It's not about order, let me explain this in terms of permutations.
With two plants, there are four possible outcomes (where M is male and F is female):
1) MM
2) MF
3) FM
4) FF
Thus, in 1/4 outcomes you get two females, in 2/4 you get one male and one female, and in 1/4 you get two males.You have a 75% chance to get at least one female plant (FF, FM, MF).
With three plants, there are 2^3 = 8 possible outcomes:
1) MMM
2) MMF
3) MFM
4) MFF
5) FMF
6) FMM
7) FFM
8 ) FFF
Thus, in only 1 of 8 permutations do you get all male plants. You chance of getting at least one female plant is 7/8, or 87.5%.
With four plants, there are 2^4 = 16 possible outcomes:
1) MMMM
2) MMMF
3) MMFM
4) MMFF
5) MFMM
6) MFMF
7) MFFM
8 ) MFFF
9) FMMM
10) FMMF
11) FMFM
12) FMFF
13) FFMM
14) FFMF
15) FFFM
16) FFFF
Thus, only in 1 of 16 possible outcomes do you end up with all male plants. Your chance is getting at least one female plant is 15/16, or 93.75%