Chinese Elm (ulmus parvifolia)

Profile: The Chinese elm is well known for being a reliable bonsai species. It can tolerate a lot of mistakes and therefore makes the tree very forgiving for beginners. Chinese Elm's have vigorous lush green growth in spring and summer, and beautiful yellowing foliage in autumn. Their branches thicken quickly in late spring and summer making development faster than most other bonsai. 

Tree Position: Keep this bonsai outside in a sheltered position and protected from strong winds. It may be displayed inside for up to 3 days at a time. When placed outside, place the bonsai where it will receive full sun/part shade. During mid-summer, on very hot days, keep this tree in part shade.  

Watering: The Chinese elm loves frequent watering on hot days. Ensure that the soil is always damp but not soaking wet. How often you water your bonsai will depend on the weather and how deep your bonsai pot is. Use your finger to check how damp the soil is before watering. If it feels a little dry, then go ahead and water.  As a general rule, water every day when it's hot, and water twice a week in colder winter months. Try not to follow a schedule when watering though, instead, check the soil to see if it is wet or dry. Wait a minute or two after watering, then water again. In Japanese bonsai culture they have a saying for this; 'For bonsai, it rains two times'.

Fertilizing: Feed your Elm fortnightly from spring through to autumn with a liquid fertilizer that has a balanced N.P.K ratio. Chinese elms do benefit from a high nitrogen feed once in early spring after their leaves open fully. Always follow the directions on the fertilizer packet, and water the bonsai thoroughly before feeding to avoid root burn. Don't feed your bonsai during winter as the soil temperature isn't high enough to trigger the bonsai's response to uptake nutrients. Do not fertilize if the tree is weak or diseased. Lastly, do not fertilize newly re-potted trees for at least a few weeks.

Re-potting: Re-pot this tree every year or two during late winter or early spring just before the buds break. The soil you use should be a well-drained soil. A basic mix consists of 1 part Dalton's coarse pumice and 1 part Dalton's potting mix. Ideally, you should use a 2 mm sieve to get most of the fine particles out. You can trim up to one-third of the roots before your bonsai goes back into the bonsai pot. Secure the tree to the pot with wire through the drainage holes. Chinese elms will benefit from extra moisture in the soil (add more potting mix to achieve this). Place the bonsai in a sheltered and slightly shaded spot for a week or two after repotting. At this crucial stage, we want to shelter the bonsai from the hot sun, heavy rain, frost, snow, and wind. Lastly, be careful to not overwater your bonsai after repotting. 

Trimming: During spring and summer, your bonsai will be in full growth. Trimming is done to keep unwanted growth in check, direct growth, and to develop ramified foilage. Throughout the growing season, cut back stems to a maximum of 1 or 2 leaves. For example, if a stem has elongated too far (say it has 10 leaves), you can cut this back. Leave a minimum of 1 or 2 though. Doing this will result in dense growth. When making a cut, use sharp scissors and cut on a 45-degree angle. Aim to cut right above a leaf node. Before trimming spindly growth, think to yourself, will this stem grow into a branch that I may find useful? When your bonsai takes off in spring or mid-spring, allow the tree to grow so it can recover its strength. After a month or so of active growth, you can then trim your bonsai into shape.

Pruning: This involves cutting larger branches and requires you to have a concave or branch cutter ( if you have neither, a sharp pair of secateurs will do) The best time to make strategic pruning cuts on an Elm is from late summer through to Autumn. Don't remove more than one-third of the tree's foliage when pruning unless the Elm was vigorous in its last growing season. The overall shape you are trying to achieve is a triangular silhouette where the top of the tree is highest. Unsightly branches should also be removed. This includes dead branches, branches that cross over each other, and branches that hide the bottom third of the trunk. Create space so light and air can enter the tree.

Wiring: Wire the Elm at any time of the year. Larger branches will take longer to set than smaller branches. Elms branches (when relatively small) set in place after a very short period of time during the growing season. Ensure you are using the right thickness of wire for each branch. A general rule of thumb is that you should apply wire that is roughly 1/3 the thickness of the branch you are planning to wire. Remember to check on the wire that is applied in summer as branches thicken quickly during this time and the wire may cut into the wood and leave marks. There have been Elms that have begun to show wire marks after a week when the growth is strong and the wire is a little too tight. When wiring, try to turn any straight growth into curves (this includes the trunk and branches. Old trees tend to have twisted trunks and branches, so we copy nature here.

Pests and diseases: Elm can be affected by aphids and spider mites. Spray these with a diluted solution of dish soap and water. Repeat after 7 days to kill any eggs that may have hatched. Yellowing leaves can signify the beginning of root rot or nutrient deficiency. Check the soil first and then look at correcting the deficiency by researching the discoloration or mutation of the leaf. It should be noted that Elms will often have a few yellow leaves during the growing season in response to dealing with excess nutrients. Elms are also deciduous trees which means that they lose their leaves every year in a fantastic show. 

Bonsai Difficulty: ★☆☆☆☆