How a tree's photosynthesis changes through the year, from leaf-out to leaf fall
When trees photosynthesize most, how a new leaf spends stored sugar before it earns any, what drought and short days do, and what evergreens do in winter.
Topic
How trees work
Articles on how trees work: dormant buds, bark that photosynthesizes, roots that survive floods, red new leaves, the defenses trees keep, and a glossary.
The physiology behind the advice elsewhere on the site, with the terms gathered in the glossary. Every species we grow has its own page with the facts that follow from it: zones, mature size, sun, soil and what to expect.
Articles tagged How trees work
Organic or synthetic fertilizer: how they differ and what a tree needs
Why a root takes the same nutrients from either bag, how organic and synthetic fertilizers differ in release, salts and soil life, and when a tree needs any.
Burls: what makes the big knobs on a trunk, and do they harm the tree?
What makes knotty burls grow on oak and maple trunks, why cutting one off hurts more than leaving it, and how to tell a burl from a gall or canker by the bark.
Is my bald cypress dead? The conifers that drop every needle in fall, and when brown means trouble
Why a bald cypress turns brown and bare each fall, what browning in summer means, how pines and spruces shed old needles, and how to tell if the tree is dead.
Twigs all over the lawn: squirrels, twig girdlers, or a tree shedding its own twigs
Why oaks drop small branches in summer and fall, how the cut end shows whether a squirrel, a beetle or the tree itself did it, and what to do with the twigs.
Why a tree flowers but bears no fruit: it may be a male, lack a partner nearby, or be too young
Why a holly has no berries or a persimmon bears nothing, how to tell male flowers from female, how many seedlings to plant, and when frost or shade is to blame.
Sun leaves and shade leaves: why one tree grows two kinds of leaf, and what it means for a seedling moved into shade
Why a tree grows sun leaves and shade leaves, why a young tree scorches after a move into sun or stalls in shade, and learning light tolerance before planting.
Winter identification: telling native trees apart by bark, buds and twigs
How to identify a tree in winter by its bark, buds, twigs and pith, where the opposite-branching shortcut fails, and a table of winter signs for native trees.
Seed source and provenance: why where the parent tree grew decides how yours will do
How far tree seed can move north or uphill, why seed source changes how a tree grows, what trials and seed zones show, and what to ask a nursery before buying.
Tree roots run shallow and wide, not deep: what that means for watering, mulch and the house
How deep and wide tree roots grow, why the taproot fades, where to water and mulch, what trenches and fill do, and how far from a house to plant a tree.
Mast years: why oaks, hickories and beech bear a huge crop one fall and almost none the next
Why oaks, hickories and beech crop heavily in some years, how red and white oaks keep separate calendars, what mast does to wildlife, and when to collect seed.
Why leaves turn red and yellow in fall, and which native trees give each color
Why fall leaves turn yellow, orange or red, what the red protects, how frost, drought and a warm fall change the show, and which native trees give each color.
A glossary of the words we use about trees
134 tree terms in plain words, from abscission layer to tylosis: root flare, included bark, marcescence and mast, most linked to the article that explains it.
How floodplain trees survive high water
Why standing water kills roots, how bottomland trees get air to theirs, what cypress knees do, why fill kills an upland tree, and what to plant in a wet spot.
Photosynthesis without leaves: the green layer under bark
Where the green layer under bark sits, why wet bark shows it, how much of what it fixes is carbon the tree itself has respired, and when it matters most.
Epicormic buds: the sprouts that appear after damage or new sunlight
Trees carry sleeping buds in their bark for decades. A broken top, hard pruning or sudden sun wakes them. What the sprouts mean and what to do with them.
How trees defend themselves
Trees cannot run, so they fight with resin, thorns, tannin, latex, thick bark and stump sprouts. A tour of the defenses, with the debated parts flagged.
Leaf litter, not wood chips, under the canopy
A forest floor of leaves, twigs and fruit feeds a tree and holds water in ways a wood-chip bed cannot. How to build one in a yard, and where chips still belong.
Marcescence: why young beeches and oaks keep their dead leaves all winter
The copper-brown leaves rattling on beech saplings and young oaks in January are marcescence. What it is, why it might happen and why it needs no action.
Multistem or single stem? Sometimes the trunk is hiding the answer
A trunk that looks like one stem can be two or three that grew together with bark trapped inside. How clumps form, why fused trunks fail, and what to do early.
Pruning at the branch collar, and when to make the cut
Cut just outside the branch collar, never flush and never leaving a stub. How to find the collar, use three cuts instead of one, and pick the right season.
Wasp galls on oaks
Oak apples, bullet galls, wool sower galls and woody twig knobs are all grown by the tree around a tiny wasp. They look like disease and almost never are.
When oaks leaf out, and why two of them never agree
The order in which an eastern woodland leafs out, why two oaks ten feet apart can break bud two weeks apart, and how to tell a late oak from a sick one.
Fungus on a tree is not a death sentence
Hollow trunks, torn-out limbs and shelf fungi look like the end. Trees can live for decades or centuries in that state, and here is how to tell when it matters.
Why new leaves come out red
That bronze-red flush on spring oak and maple leaves is anthocyanin, a sunscreen, not stress. Here is what the pigment is doing and when to actually worry.