The lemons are bright yellow when mature, have juicy, acidic flesh, and contain few seeds or none at all. Lisbon lemons are often confused with another popular lemon variety—Eureka. Lisbon lemon trees can be planted throughout the year in warm climates and generally reach maturity within three years. If you plan to overwinter them indoors, plant them in the spring after any danger of frost has passed. They can reach up to and over 15 feet when grown outdoors but are more dwarf-like when kept in containers. They also produce pretty white blooms that have a fragrance reminiscent of orange blossom. The skins and plant materials of the lemon are toxic to cats, dogs, and horses. Lemon trees need to be planted in a site with good drainage. If you are concerned, you could plant your tree on top of a wide mound of soil or select a sloped position for better drainage. The hole should be three to four times the diameter and three times as deep as the lemon tree container. The large hole loosens the surrounding soil allowing the lemon tree roots to grow freely. It is not necessary to apply fertilizer, topsoil, or compost to the hole. Backfill the hole with some of the soil and place the tree in the hole so that the top of the root ball is level with or slightly above the surrounding soil level. Fill soil in around the tree roots and tamp slightly to remove air pockets. Immediately water the soil around the tree and tree roots. These trees grow well in containers and can be moved inside if frost is expected during the winter. Make sure the pot is large enough, has good draining, and that you select a potting mix suited to citrus trees.
Lisbon Lemon Tree Care
Light
If you don’t have a garden that receives plenty of sunlight, then the Lisbon lemon tree won’t be for you. This species needs a full sun position to thrive.
Soil
Lisbon lemon trees can handle a variety of soil types but have a preference for those on the acidic side, and good drainage is an absolute must. Soggy roots are a problem for all lemon trees, and pooling water around the trunk should be prevented.
Water
Getting the watering balance right for your Lisbon lemon tree can make a big difference in terms of their vigor and fruit production levels. While the tree is getting established, it’ll need more watering during the first few years. As it matures, it becomes more drought tolerant. Young trees especially prefer the soil to remain moist during the summer. Slow and deep watering every fortnight is usually recommended, but it’ll need to be done more often in very hot or dry soils. Excessive watering, however, can lead to root rot. Be careful not to overdo it!
Temperature and Humidity
Although Lisbon lemon trees are slightly more cold-tolerant than their Eureka relatives, it’s important to remember that lemons are the most sensitive to cold weather of all the citrus fruits. This is particularly true of young trees that aren’t so well established. If you plan to keep them outdoors, you need to have guaranteed mild winters. If temperatures go below 30 degrees Fahrenheit, your tree may not survive outside. Their preference is for temperatures to be around 75 to 85 degrees Fahrenheit to produce the best harvest.
Fertilizer
Since Lisbon lemon trees produce such an abundance of fruit, they use up a lot of energy. Unless your tree is planted in particularly fertile soil, they’ll appreciate a bi-annual feed of a fertilizer specifically designed for citrus fruits. If they don’t receive enough nutrients, your crop will be diminished, the growth of the tree can be stunted, and the leaves can become discolored.
Lisbon Lemons vs. Eureka Lemons
The Lisbon lemon rind has a smoother texture and a more prominent mammilla (protruding nipple). Lisbon lemon trees are thornier than Eurekas, more tolerant of the cold, and produce more fruit. Unlike Eureka, whose lemons are found on the outside of the tree, Lisbon lemons are located inside the dense, glossy, green canopy. The tree has a more upright and spreading growth habit, too.
Harvesting Lisbon Lemons
Don’t expect a newly planted tree to produce a bumper crop instantly. It can take a few years before you’ll start seeing lemons in the canopy. If you do spot any random flowering in advance of this, it can be a good idea to remove them to allow all the energy to be conserved to support appropriate early growth. When the conditions are right, this type of lemon tree is known for producing a good crop throughout the year. However, the biggest harvest is usually in the winter or early spring. As with all citrus fruit varieties, the Lisbon lemon won’t ripen off the tree. It should remain there until soft to the touch, fully ripened, and ready to use.
Pruning
Lisbon lemon trees have an upright, spreading habit, and regular pruning will help to keep their shape, produce a strong canopy, and encourage healthy and abundant fruit production. Pruning is best done after harvesting, and it should involve a technique referred to as “skirting.” Removing low-hanging branches allows better air circulation and reduces the chance of problems with fungal diseases and pests developing.
Propagating Lisbon Lemon Trees
Lemon trees are one of the easiest citrus fruits to propagate from cuttings. These are best taken in late spring or early summer from healthy, new growth that doesn’t have any fruit or flowers yet. It can be helpful to dip the end of the cutting in rooting hormone and make sure it’s potted in a well-drained medium. The medium should be kept moist throughout, and covered with a bag can help to create the desired humid, warm conditions.
Overwintering
Mulching isn’t recommended with lemon trees because they don’t like soggy roots. If you’re expecting frosts, it’s better to keep them in a container that can be moved inside for overwintering. Select a warm and sunny spot indoors if you want your tree to continue producing fruit.
