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Crops · the long game

Tree crops

Two seasons at once Episode 8 8 min read

The short version

A tree crop goes through the same stages as a bean, and the same fundamentals apply. What changes is time. Its cell division window runs for weeks, not days: probably three to four, Steve says, for limes and avocados. And a tree carries one season into the next. It wakes in spring on what it stored the year before, and in many tree crops next season’s flowers start forming while this season’s fruit is still on. So the season doesn’t end at the pick. What the tree gets back after harvest, and how hard this season works it, both show in next year’s crop.

A lime branch carrying two seasons at once: ripe fruit, and beside it the next crop’s flowers and fruitlets.

The same fundamentals

Steve says it of every crop: “The fundamentals are the same. Doesn’t matter what crop you talk.” A tree flowers, sets its fruit, makes the fruit’s cells, fills them and finishes, the way a bean does. The critical stages are the same idea, and so is the order: the three amigos before the cells divide, and potassium after, once it’s earned.

What changes is time. A bean crop is done in about ten weeks. A tree lives through one season into the next. Vines and bushes that come back each year, like grapes and blueberries, follow the same two-season pattern. Each crop keeps its own timing.

Calcium. Boron. Silicon. Potassium.

  • A bush bean’s flower stalk with four small white-and-lilac flowers open, beside a trifoliate leaf.

    Flowers

    a bean, done in about ten weeks

    calcium, boron and silicon first, before the cells divide

  • The same stalk: three flowers have set thin young pods, and the fourth has dropped, leaving a bare stalk.

    Sets, and makes its cells

    the same bean

    the pods set, and make their cells

  • The same stalk: three long, plump green pods hang down, and the fourth stalk is still bare.

    Fills, then finishes

    the same bean

    potassium after the three, once it’s earned

  • An apple spur at bloom: a rosette of young leaves round a cluster of flowers, the king flower open in the middle, white flushed pink, and five round pink buds around it.

    Flowers

    an apple, through one season into the next

    calcium, boron and silicon first, before the cells divide

  • An apple spur a few weeks after bloom: six small green fruitlets, the one in the middle the biggest and round, among young leaves.

    Sets, and makes its cells

    the same spur

    the fruit sets, and makes its cells

  • The same spur at harvest: one big, ripe red apple hanging where the biggest fruitlet was, among full-grown leaves.

    Fills, then finishes

    the same spur

    potassium after the three, once it’s earned

The fundamentals are the same in every crop. A tree flowers, sets its fruit, makes the fruit’s cells, fills them and finishes, the way a bean does, and in the same order: calcium, boron and silicon before the cells divide, and potassium after, once it’s earned. What changes is time: a bean crop is done in about ten weeks, and a tree lives through one season into the next. An illustration, simplified.

Weeks, not days

Steve’s rule of thumb: in beans, the cell division window is about seven days, or even three or four days. In orchard crops, like limes and avocados, it’s probably more like three to four weeks.

A longer window isn’t an easier one. Calcium gets into the fruit mostly with the water, and it stays where it lands, so it has to keep coming the whole time the cells are dividing. That’s weeks of keeping it coming. In avocados it goes on even longer, because the fruit keeps making cells as it grows, though more slowly. A hot or dry spell in the middle costs quality you can’t put back later. The Stress and salt page has more.

Water, carrying calcium. Calcium missing.

  • The end of an avocado branch at fruit set: two dark green older leaves, a flower spike with three small green fruitlets, and from its tip a flush of soft, bronze-red young leaves.

    Kept coming

    an avocado at fruit set, through its window

    calcium gets in with the water and stays where it lands, so it has to keep coming the whole time

  • The end of an avocado branch at fruit set: two dark green older leaves, a flower spike with three small green fruitlets, and from its tip a flush of soft, bronze-red young leaves.

    Instead, a dry spell

    the same window, a hot spell in the middle

    less gets in while it lasts, and the quality it costs can’t be put back later

A longer window isn’t an easier one. Calcium gets into the fruit mostly with the water, and it stays where it lands, so in tree crops it has to keep coming for three to four weeks, the whole time the cells are dividing. A hot or dry spell in the middle costs quality you can’t put back later. An illustration, simplified.

“Here’s the thing with cell division. Orchard crops, or other crops like limes and avocados, they probably have more of a three to four week window.”

— Steve, on cell division in tree crops

Two seasons at once

In many tree crops, next season’s flowers start forming while this season’s fruit is still on the tree. In apples and stone fruit, next spring’s flower buds form over summer, as the fruit fills. In avocados and citrus, they form through autumn and winter. A lime can carry ripe fruit and its next crop’s flowers on the same branch.

So the tree is working on two crops at once. Ask too much of it this season, with a heavy crop or a hard summer, and next season’s flowers can go short too. On the Crop Walk, that’s the buds check: plenty of buds, plump and even across the block.

Sugar. Sugar spent.

  • A short apple branch in early spring, one spur opening a cluster of white, pink-tipped blossoms.

    Spring

    the savings spent

    the buds, flowers and first leaves run on what the tree stored

  • The same branch in summer: a half-grown apple on one spur, and a plump flower bud forming on the other.

    Summer

    two crops at once

    the fruit fills while next spring’s flower buds form beside it

  • The same branch after the pick: the apple gone, the leaves still green, the flower bud plump.

    After the pick

    the savings rebuilt

    the leaves keep working, and refill the savings for next spring

An apple tree spends its savings in spring, works on two crops at once in summer, and rebuilds its savings after the pick. An illustration, simplified.

The tree’s savings

A tree keeps savings: sugar and minerals stored in its wood and its roots. In spring it spends them on the buds, the flowers and the first leaves, before those leaves are big enough to pay their own way. So how well a tree flowers and sets this spring was partly decided last autumn. In the program builder, an apple’s season starts there: the tree wakes on what it stored.

After the pick

Harvest isn’t the end of a tree’s season. Once the fruit’s off, the leaves keep working, and what they make now goes into the savings for next spring. Keep them healthy for as long as they’re on the tree. A tree that loses its leaves early, to drought, disease or going hungry, starts the next spring short. That’s why most of the program builder’s tree seasons end with a stage after the harvest, to give the tree back what it spent. Nitrogen comes first in them all, with boron and zinc in most.

Sugar.

  • An apple branch after the pick: the apple gone, the leaves still green, the flower bud plump.

    Leaves kept

    an apple branch after the pick

    the leaves keep working, into the savings for next spring

  • The same branch in early spring, one spur opening a cluster of white, pink-tipped blossoms.

    Next spring

    the same branch

    it wakes on what it stored

  • The same branch after the pick, most of its leaves gone, the few left yellow-brown and curling.

    Instead: leaves lost early

    after the pick, on a tree that lost its leaves

    drought, disease or going hungry took them: little goes into the savings

  • The same branch the next spring, with only two or three small flowers.

    Next spring

    the branch that lost its leaves

    it starts the spring short

Harvest isn’t the end of a tree’s season. Once the fruit’s off, the leaves keep working, and what they make goes into the savings for next spring. A tree that loses its leaves early, to drought, disease or going hungry, starts the next spring short. An illustration, simplified.

Nitrogen has two jobs at either end of the pick. As the fruit finishes, it’s held back, so the tree puts its effort into the finish and not into soft growth. Once the fruit’s off, it goes back on, into the savings for next spring’s start.

On years and off years

Push a tree to carry too big a crop, and it can pay for it next season with a light one. The heavy crop spends the savings, and while it hangs, fewer flowers form for next year. Some trees fall into a rhythm of on years and off years: avocados, mandarins and some apples are known for it. Evening it out starts with a crop the tree can carry, and savings rebuilt every year. In apples, that’s why growers thin a heavy set.

Sugar. Sugar spent.

  • A mandarin branch bowed under a heavy crop of crowded, ripe orange fruit.

    An on year

    a mandarin branch, at the pick

    the heavy crop spends the savings, and fewer flowers form for next year

  • The same mandarin branch in spring, its fruit picked: only three small clusters of white flowers along it.

    The spring after

    the same branch as the on year

    few flowers, so a light crop: an off year

  • The same mandarin branch carrying just five ripe mandarins, well spaced.

    A crop it can carry

    the on year’s branch, at the pick

    fruit this year, and savings left for next spring’s flowers

A tree pushed to carry too big a crop pays for it next season: the heavy crop spends its savings, and fewer flowers form. Evening it out starts with a crop the tree can carry. An illustration, simplified.

Roots that stay

An annual row crop’s roots die at the end of its season. A tree’s stay in the same ground for years, so the soil under it is built up, or run down, season after season. Steve’s line holds here too: if you want your soil to change, you’ve got to put a plant in there. The Soil health page has more.

In an orchard, the trees are only some of the plants. The mulch on the row feeds the life around the roots, and a living cover between the rows keeps roots in the ground all year.

The soil’s life. A fungus’s threads.

  • A cut-away of a young apple tree in an orchard row, bare, pale soil on both sides, and only the tree’s roots below.

    Bare ground

    an orchard row

    only the tree’s roots, and the soil under it runs down, season after season

  • The same tree with woodchip mulch beneath it and a low cover of grasses and clover between the rows, their fine roots in the darker topsoil.

    Mulch and a living cover

    the same row

    the mulch feeds the life round the roots, and the cover keeps roots in the ground all year

A tree’s roots stay in the same ground for years, so the soil under it is built up, or run down, season after season. Mulch on the row feeds the life around the roots, and a living cover between the rows keeps roots in the ground all year. An illustration, simplified.

Reading a tree

  • Sap test the same trees each time, the same leaves, at the same time of day, so the trend means something. The Sap testing page has more.
  • Read this season against last season, stage by stage. A tree gives you the same stages every year to compare.
  • Count and size the fruitlets on the same branches each walk: the count is your set, and how they grow shows the window at work.
  • Look at next season’s buds while this season’s fruit is on.

Where it fits in a program

  • Plan the year, not just the crop. In the program builder, avocados, apples, stone fruit, citrus, grapes, tree nuts, tropical tree fruit and berries each run a year from the start of the season, not from a sowing date.
  • Pour the foundation before the cells divide, and keep the calcium coming through the weeks they divide.
  • Look after next season’s flowers this season: boron and zinc on time, and stress kept down while the buds form.
  • Give back after the pick, while the leaves are still working.
  • Sap test at the stages your program marks for one, and compare with last season’s.
  • Rates come from your tests, your agronomist and the label. Never a guess.