Should I add fertilizer to a new potted lemon tree?
In container, you will want to fertilize these every few months. Container citrus tend to wash out faster then in ground. You can go ahead and add a fertilizer for now if you would like. It is also good to have dolomitic lime and iron sulfate around, as this will prevent many things that will happen to a container citrus in the future.
What should you do if the tree is returning some green leaves at the base, but it is dead looking on top? should the brown limbs be trimmed?
Not until warm weather returns. You should cut off the bottom growth, though. These are likely below a graft point, and not the same tree. These will quickly outgrow the main tree.
Just trim the dead growth after you see signs of new growth on the top portion of the plant.
Hi, I started lemon tree from organic lemon seed, have it growing since December 2016, looks fine but it is very tiny is it normal, when will it form as a tree? do I need to do something, it is indoor, in the pot about 5 inches
For being only 4 months old, that lemon tree looks great! It will take quite a few years for it to reach "tree" size, and even longer for it to produce fruit. But in the meantime, you will see it get bigger and bigger. Make sure it gets at least 4-6 hours of sunlight per day. When it gets a little bigger, you'll want to repot it an move it away from that smaller seedling.
You can read more about growing lemons from seed here:
https://www.gardeningknowhow.com/edible/fruits/lemons/propagating-lemon-seeds.htm
Is it a good idea to place a liver in the planting hole to promote growth and fruit
The only meat that should be used in this fashion is fish. Other meats will tend to draw pests, and infections in the soil. I would not advise this.
I had a lemon tree and it died and I cut it down. Left a stump from the trunk with green sprout growing from it. I have watered it until it is about 5' tall and real bushy and green. Will it ever produce lemons?
It has likely grown from the grafted stock on the citrus. There is no way to know the type of citrus stock used, an it could likely be a lemon stock that may not be very flavorful.
There is no way to know until is does produce if it is an edible fruit.
Do you suggest we prune this seed-grown, indoor lemon tree? It's about three years old, never been outside (we are on the 12th floor of a downtown office building). Not sure why the leaves are getting yellow/rust colored on a few lower branches. Any advice is appreciated.
The yellowing leaves are likely a watering issue; too much or too little. It's important to evenly water a Citrus. Soil should be moist, never dry and never soggy.
Your Lemon Tree is very tall, and you need to prune the tree for the health of the tree or it simply will become too tall.
Lemon Tree need full sun location.
Pruning can take place in early spring, so now would be a good time.
I've listed several links to help you.
https://www.gardeningknowhow.com/edible/fruits/lemons/how-to-grow-a-lemon-tree.htm
https://www.gardeningknowhow.com/edible/fruits/lemons/lemon-tree-pruning.htm
http://www.wikihow.com/Prune-a-Lemon-Tree
https://www.gardeningknowhow.com/edible/fruits/lemons/learn-about-fertilizer-for-a-lemon-tree.htm
I have a 3ft lemon tree in a pot. I brought it in last fall. It had many blooms come on. I notice a scaly bumps on the leaves and where the branches meet. I continuely wipe these off with alcohol on cotton balls. It just get more. It some type of parasite
Yes, it is the scale bug. They will, completely, destroy the tree if left untreated. You should scrape off as many as you can, then spray the tree with neem oil. This will keep them from coming back. Unfortunately, they seal themselves to the tree, so unless you, manually, remove them, then the neem oil will not affect them.
This article will give you more information: https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm