Gadenin日本語Get the appWater by weight, not by schedule
The single most common way to lose a potted lime is a watering routine. Once a week is meaningless, because a tree in full flush on a hot windy day drinks three times what the same tree drinks in a cool spell. The tree does not know what day it is.
Learn the pot's weight instead. Lift it, or tip it slightly with a foot, straight after a full watering, and again three days later. That difference is what you are feeling for. Water when the pot has gone noticeably light and the top two inches (5 cm) of mix are dry to a pushed finger. Then water until it runs freely from the base, and empty the saucer within half an hour. A pot standing in water for a day is a pot with dying root tips.
In open ground, soak deeply and infrequently rather than sprinkling daily. A slow hose run that wets the soil a foot (30 cm) down every five to seven days in warm weather beats a daily splash that only wets the surface and keeps the roots shallow.
| Symptom | Most likely cause | What to do |
|---|---|---|
| Leaves cupping upward, dull | Underwatered | Soak twice, an hour apart |
| Leaves yellowing from the oldest first, soft | Overwatered, airless roots | Stop watering, check drainage hole |
| Sudden drop of green leaves | Cold or a sharp move | Stabilize position and temperature |
| Yellow between green veins | Nutrient lock-out or hungry | Feed with a chelated citrus feed |
| Leaf edges brown and crisp | Salt build up or wind burn | Flush the pot with clear water |
Feed the flush, not the calendar
A lime in a warm climate flowers and sets fruit in flushes almost all year, so it is rarely truly idle. Feed whenever new shoots are extending and back off when the tree is coasting. In practice that means a high nitrogen citrus feed at label strength every two weeks through the warm months, dropping to once a month or stopping altogether while the tree is cool and static.
Citrus need more trace elements than most fruit, particularly iron, magnesium and zinc. A feed sold specifically for citrus carries them. A general tomato feed does not, and after a couple of seasons on it you will see the classic yellow patterning between green veins on the newest leaves.
Flush the pot every couple of months in warm weather. Run clear water through until roughly a quarter of the pot volume has passed out of the base. This washes out the salts that regular feeding leaves behind, which are the usual cause of brown crisp leaf edges on a tree that is otherwise well watered.
Never feed a dry pot. Water first, wait twenty minutes, then feed. Fertilizer into dry mix burns root tips, and the damage shows up two weeks later as leaf drop you will blame on something else.
Handle the thorns and the juice with respect
Limes are thorny, and the thorns are stiff enough to go through a thin glove. Wear proper gauntlets when you reach into the canopy. That is the minor hazard. The serious one is the juice.
Lime juice on skin in sunlight causes phytophotodermatitis, a genuine chemical burn rather than an allergy. The furocoumarins in the juice and peel oil react with ultraviolet light and produce redness, blistering and then dark staining that can last for months. It is a well documented injury, common enough that emergency departments recognize it on sight, and it does not require a sensitive skin to happen.
The rule is simple. If you juice, zest or prune the tree outdoors on a bright day, wash your hands, forearms and any splashed skin with soap and water before you go back into the sun. Do not just rinse. If juice has been on skin in sun for a while, keep that area covered for the rest of the day.
Keeping the shape and the fruit load sensible
A lime carries several flushes at once, so you will often see flowers, pea-sized fruit and pickable fruit on the same branch. That is normal and not a sign of confusion. What is worth managing is the load on a young tree. In the first two years, strip most of the fruit off and let the tree build a frame. A three foot (90 cm) tree ripening twenty limes will stall and then take two seasons to recover.
Rub out water shoots that come from below the graft union as soon as you see them, using a thumb rather than pruners. Rootstock growth is vigorous, thornier than the top, and will take the tree over within a season if you leave it. Anything below the union is not your lime.
Turn a potted tree a quarter turn every few weeks so it does not lean into the light and build all its fruiting wood on one side.
What to record
Note the date each flush of new shoots starts, and the date the following flowers open. Over two seasons this gives you your own rhythm, which is far more useful than a generic feeding chart, because it tells you exactly when to raise the feed and when to ease off.
Also log the date you last flushed the pot with clear water, and the date you last repotted or top dressed. Both are easy to lose track of and both show up later as symptoms you would otherwise misdiagnose as disease.