Most lemon tree varieties can grow outdoors in USDA Zones 8 through 11, which means they’re hardy down to only 10 to 20 degrees Fahrenheit at the lowest. Because New Jersey is located in Zone 6, with average minimum temperatures dipping down to -10 degrees Fahrenheit, you’ll need to grow your lemon trees in containers and bring them indoors during the cold winter months. The best lemon trees to grow indoors are dwarf varieties, because their growth is easier to control and you can still enjoy fresh, homegrown lemons. Purchase a healthy lemon tree that is around 2 to 3 years old.
Prepare your planter container. Place a single layer of gravel or small stones into the bottom of a 10-gallon container that has a drainage hole. Add a peat moss-based potting mix or a sandy, all-purpose potting mix for acid-loving plants and fill the bottom one-third of the container.
Remove the lemon tree from its container carefully. Gently loosen the outer roots and place the tree into the 10-gallon planter.
Add more potting soil to the container until the soil line is just covering the top of the root ball. Ensure that the trunk is not below the soil line and firm down the soil gently with your hands.
Water your lemon tree twice per week. Mist the tree with a water spray bottle once every day when the tree is indoors, and then douse your lemon tree with a “shower” of water once or twice a month.
Place the lemon tree on your open patio or porch during late spring, summer and early autumn. You can place your lemon tree anywhere outside your house that receives full sunlight when daytime temperatures are around 70 degrees Fahrenheit and nighttime temperatures are around 55 degrees.
Move the lemon tree indoors and place it next to a southern-facing window when nighttime temperatures dip down below 40 degrees Fahrenheit. Place 40-watt fluorescent grow lights above your lemon tree in the winter to ensure that the tree receives 8 to 12 hours of light each day.
Feed your lemon tree an all-purpose citrus tree fertilizer, according to the directions on the package. Always fertilize your lemon tree during or right before watering.
Prune your lemon tree to remove any dead or dying branches and to remove suckers growing from the trunk. Thin the branches in the spring or fall to keep the fruit production healthy and avoid breakage from heavy crops.