Lemons are one of the most popular citrus trees to grow. Given their incredible health benefits, you may want to consider growing your own. Do you currently buy conventionally grown lemons rather than organic? If so, be aware that after harvest, they are routinely dipped in fungicide to prevent fungal diseases occurring during storage and when displayed at retailers.

Lemons are also waxed to improve appearance and retain the fungicide. Some are even ‘degreened’ to get them to market before they are naturally yellow. When you touch those lemons, the chemicals used may absorb into your skin. Not appetising thoughts are they?

Whilst citrus trees require higher maintenance than some fruits, if you want to harvest lots of delicious juicy ripe lemons, they’re worth the effort.

5 Reasons Why Lemons may not Ripen and Turn Yellow

If your lemons appear a reasonable size but are still green, rather than turning yellow, this could be due to a number of factors.

1. The Fruit may be Immature

You simply may need more patience! Your lemons may not yet be fully ripe. So just wait a bit longer. Depending on your climate and local conditions, lemons can take up to 9 months or longer to ripen!

Mature lemon trees with heavy crops of fruit require more water and nutrients to sustain growth

My trees often produce so much fruit, we’re still using them from last season while the tree is producing new season flowers.

2. The Tree’s Age and Health

Young lemon trees focus on establishing roots as a priority, so most of the energy is directed into root and leaf growth. It can put a considerable strain on 1-2 year old trees to produce fruit, particularly if they are lacking nutrients. Which brings me to how healthy your lemon tree is.

Is it well fed? Lemons are heavy feeders. They need seasonal nutrients added to the soil or potting mix to sustain healthy, robust growth and sustain fruit development. You can’t expect a starving tree to deliver you a box of luscious lemons quickly! A slightly acidic soil pH, slow release nitrogen-rich organic matter and mulch will all help boost growth.

Immature green lemons on a heavily shaded, nutrient-deficient lemon tree

3. Lack of Warmth and Sunlight

Your tree location may be too shaded. Or the weather conditions may have an impact. Long periods of cold or cloudy weather with little sun and heat can slow ripening down. Frost can severely damage your lemon tree. If your tree is in a pot, you may be able to move it to a sunnier warm spot with better results.

If your lemon tree is in the ground, you may be able to prune it back for better aeration and allow more light in. Or maybe you need to prune or remove neighbouring plants that are competing for sunlight!

During cooler months, lemons become dormant, so be realistic in your expectations too.

Inconsistent Watering

Like all citrus, lemons need regular soil moisture for sustained healthy growth and to produce juicy fruit. If your tree has been drought or heat stressed, in too small a pot with hydrophobic soil or isn’t watered sufficiently, this may be a contributing factor to green fruit.

Lemon trees need regular moisture but rain at fruit set may damage flowers

As your lemon tree grows, so does its need for water! Rain is full of nitrogen and you should see your lemon tree respond well afterwards. A couple of buckets of water might be sufficient for a pot grown lemon, but not a fully grown tree with a big root system.

5. Cultivar and Number of Fruit

Lastly, how long it takes for your lemon tree to ripen depends on the cultivar you’re growing and the rootstock it is grown on. Some varieties are large and others smaller, so they may mature more quickly.

The quantity of fruit on your tree will also have an impact on how quickly your lemons ripen. A heavily laden tree has to spread the nutrient and moisture resources across many more fruit than a small tree. It will also have a high demand for water and unless met, this may slow ripening and result in smaller fruit.

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When will Lemons Ripen?

This depends on your climate and variety. If you live in a cool climate, lemon trees generally form flowers in spring, as the weather warms up. Their fruit usually matures the following winter. Typically, there is one harvest a year and the growth is slower than warmer climates.

In subtropical and tropical climates with mild winter temperatures, lemons tend to continually flower and can produce multiple crops throughout the year. For example, in QLD, NT, WA and northern/coastal NSW, Australia, lemons develop in around 6-7 months. It’s quite common for fruit year round. In southern growing areas of NSW, SA and VIC, fruit is slower to mature, and may take 8-9 months.

In my subtropical climate, I have overlapping harvests with different varieties. When they’re not fruiting, often my limes will be in abundance. Choosing your varieties carefully ensures you have fruit for the longest period possible.

New season buds forming and ripening lemons on the same tree

Colour Changes as Lemons Ripen

Once the baby fruit is ‘set’ after pollination occurs, the lemon will develop and grow over the warmer months.

As each lemon fills out, you will notice the colour start changing from fully green to yellow tinges and finally, full yellow for most varieties. In warmer climates, they may never turn 100% yellow when ripe.

Have you ever noticed the way nature provides us with all that vitamin C rich fruit during seasons when the body needs an immune boost?

How can you tell if Lemons are Ripe?

Lemons ripen best ON the tree, although you can ripen them after picking if needed. When fully ripe, the inner pulp will be filled with juice. As a lemon matures, it reaches optimum sugar content and flavour, as the acids inside decrease and sugars increase.

A mature lemon should have bright glossy skin and feel firm and heavy in your hand. This reflects the quantity of juice.

Healthy mature lemons taste juicy and sweet

A juicy lemon should yield you 40-60ml (1.3 – 2 fl oz) of juice and 2-3 teaspoons of peel. Picking a lemon and measuring these will give you an indication of ripeness too.

Lemons can stay on your tree for several weeks even when ripe, without deteriorating in quality. So, you can pace how quickly you use them. If they start to feel soft or flavour deteriorates, it’s time to pick and refrigerate or juice them. Freeze juice if you can’t use immediately.

Taste Test for Lemon Ripeness

If you’re still not sure whether your fruit is ripe and the skin is still a little green, what should you do? Simply pick a lemon and taste it! It should be flavoursome and juicy. If it’s hard, bitter or the skin is very thick, these are clues you need to pay more attention to the way you are growing your lemon tree.

Tasting the flavour of a lemon and juicing it can help you determine if it’s ripe

Well, I hope this has helped ‘colour in’ the reasons why your lemons may not be turning yellow, so you can make more informed decisions for juicy rewards.

If you need one-on-one help with your citrus trees, contact me for an onsite consultation or live chat and I’ll be happy to provide personalised advice.

Related Articles

• Choosing Fruit Trees for Small Gardens

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