Gadenin日本語Get the appWater deeply and less often
The feeding roots of an orange sit in the top twelve to eighteen inches (30-45 cm) of soil and spread out past the edge of the canopy. Watering has to wet that whole plate, not just a spot at the trunk. A short daily sprinkle keeps the surface damp and the roots shallow; a long slow soak every week or ten days pulls them down where they are safe from a hot spell.
Judge by the soil rather than by the calendar. Push a finger or a screwdriver in six inches (15 cm) at the canopy edge. If it comes out damp, wait. If it comes out dry and the tool went in hard, water. In a hot dry summer that will be roughly weekly in the ground and every two or three days in a large container; in cool damp weather it may be once a month or not at all.
There are two periods when a shortage costs you real fruit. The first is flowering and the few weeks after, when drought makes the tree shed young fruitlets wholesale. The second is the final swell before harvest, when erratic watering after a dry spell splits the skins of the fruit that are nearly ready. Swings do more damage than a steadily modest supply, so aim for even rather than generous.
| Condition | Roughly how often | How much | What to watch |
|---|---|---|---|
| Hot, dry, in the ground | Every 7-10 days | A slow soak to 18 inches (45 cm) | Wilting at midday that recovers by evening |
| Warm, in a large container | Every 2-3 days | Until it runs freely from the base | Pot noticeably light when lifted |
| Cool and damp | Every 3-4 weeks or not at all | Only if dry at 6 inches (15 cm) | Yellowing lower leaves in wet soil |
| Flowering and fruit set | Do not let it dry out | Steady, moderate | Sudden drop of pea-sized fruit |
| Final swell before picking | Even, no long gaps | Steady, moderate | Split skins after a soaking |
| Winter, dormant | Rarely | Enough to stop the roots drying | Soggy soil in cold weather |
Feed nitrogen in splits, and stop before autumn
Oranges are hungry for nitrogen and moderate about everything else. Give the year's nitrogen in three or four splits rather than one heavy dose: the first as growth starts in spring, the second around flowering, the third in early summer, and a fourth in mid summer only if the tree is carrying a heavy crop. Split feeding matches the tree's actual flushes and avoids pushing a single burst of soft growth.
Stop feeding nitrogen well before the weather turns. Late nitrogen produces a soft autumn flush that will not harden before cold arrives, and that flush is also the tissue leaf miner prefers. It costs you frost damage and a pest problem in the same move.
Citrus is prone to iron, zinc and manganese shortages, and these show as patterned yellowing rather than the even pale color of nitrogen hunger. Yellow leaf with the veins staying green is the classic sign. Use a citrus feed that includes trace elements, and if the yellowing persists, check the soil pH before adding anything else; in alkaline soil the iron is present but locked away, and a foliar feed on the new flush works when a soil application does not.
Yellow leaves are not automatically a feeding problem. Wet soil and rotting roots produce the same symptom, and adding fertilizer to a waterlogged tree makes it worse. Check whether the soil is wet or dry six inches (15 cm) down before you reach for the feed.
Remove suckers from below the graft on sight
The rootstock will try to grow its own shoots. They come from the trunk below the graft union or straight out of the ground beside it, and they are usually more vigorous than anything above the join, with larger, coarser leaves, longer thorns and a faster rate of extension. Left alone, they steal the tree. A rootstock sucker can outgrow the grafted top in two seasons and will never carry the fruit you planted for.
Take them off the moment you see them. Rub out soft green ones with a thumb; cut woody ones flush with the trunk or as close to their point of origin below ground as you can reach, without leaving a stub that will simply resprout. Check the base of the trunk every time you water in the growing season. This takes seconds and is the single most valuable minute of maintenance an orange tree gets.
Vigorous upright shoots that arise above the union are a different thing. Those are watersprouts from the fruiting variety and are not stealing anything, though most of them are badly placed. Leave any that fill a genuine gap in the canopy and remove the rest at pruning time rather than in a panic.
Mulch, a clear trunk and natural fruit drop
Mulch two to four inches (5-10 cm) deep out to the canopy edge with coarse compost or bark. It keeps the shallow roots cool and moist and it stops grass, which is a far more serious competitor for a young citrus than most people expect. Keep grass and weeds entirely out of a circle at least three feet (1 m) across around a young tree.
Leave a clear gap of four to six inches (10-15 cm) between the mulch and the trunk. Mulch heaped against the bark keeps it permanently damp, invites collar rot, and gradually raises the effective soil level over the graft union, which is precisely the failure you planted high to avoid.
Expect a heavy natural fruit drop a few weeks after flowering. A healthy orange sets far more fruit than it can carry and sheds most of them at pea to marble size; this is the tree balancing its own crop, not a fault. Water evenly through that period and let it happen. If drop continues past the small-fruit stage and takes larger fruit with it, look at water swings, a sudden hot dry wind, or a heavy scale infestation, in that order.
The records that make next year easier
Note the date the first flush of new growth appears and the date the first flowers open. These two dates move with your particular garden and, once you have two or three years of them, they let you time feeding and pest inspection to the tree instead of to a generic calendar.
Log each feed with the date and roughly how much. It is remarkably easy to feed twice in three weeks and then not again for four months, and equally easy to convince yourself afterwards that you fed regularly. Also record the week of the natural fruit drop and how heavy it looked, so that an unusually severe one next year is recognizable as unusual.