<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-04-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000100893</issuerCik>
        <issuerName>UNION PLANTERS CORP</issuerName>
        <issuerTradingSymbol>UPC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001181803</rptOwnerCik>
            <rptOwnerName>HENRIQUES ADOLFO</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P. O. BOX 387</rptOwnerStreet1>
            <rptOwnerStreet2>ATTN: LEGAL DIVISION</rptOwnerStreet2>
            <rptOwnerCity>MEMPHIS</rptOwnerCity>
            <rptOwnerState>TN</rptOwnerState>
            <rptOwnerZipCode>38147-</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO,Union Planters Bank, FL</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>80887</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-04-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>28</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>671</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By ESOP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>675</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>338</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By wife and son</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-04-21</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>295</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>524</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(K)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Phantom Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F4"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>27872</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27872</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Emp.Stock Option(right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>24.81</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-10-08</value>
            </exerciseDate>
            <expirationDate>
                <value>2012-10-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>125000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>125000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Emp.Stock Option(right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>25.5867</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-10-10</value>
            </exerciseDate>
            <expirationDate>
                <value>2011-10-10</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>112500</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>112500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Emp.Stock Option(right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>26.1667</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2009-12-16</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>45000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>45000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Emp.Stock Option(right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>31.2917</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2001-10-14</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-10-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>13350</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>13350</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Emp.Stock Option(right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>33.48</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2004-10-14</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-10-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>93750</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>93750</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qual. Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>22.92</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-12-20</value>
            </exerciseDate>
            <expirationDate>
                <value>2010-12-20</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>63000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>63000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Reporting person acquired 28 shares of common stock under the ESOP Plan.  The information is this report is based on a plan statement dated as of April 21, 2004.</footnote>
        <footnote id="F2">Reporting person acquired 295 shares of common stock under the 401(K) Plan.  the information in this report is based on a plan statement as of April 21, 2004.</footnote>
        <footnote id="F3">Phantom stock accrued under UPC Deferred Comp. Plan for Executives during 2000 at prices ranging from $28.58 to $34.48.                                         The units are to be settled in cash upon the reporting person's termination of employment.</footnote>
        <footnote id="F4">Phantom stock units accrued under UPC Deferred Comp.Plan for Executives at various dates during 2000 at prices ranging from $28.58 to $34.48.                   Stock to be settled in cash upon the reporting person's termination of employment.</footnote>
        <footnote id="F5">The option vests in three equal installments beginning on 12/16/00.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>E. James House, Jr./Rebecca Baggett</signatureName>
        <signatureDate>2004-04-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0201
4
2004-04-21
0
0000100893
UNION PLANTERS CORP
UPC
0001181803
HENRIQUES ADOLFO
P. O. BOX 387
ATTN: LEGAL DIVISION
MEMPHIS
TN
38147-
0
1
0
0
CEO,Union Planters Bank, FL
Common Stock
80887
D
Common Stock
2004-04-21
4
J
0
28
0
A
671
I
By ESOP
Common Stock
675
I
By trust
Common Stock
338
I
By wife and son
Common Stock
2004-04-21
4
J
0
295
0
A
524
I
By 401(K)
Phantom Stock
0
Common Stock
27872
27872
D
Emp.Stock Option(right to buy)
24.81
2004-10-08
2012-10-08
Common Stock
125000
125000
D
Emp.Stock Option(right to buy)
25.5867
2004-10-10
2011-10-10
Common Stock
112500
112500
D
Emp.Stock Option(right to buy)
26.1667
2009-12-16
Common Stock
45000
45000
D
Emp.Stock Option(right to buy)
31.2917
2001-10-14
2008-10-14
Common Stock
13350
13350
D
Emp.Stock Option(right to buy)
33.48
2004-10-14
2013-10-14
Common Stock
93750
93750
D
Non-Qual. Stock Option
22.92
2003-12-20
2010-12-20
Common Stock
63000
63000
D
Reporting person acquired 28 shares of common stock under the ESOP Plan.  The information is this report is based on a plan statement dated as of April 21, 2004.
Reporting person acquired 295 shares of common stock under the 401(K) Plan.  the information in this report is based on a plan statement as of April 21, 2004.
Phantom stock accrued under UPC Deferred Comp. Plan for Executives during 2000 at prices ranging from $28.58 to $34.48.                                         The units are to be settled in cash upon the reporting person's termination of employment.
Phantom stock units accrued under UPC Deferred Comp.Plan for Executives at various dates during 2000 at prices ranging from $28.58 to $34.48.                   Stock to be settled in cash upon the reporting person's termination of employment.
The option vests in three equal installments beginning on 12/16/00.
E. James House, Jr./Rebecca Baggett
2004-04-22