Odlingsår med växthusvärme

Årets säsong innehöll mycket väder av det vackra slaget, därtill en värme av det ovanligare slaget. Det fina vädret började redan i våras och varade till långt fram på säsongen trots att almanackan visade på höst.

Swedish Garden Year in Review – Weather, Plants, and Pests

Based on Eva Wirén

As is often the case, the weather around midsummer proved unstable. However, after a brief cool spell, it turned hot, almost tropical, and exceptionally sunny—many places experienced long stretches of uninterrupted sunshine without a single drop of rain. Meanwhile, certain regions contended with violent thunderstorms and severe flooding, creating highly variable growing conditions across the country.

Early, Confused, and Repeat Blooms

The season got off to an early start thanks to bright spring days, even though nights remained cold and late frosts struck unexpectedly. This led to cold damage in some sensitive species, notably rhododendrons, whose flower buds dried up and turned brown. If leaves are fresh but flower buds are dead and brown, it’s a clear sign of frost damage, especially since these flower tissues are highly sensitive once they start developing. Reports also came in of unusual forsythia blooms, likely also a result of frost.

With the accelerated season, “everything” bloomed before midsummer: mock orange, peonies, beauty bush, and many roses all flowered early. But the season had more surprises. Due to a prolonged warm period and, in some areas, extreme drought, many plants experienced a second flush of flowers late in the summer. Elderflower and ripe elderberries appeared side by side. Cherry laurel bloomed again, and apple trees were heavy with fruit while simultaneously bearing springtime blossoms. This was certainly a banner year for blackberries, autumn raspberries, and tayberries—yielding rich harvests and extended picking.

Fruitfulness—and Fruit Mold

It was both a good and a challenging fruit year. Apple harvests were abundant, and many varieties ripened a week or two earlier than usual. The rowan moth spared apple crops—thanks to a plentiful supply of rowan berries, its preferred food source, this summer.

However, gardeners across the country noticed large quantities of rotting fruit. The main culprit was fruit mold (fruktmögel, gul monilia), a common fungus that recurs in home gardens most years (Fact Sheet 75T, “Fruktmögel”), especially in warm, wet conditions or where fruits touch each other. The mold infects fruit via wounds, quickly passing from one fruit to another. Affected fruit shows brown spots with yellowish-white fungal dots and can cling to the tree well into winter. To counteract this, thin the fruit (kartgallra), prune trees for better air circulation, and promptly remove all diseased fruit—both from the tree and the ground. Don’t forget to check fruit in storage, as rot can spread there too. Note that stone fruits like plums are especially susceptible to fruit mold.

Common plum problems this year included the plum sawfly and the plum moth (Fact Sheet 156T, “Plommonvecklare och plommonstekel”). Both pests have larvae that develop inside the fruit, causing it to fall prematurely. Sawfly larvae overwinter in the soil, while plum moth larvae may also overwinter under bark. Combat these pests by placing a tarp under plum trees (starting as early as the blossom period) and removing and destroying fallen fruit daily. Shaking the tree can also help dislodge infested fruit.

Aphids on the March

Aphids thrived in this year’s heat, reproducing rapidly. Their sucking activity resulted in curled, twisted, and sticky leaves, slowing new growth and stressing young fruit trees in particular.

Many have asked where so many aphids come from. Some hatch from eggs laid in autumn, while others migrate as winged adults from their overwintering woody hosts to summer hosts. Aphid species with this lifestyle are called host-alternating, regularly shuttling between specific plant species (Fact Sheet 59T, “Bladlöss”).

Aphids can appear in huge numbers due to both favorable weather and their remarkable reproductive strategy—many reproduce by parthenogenesis (“jungfrufödsel”), producing successive generations of females without the need for mating. Additionally, some generations develop wings, allowing aphid populations to spread quickly if their food source becomes crowded.

Aphid outbreaks are reasonably manageable if tackled early. Check plants regularly, use horticultural oil or other approved plant-care products, physically squash aphids or remove infested leaves and shoots. Sometimes, even a strong blast of water is enough. After a severe aphid season, it may be wise to treat affected trees and shrubs in early spring with a mineral oil spray at bud break (Fact Sheet 2T, “Växtskydd i fritidsodling”).

Swedish–English Plant Glossary

Swedish	English
växter	plants
blommor	flowers
frukt	fruit
bladlöss	aphids
mögel	mold
fläder	elder
lagerhägg	cherry laurel
rododendron	rhododendron
schersmin	mock orange
pioner	peonies
paradisbuske	beauty bush
rosor	roses
björnbär	blackberry
hösthallon	autumn raspberry
björnhallon	tayberry
plommon	plum
plommonstekel	plum sawfly
plommonvecklare	plum moth

Key Control Measures

Thin fruit and prune trees for good air movement to prevent fruit mold.
Remove and destroy all fallen or infected fruit from trees and the ground.
Regularly monitor for aphids and treat with horticultural oil, approved sprays, or simply remove by hand or water jet.