Citrus Trees - Lemons & Limes- How to keep them healthy and happy, even in winter.

There is nothing quite as gratifying as picking homegrown lemons from your own lemon tree, to make your famous lemon mousse cups for Easter dinner, or to dress your salmon and squirt on your asparagus.

Location, Location, Location

My lime and lemon in November in a south facing window.

Location is everything, in both winter & summer

WINTER- Citrus trees usually do their flowering and fruiting in fall and winter so you really want the ideal spot for them when you bring them into the house or greenhouse.

My two citrus trees, a Key lime and a Meyer's lemon, have been sitting in a south facing window in the grandkid's room since October and seem to love it in there. Both have put on new growth, some fruits, and lots of flowers. Usually citrus tend to survive indoors but not really thrive, so I am very pleasantly surprised.

I think the sunny prairie winter days make all the difference. I turned off the heating vent to keep the room a bit cooler, with no warm or cool drafts.

If you live in the grey PNW and want to bring your citrus indoors, pick a cool place in your home, a spare room maybe? Make sure it is not by a heating vent, wood stove, opening slider door, or any other drafts, and definitely use grow lights to brighten those grey rainy days. Bright is the key!

They also want it cool , not hot, not drafty. In winter, citrus trees prefer to be on the cooler side, ideally around 10°C but anywhere from 5° to 15°C (40° to 60°F) is great. In the heated greenhouse, I used to keep the heater at about 5°C degrees and they thrived. In late winter and spring, I kept them around 10°C, which was not possible in the dead of winter as it was cost prohibitive. These ones here in the window are about 15 ish, even with the vent closed, also thriving.

SUMMER - Potted lemons and citrus trees do not want to be out in the blazing hot from dawn till dusk. Find a spot that gets morning sun and then dappled during the hot afternoons, or dappled during the day and full on in the evening sun. They like lots of sun but not the full-on hot sun from dawn till dusk. Put them under your apple trees for dappled shade, on your deck, on the east or west facing patio. They will thank you for the bit of a breather.

The same lime and lemon in late March, now living in the shower stall.

SPRING - My lemon and lime are now living in the en-suite shower stall. This is a shower that we no longer use now that we have the sauna and new shower room so is the perfect place for them to hang out till they can go back outside for the summer. Is bright, cool, and they are away from heating vents and all drafts. I can water and spray the foliage to my heart's content!

When Can They Go Outside? - Your citrus can go outside when night time temps are just above zero, so I am thinking May here on the prairies, haha, but right about now on the west coast. I will put mine out into the wee greenhouse in April, when I start heating it so that it stays just above zero at night. Citrus can handle a light frost on the foliage, so if it were to happen, do not fret, they will be fine.

HARDENING OFF- When you bring them outside, from in the house or greenhouse, you want to acclimate them to the new conditions. Out in the shade for the first few days, not full sun, and bring them in for the night if there is a big temperature difference from where they were to where they are going.

In the zone 7, I took them from the heated greenhouse to the unheated one for couple of weeks first, to acclimate, and then put them outside on a grey day. If you have no greenhouse to put them in, put them in the gazebo, on the covered porch, someplace where they do not get full sun right away or you will get sunburnt leaves and they will fall off.

My Meyer's Lemon in January, heated greenhouse.

Watering & Feeding

Keep them on the dry side. Water only when the top few inches of soil is dry. If I stick my finger into the pot and the soil is dry, I will water thoroughly, but if it still feels moist, I wait a bit longer till I water. Do not leaving them sitting in a saucer of water. Citrus do not like wet feet. If they are over-watered, too cool, and/or not bright enough, the leaves will start to curl under. Too wet and they will start to drop their leaves. They don't like bone dry but they don't like wet. I always err on the side of drier soil.

In winter, I am watering every 2 to 4 weeks, depending on the how fast the soil dries out. It is not in an active growth time and the days are shorter, so less water needed. In summer, I am watering sometimes every second day. Don't be afraid of sticking your finger in the soil.

In spring, you want to flush out the salts that build up in the soil from regular watering and fertilising throughout the year. Run the water till you see the water running freely from the bottom. I will do this 2 or 3 times. You can wait till you take them outside if you do not feel like hauling them into the shower ; )

How you feed them really depends on what kind of fertiliser you can find, but they like a high nitrogen fertiliser (first number), with about twice the nitrogen to the phosphorous (middle number).

Never fertilise with a water soluble fertiliser on dry soil. They say not to feed your limes if they look healthy as the feed is not necessary and may instead make them unhappy.

I have been using this water soluble citrus and evergreen fertiliser (30-10-10) now and again, and they are doing really well on it. You can give this to them once a month from spring through fall, taking a break for three months from November through till February. If your leaves are very yellow or limey in colour (new growth is always lighter in colour, they are not a worry), this should do the trick to start greening them up again.

General feeding - If you are able to find a slow release fertiliser meant for citrus, yay! The one I used to use was discontinued and I miss it! Follow the directions on the container, it is usually applied every 6 weeks during the growing season.

When they go outside, I give them a top dressing with manure or compost and mix in some kind of slow release fertiliser. I really like Acti-Sol hen manure pellets (It is a 5-3-2). I use this for tomatoes, garlic, any kind of food crops, roses, and have heard you can even use it on lawns, if you happen to be a lawn person. (This is also what I would feed rhubarb, fruiting trees and shrubs, ornamentals, too). You can also use this as a slow release fertiliser year round, as needed.

Top dress citrus trees with manure/compost/nutrients.

If you cannot find Acti-Sol, you can mix a bit of blood and bone meal to the top dressing instead. I have often just fed them with liquid seaweed and a few dressings of compost per year, too, and they thrive just fine.

Worm castings added to your manure is also a great organic feed, at 10% strength. So, if you make a mix to give all your plants, put 9 scoops of potting soil into a bin and 1 scoop of worm castings. Mix it about and top dress your potted plants.

The same lemon taken a few months earlier (November), many unripe lemons and lots of flowers.

Pollination

Citrus flower and fruit mainly in fall and winter time while there are no bugs around so you may need to help them out to ensure that you get fruits! Take a q-tip, paint brush, or small battery powered toothbrush to vibrate each blossom, go from flower to flower.

The same lemon tree year earlier. In the same pot.

Potting Up & Repotting

When you buy your citrus tree, take it out of the plastic pot and put it into a nice clay/terracotta pot. Plastic holds in moisture and citrus really dislike wet feet. Clay pots breathe and dry out faster so the citrus thrive.

How I figured this out - I had two little lemon trees left on my nursery floor that had not sold in spring. I decided to keep one for myself, and being a bit of a clay pot snob, hah, I put my lemon into a pretty terracotta pot and left the one I was going to sell in the one litre plastic pot. They sat side by side in the nursery, in the shade during the afternoon, and by end summer, my lemon had more than doubled in size compared to the one in plastic. Live and learn everyday! Since then, my lemons (and olives) have always lived in clay pots.

You should usually not have to repot your tree more than every 3rd or 4th year, depending on how fast it is growing. Often times, you can root prune and leave it in the same pot, not having to upsize till later. Once my trees got to my biggest pots (see the picture of them outside all in a row), I just root pruned every 3rd year, freshened up the soil, and put them back into the same pot.

Pruning and repotting should be done when there are no flowers or fruits on the tree, which is usually in late spring.

This root pruned potted plant, plus instructions from Stark Insider.

Root Pruning - I find this easiest to do with a helper. Pull the lemon tree out of the pot, have someone hold it for you while you prune, or lay it down carefully on a tarp while you work on it.

- Pull off the bottom third of the roots. These roots will be small, sometimes white and soft, will come off easily with your fingers. If it is really root bound, do not be afraid to use the blade of your pruners to start digging into the root ball and loosening it up. I have never had mine be as root bound as the plant in the picture above, but you can see that he basically just pulled it off, cutting as needed. I do not cut into the thicker roots, just leave them be, but if they are really long, you can shorten them up a bit.

- Rub some of the soil off of the entire root ball.

- Dump out the old soil (into the compost bin is great). Fill up the bottom of pot with fresh, new soil. I use my 'secret' recipe of 5 parts potting soil to 2 or 3 parts of manure or compost. If you happen to have composted pine bark, you can add one part of that, too, but never use fresh bark. It must be the composted stuff.

- Put the plant back into the pot, fill the edges with your new soil mix.

Good to go for another three years.

These branches were too long so were weighted down with the oranges. After harvest, we shortened them by 2/3.

Pruning Branches - Dwarf citrus, especially Meyer's lemons, do not tend to need a lot of pruning but if you give it a going over once a year, or every couple of years, it will make for a happier, better producing tree.

Take off any dead branches, any really skinny wee branches coming off of the branches or main stem, crossing branches, and upwards growing water sprouts.

Always remove growth from below the graft, that will be rootstock. If you see a zigzagging branch, that is rootstock, you want to remove it.

If you have branches growing in towards the middle of your tree, prune those out.

Last would be to shorten branches that are too long for better shape. It will promote new growth, better fruiting, and keep it more compact. Cut just above an outward facing bud so that the new growth grows out rather than in towards the center of the tree.

Here you see Soft Scale in the creepy crawly stage and also with the shell over top of it already.

All About Bugs

Citrus are prone to soft scale but are rarely bothered by other bugs, though you may get aphids or whitefly now and again.

Spraying for bugs on citrus (and indoor plants) is a 3-step process. I will do this a few times before they go outside for the summer. I do not spray outside as I may be killing off beneficial insects or pollinators.

1. Hose off plants with a strong jet of water. If you have scale, make sure to do the stems and branches really well to get rid of them while they are still at the creepy crawly stage (see the picture above).

2. Spray thoroughly with End-All or Trounce, making sure to get stems and undersides of leaves. Let sit for 15 to 20 minutes.

3. Rinse off the residue and dead bugs with a strong jet of water. This strong spray does not hurt the plant, just cleans off dead leaves, bugs, and debris.

This is not going to get rid of scale on the leaves and stems as the bug is protected by that shell they have made. You will need to rub or wipe those off with a cloth or soft scrub brush. Grab a bucket of warm, soapy water, a soft brush, and a cloth. Scrub the branches with the brush, wipe the leaves with the cloth.

I usually go along and squish or scrape them off with my fingers before I go along with the brush. It is gross, very gross. You can also use baby bum wipes on the leaves.

Keep in mind that if you hose off the stems each time you water, you will be blowing most of them away before they can build that shell.

Tips - Bearss or Key Lime, Eureka Lemon, Pink Variegated Eureka Lemon, and Meyer's Lemons are the best for growing in pots. You can also grow oranges and mandarins, plus there is now a new dwarf grapefruit, also.

Lemons grown from seed will rarely produce fruits and if they do, they will not likely be true to form, or tasty.

Happy citrus growing!

Tanja