If there’s one plant that everyone wants to grow, but is more prone to pests and disease than almost anything else, it’s the lemon. There was a time when every backyard had one, and now, with the introduction of dwarf “patio” forms, every backyard wants one. The list of afflictions though, rivals the Book of Job.
Grow a lemon and you’ll probably need to deal with citrus leaf miner, stink bugs, borers, spined citrus bugs, caterpillars, scale, sooty mould, citrus gall wasp, melanose, citrus scab, a plethora of nutrient deficiencies, frost, drought, brown rot, fruit fly, various root rots and collar rot.
Why would you bother? The irony is that if you get conditions right, lemons are actually quite easy to grow. Healthy plants have enough vigour to resist the majority of pests and diseases, and who can resist the allure of a decent sun ripened lemon that hasn’t been imported from California or China, but is picked fresh from your own backyard.
I know I can’t. When I moved to Thistlebrook, a lemon tree was one of the first plants I purchased, though my climate isn’t ideal and I’ve had to deal with some of the problems listed earlier. I persist though, and as I write my three year old tree is laden with ripening fruit.
The starting point with lemons is the soil. Citrus demand three things in particular – good drainage, constant moisture, and high fertility. This means that black soils aren’t ideal despite their high fertility, and gravely soils like those found in granite country generally lack the “guts” to produce healthy growth. Red soils like those found in Toowoomba and along the escarpment are better options, but if the clay content is high, the addition of decomposed organic matter and gypsum will be of great benefit.
If your soil isn’t ideal there’s always the option of growing a lemon in a large tub. Half wine barrels and big terracotta pots are perfect, though whatever container you choose make sure there are adequate drainage holes in the bottom. Use good potting mix and incorporate some soil to bulk it up. Go for a miniature cultivar like ‘Lots A Lemons’ or a regular cultivar grafted onto a dwarf rootstock like Flying Dragon.
If you’re planting in the ground, prepare the site well. Dig a good sized hole about 60cm deep and wide, and backfill with a mix of soil and rotted manure. Water everything in with seaweed solution, mulch with sugarcane or lucerne, and make sure your new lemon tree doesn’t have to compete with the lawn for nutrients and water.
Lemons are greedier than a Wall St fat cat. I fertilise once per month with fish emulsion, and top dress at least once per year with poultry manure or something like Dynamic Lifter for citrus. If you’re game, wee around your tree as well. There’s plenty of truth to the old saying “Ask the gentlemen of the house to say good evening to the citrus”, but to avoid root burn, tip a bucket of water around the tree as well. Finally, keep the tree in tip top condition by applying a foliar spray of seaweed extract.
For those of you who are like me and have a million jobs in the garden that all needed to be done yesterday, it’s likely that your lemon tree will encounter problems. Minor issues like scale, sooty mould and leaf miner can be easily controlled with horticultural oil. I like to use a plant-derived product rather than one based on petroleum, and when I spray I make sure the entire plant is covered, including the undersides of leaves and the branches. A preventative spray once per month is prudent, and it’s important to avoid spraying oil on hot days. Unless you like to eat fried lemon leaves.
Another common problem is nutrient deficiency. The simplest treatment is to apply a general trace element mix, which will cover as many bases as possible. If you’re keen, diagnose a specific deficiency and treat accordingly. Some typical deficiencies are magnesium and iron, but a lot of people mistake nutrient deficiency for nitrogen deficiency. If your lemon tree has yellowing leaves, feed it with liquid fertiliser. Then a month later feed it again, and if yellowing persists, feed it some more. If yellow leaves still persist, go the trace elements.
When it comes to lemons, the horticultural principle of strongly growing plants resisting problems really rings true. Get the conditions right in the first instance, keep the moisture up during summer and feed. Lemons might be a backyard staple able to tolerate neglect, but they’ll look and crop better if your treat them with care.
First published in the Toowoomba Chronicle 9th May 2009. Image by Joselito Briones.
{ 4 comments… read them below or add one }
Hi Justin, We planted a mandarin tree back in November and I have just put some bricks around it, as a boarder, to stop grass growing to close to the trunk. Is this a good idea. Would stones be better. Regards Jo Williams.
Hello Jo,
With some warmer weather the grass has started growing a a decent rate of knots and runners of kikuyu and couch will steadily take over garden beds unless they’re controlled. Unless your brick border is a couple of rows deep and mortared in, the grass will simply grow under and through the gaps. Stones would probably be even more attractive to the runners.
This leaves a few options. One is to control the grass with a herbicide such as glyphosate (Roundup etc). This will do the trick for a few months, but being an organic gardener I prefer to avoid chemicals if possible. A better option might be to manually remove the grass runners, then create a simple “spade edge” by cutting off any new growth with a sharp spade. Mulch the soil beneath the tree with sugarcane to discourage weeds and keep the soil moist and cool. The other option would be to install a weed barrier to stop the runners invading the bed. This will need to be about 200mm deep and must be gap free. Sleepers are cheap and work well.
Hope that gives you a few ideas.
Cheers,
Justin
Love the way you write! I now realize that we’ve been sorely neglecting our lemon tree (very little fertilizer, sporadic watering and no spray) but in spite of everything, we had a great crop of lemons last year.
This year, however, we have fewer lemons and I notice they all have damaged areas on the skin. Are they going to be edible?
Hi Marisa,
It sounds as though your lemons have a fungal disease called citrus scab. This is very common, particularly during wet weather, but it doesn’t affect the eating quality of the fruit too badly. The rind won’t be very useful, but the flesh is definitely edible! To control scab you could apply an organic approved, copper hydroxide fungicide (such as Kocide or Fungus Fighter) in October.
Cheers,
Justin