Q&A for How to Grow Lemon Trees Indoors

This method may grow into a tree, but the fruit will likely not resemble the parent fruit. Grafting is how most commercial lemons are propagated.

Providing a support for the heavy branch won’t hurt but it isn’t entirely necessary. The tree will be able to support itself and the growing fruit on its own.

Pruning a citrus tree is not recommended (especially if it is seed grown) as seed grown trees only fruit after reaching a certain high node count, which varies from tree to tree. However, pruning to a certain shape can be done in spring.

If you are watering the trees enough, it could be a sign of lack of nitrogen or phosphorus, so it might be a good idea to fertilize or add compost.

Any bulb made for grow lights will work (often found at nurseries). If you are using a standard lamp, use a "daylight" fluorescent bulb. Incandescent (filament) bulbs do not have the right frequency for the plant to photosynthesize. It could also burn the plant.

Prune off a few leaves at the bottom to reduce transpiration. Make sure that any flower buds/ lemon blossoms are also removed and keep the cutting in water until you are ready to plant it. When you are ready, dip the pruned limb into some strong rooting powder and plant it into free draining ericaceous compost (preferably special citrus compost). Cover the pot with the cutting with a cling film-like material that will keep the pot humid, but will not stick to the plant. Water enough to keep moist, but do not let the cutting sit in wet soil. When it has rooted, remove cling film and treat it like a new plant. If grown correctly, it could fruit in roughly three years' time since rooting.

Many trees take a long time to recover from a severe pruning. Filtering the light some and ideal temperatures may help with the recovery. Also, make sure conditions are suitable for the tree; as ideal temperatures help, temperature extremes can slow the recovery, as can other stressors, such as too much/too little water, improper nutrients, sunburn, windburn, etc. As long as the tree is not dropping its remaining leaves, it is in decent condition.

A lemon tree will only produce fruit after having surpassed a certain high node count, which varies from tree to tree. If this condition is met, the tree can theoretically fruit. This can be achieved in various ways, including subjecting the tree to over 300 'cold hours' (do not expose trees to temperatures less than 10°C) or by withdrawing water until stress induced blooming occurs. The latter occurs naturally in lemon trees' native Asia, where the monsoon provides water after a long drought and causes the tree to bloom. Blooms are complete and self-pollinate, but it is better to pollinate them by hand in the absence of bees. This can be done by using a Q-tip or a fine paintbrush.

A lemon tree has a lifespan of around 100 years to upwards of 300 or 400 years in the ground in an optimal climate. In a pot in, this can range from an average of around 50 years to upwards of 300 or 400 years.

It can take 3 - 5 years on average before a lemon tree will bear fruit.

There are multiple selections grown in Mediterranean areas which differ in size and taste. There are no poisonous lemons per se, though the fruit of some selection may taste bitter, have little flesh or a lot of seeds which makes them more suited for decoration than for the table. There are a lot of excellent Mediterranean lemon varieties however, so it really depends which one you got.

It may have gotten too cold and tried to bear fruit in case it died, or it didn't have enough water so it bore fruit in case it would die, then it lost the fruit and leaves because of a lack of water.

The fruit is probably fully maturing. The reason you are getting smaller lemons is probably because you haven't grafted your lemon tree.

Most definitely. Citrus trees like a lot of water, but cannot tolerate constantly wet feet. Ensure your soil or potting mix drains well.

You should consider changing the pot to a bigger one and placing a plate underneath. Make sure to always remove water from the plate (the roots tend to “seek” water).

You can use normal bamboo canes, just like for ordinary flowers.

California lemon is the only native cultivar; all others were imported from Japan and Mongolia.

Yes. It’s a sucker and will remove nutrients from the rest of the plant. Use alcohol-cleaned shears to cut as close to the base as possible, but make sure it doesn’t get dirt on it. Try to keep the area dry as well, at least until you are confident infection risks are gone.

Some varieties of lemon trees do have sharp spikes. Lisbon lemons are very thorny. Eureka lemons much less so. Meyer lemon trees are also thorny. Most citrus trees are grafted, not grown from seed. You must have planted seeds from a thorny variety but you can clip them off (with sterile pruning shears) or they can puncture the fruit as it ripens and allow diseases to infect them.

Using a magnifying glass, check the backs of the leaves for spider mites or mealybugs. If you see either one, then treat with a gentle pesticide.