Edit in JSFiddle

<div class="form-group">
    <label for="exampleInputName">Name</label>
    <input type="text" class="form-control" id="exampleInputName" placeholder="名前を入力してください">
</div>

<div class="form-group">
    <label for="exampleMemo">Memo</label>
    <textarea class="form-control" rows="3" id="exampleMemo" placeholder="1000文字まで入力できます"></textarea>
</div>

/* Chrome, Safari */
.form-control::-webkit-input-placeholder{
    color: #ff9900;
}

/* Firefox */
.form-control::-moz-placeholder{
    color: #ff9900;
}

/* Firefox 18以前 */
.form-control:-moz-placeholder{
    color: #ff9900;
}

/* IE */
.form-control:-ms-input-placeholder{
    color: #ff9900;
}