Conifers bring tons of texture and rich shades of green to any corner. When selecting conifers to stay in large pots, do your research on which species do well in your zone. Juniper, cypress and pine varieties are some of the best conifers for pots because they have widely-available miniature and dwarf varieties. Before planting conifers in pots, check with your local nursery about the variety you plan to buy—you don't want to end up with a 10-foot-tall variety by mistake.
Plant dwarf conifers in containers with drainage holes. Use a high-quality, well-draining soil. Overwatering can drown the conifer.
Select dwarf conifers for containers rated for one USDA Zone colder than your area. For example, if you garden in Zone 5, select small conifers for pots that are hardy to Zone 4. This helps to account for the difference between planting in the ground versus planting in a pot, and gives the conifers a better chance of thriving.
Start with a pot or trough that is at least 4-5 inches larger than the pot the tree is currently living in. This gives the plant and its roots room to grow. With proper care, a slow-growing dwarf conifer can spend years in the same pot.
During the growing season, place conifer trees in pots in the type of sunlight indicated on each plant's information tag. For most dwarf conifer gardens, that means full sun. If the pot is in a place where only one side gets sun, remember to rotate every one and while to promote even growing.
In the heat of the summer or in drying winds, water the containers daily. In cool months, water the conifers regularly but less frequently (every 1–2 weeks). It's important that conifers are fully hydrated—but not soggy—when freezing weather arrives. Water plants as needed during extended winter warm spells.
Use a liquid fertilizer regularly when watering throughout the growing season, starting in late winter and ending in mid- to late summer. Liquid fertilizers are quick-releasing, so make sure to reapply as recommended by the product label. Because it starts working so quickly, liquid fertilizer is a great option for starting a conifer in a pot.
When growing conifers in pots, be sure to trim the plants to achieve the desired form. Without trimming, the plant can look a little scraggly. You can learn bonsai techniques at a local botanical garden or conservatory.
Overwinter the containers along a protected northern side of the house, out of direct sunlight and drying winds. If temperatures drop below zero, temporarily store containers in an unheated garage. Do not overwinter conifers indoors where it is heated. If animal damage is a concern, create cages of chicken wire around the plants, or place containers out of reach of rabbits and other animals.