citrus questions

Hello,
I bought a mandarin orange plant and a grapefruit plant in the summer. Unfortunately when I went away, they were either over watered or under watered, because when I came back, they dropped their leaves. After a little dormant period, they have started to shoot again. I looked closer today and see that they are shooting from the bottom of the "trunk".
Now I should explain that I am new to all this (if that wasn't obvious already). Three quarters of the way up the trunk there is a faint diagonal line, so I am wondering if this is the graft? I have read some books and they say when repotting citrus, to make sure the graft is above soil level. Reading that made me think the graft was quite low, so I'm not sure; these are a foot high. Does the graft rise as the plant grows?
I know apples for example are grafted. I hadn't realised citrus was. The thing is, these new shoots are below, what I think may be the graft. Without waiting months for them to flower and fruit, do you think that what I am growing is not what I am expecting? What are citrus grafted onto (and why?).
Is this the best place to ask citrus questions? I visited yahoo groups but that found 120 groups matching "citrus" though most seemed to have nothing to do with fruit! The ones that did had only 5-7 members!
Thanks for your help.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Almost all citrus sold in here in S. Florida are grafted onto "sour orange" root stock for hardiness and pest control. The graft may rise slightly as the tree grows and yes you shouldn't bury it. It sounds like someone overwatered your plants and may have killed the grafted tree. You are getting suckers from the root stock that will not produce a fruit that you will want to eat.
All of this having been said... your best bet for citrus in the long run is a supermarket. From your e-mail address I will assume you are in the UK where citrus grown outdoors has to be an impossible task at best. Citrus trees need positive drainage, minimal water, and good quality citrus oriented fertilizer. Sure you can grow them indoors if you've got the room and the time. But citrus trees grown in the ground will eventually produce far more fruit than you, your family, your neighbors, and your friends can eat!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.