balkhi (may Allah have mercy on him) said: The month of Rajab is a month for sowing, the month of Sha`ban is a month for irrigating the crop, and Ramadan is a month for harvesting the crop.
And it was narrated that he said: The likeness of the month of Rajab is that of the wind, the likeness of Sha`ban is that of a cloud, and the likeness of Ramadan is that of the rain.
One of them said: The year is like a tree; the month of Rajab is the time when its leaves appear, Sha`ban is the time when its fruits appear, and Ramadan is the time when its fruits are picked; the believers are the ones who pick the fruit.
It is appropriate for the one whose page has been darkened with sin to brighten it by repenting during this month, and for the one who has wasted his life in idleness to make the most of what remains of his life.
So brighten your dark page in Rajab with righteous deeds that will save you from the flames.
One of the sacred months has come, so the one who calls upon Allah will not be disappointed.
Glad tidings to the one who does a sincere righteous deed in this month, and gives up obscenity and dubious matters during it.
Making the most of this opportunity by striving during this month is gain, and making the most of its time by doing acts of worship and obedience is immense virtue.”
So the individual should sow a lot of good seeds and do a lot of righteous deeds . These are the seeds that he should plant during his lifetime, hoping for the day of harvest when he meets the Lord of the Worlds with a crop of good deeds.
Among the most important things that a person may do in Ramadan are:

Prayer, both obligatory and supererogatory (Nafil) prayers, especially Qiyam Al-layl (voluntary prayers at night).
Fasting .
Charity.
Reading Quran.
Dhikr.

Adh-Dhahabi (may Allah have mercy on him) said: “By Allah, reciting one seventh of the Quran in Tahajjud as Qiyam Al-layl, along with consistently offering the regular Sunnah prayers, praying Duha and the prayer to “greet the mosque” (Tahiyyat Al-masjid); as well as reciting the soundly narrated Adhkar, the Du`a’s for going to sleep and waking up, the Adhkar to be recited following the obligatory prayers and in the time before dawn; studying beneficial knowledge and focusing on it sincerely for the sake of Allah; enjoining what is right, guiding and teaching one who is ignorant, rebuking one who is an evildoer, and so on; offering the obligatory prayers in congregation with focus, tranquillity, humility and faith; doing all obligatory duties and avoiding major sins; offering a great deal of supplication and prayers for forgiveness; giving charity and upholding ties of kinship; and showing humility and sincerity in all of that is an immense task, and it is the way of those on the right, the pious close friends of Allah.” (Siyar A`lam An-Nubala’,  3/84)
And Allah knows best.