According to prevalent definition of Durdhara Yoga in Vedic astrology; if in a horoscope, there is one or more than one planet in the house prior as well as the house next to the house of placement of Moon, Durdhara Yoga is formed in the horoscope. Durdhara Yoga may bless the native with good results related to profession, health, money, wealth, prosperity, authority, fame and many other things.
The placement of Sun, Rahu and/or Ketu only, in the house prior or next to the house of placement of Moon is not considered for the formation of this Yoga. Hence one or more than one planet other than Sun, Rahu and Ketu should be placed in the house prior as well as next to the house of placement of Moon in a horoscope, for the formation of this Yoga in that horoscope.
In real practice, Durdhara Yoga is not seen producing such results when only the aforementioned conditions are met. Hence more conditions should be met in order for this yoga to be formed effectively in a horoscope. If Moon is functionally benefic in one such horoscope, this yoga may produce better results. If the planet/planets placed in the prior and next house are also benefic; Durdhara Yoga may produce even better results.
Taking an example, suppose Moon is placed in the fifth house of a horoscope in Gemini, Saturn is placed in the sixth house in Cancer and Mercury is placed in the fourth house in Taurus. Moon is malefic in the horoscope whereas Saturn and Mercury are partly benefic and partly malefic. In this case, Durdhara Yoga may not be formed in the horoscope, though the primary conditions are met. The concept of a planet being partly benefic and partly malefic has been explained in the book ‘Pitra Dosh – Ancestors are Calling (Revised Edition)’.
Taking another example, suppose Moon is placed in the third house of a horoscope in Taurus, Mercury is placed in the fourth house in Gemini and Jupiter is placed in the second house in Aries. In this case, Durdhara Yoga may be formed in the horoscope; since Moon, Mercury and Jupiter are benefic. Hence the native may witness good results related to profession, reputation, finances, education, mother, family, wealth, properties and a number of other things.
Once the formation of Durdhara Yoga is confirmed in a horoscope, the next factor to check is its strength. The strength of this yoga is calculated through the placements of planets involved in its formation in various signs, nakshatras and navamshas; as well as through the influences of other benefic and malefic planets on them. The overall theme of horoscope and running times (Mahadashas) also affect the strength of this Yoga.
Taking an example, suppose benefic exalted Moon is placed in the third house of a horoscope in Taurus, in Taurus navamsha of Rohini nakshatra. Suppose benefic Mercury is placed in the fourth house in Gemini, in Gemini navamsha of Punarvasu nakshatra; and benefic Jupiter is placed in the second house in Aries, in Cancer navamsha of Ashwini nakshatra. All these planets are strong in their respective signs as well as navamshas. Hence strong Durdhara Yoga may be formed in this case.
Looking at the running times; when Mahadashas (planetary periods) of malefic planets are in effect; benefic effects of Durdhara Yoga may reduce. When Mahadashas of benefic planets other than the ones involved in the formation of this yoga are in effect; benefic effects of this yoga may increase. When Mahadashas of the planets involved in the formation of Durdhara Yoga are in effect; the native may witness maximum benefits through this yoga. For instance; in the recent example, the native may benefit the most during Moon Mahadasha, Jupiter Mahadasha and Mercury Mahadasha.