Flowering Quince

Feed sparingly, and go easy on the nitrogen

Flowering quince tolerates a wide range of soil and rarely needs feeding. If you feed at all, keep nitrogen low. If the leaves turn yellow while the veins stay green, read that as iron chlorosis from alkaline soil, not hunger - correct the pH rather than adding more fertilizer. Excess nitrogen pushes soft succulent shoots, and succulent growth is what fire blight infects most easily. Separately, this shrub tolerates a wide range of soils except very alkaline ones, which cause iron chlorosis that no amount of nitrogen will fix; Virginia Cooperative Extension pub 2901-1044 puts its workable pH range at 3.7 to 7.0.

Renewal prune as soon as the flowers finish

Once the last petals drop, cut about a third of the wood to the ground, taking the oldest branches and any weak twiggy growth first. If you want fruit, go lighter than that; if you only want flowers, this shrub tolerates hard pruning. Flowering quince blooms on old wood and sets next spring's flower buds over the summer, so the window between petal fall and bud set is the only time you can cut without throwing away next year's bloom.

⚠ The stems of most varieties are thorny and interlace densely - wear leather gauntlets and eye protection when reaching into the crown.

Cut out fire blight cankers while the shrub is dormant

Walk the shrub while it is leafless and look for blackened, sunken cankers and dead twigs. Cut at least 8 to 12 inches below any sign of infected tissue, into healthy wood, and destroy what you remove. The fire blight bacterium overwinters in cankers and twigs, and those cankers are the source of the ooze that starts next spring's infections. Cutting in the dormant season removes the inoculum when the bacteria are not active and cannot be spread by the cuts themselves.

⚠ Disinfect pruners between cuts with a 10% bleach solution (1 part household bleach to 9 parts water) or 70% alcohol; rinse and oil the tools afterward, since bleach corrodes them. Do not do this pruning during the growing season - cutting then spreads the disease.

Watch for fire blight strikes while the shrub is in flower

During and just after bloom, look for blossoms and shoot tips that suddenly blacken and wilt, with the tip curling into a shepherd's crook. Flag the strikes now and leave them - cut them out during the dormant season. Fire blight bacteria enter through open flowers in warm, wet weather and run down the shoot from there, which is why the damage shows first at the blossom clusters and shoot tips.

⚠ Do not spray any insecticide while flowers are open - flowering quince is one of the earliest nectar sources of the year and is worked heavily by bees. Do not prune the strikes out now either; growing-season cuts spread the bacteria.

Check shoot tips and fruit for cedar-quince rust

In mid to late summer, inspect shoot tips, fruit, and leaves for pinkish tendril-like aecia, and note any swollen, distorted stem cankers. Prune out cankered stems in the dormant season. Do not plant new quince right beside junipers or eastern redcedar. Cedar-quince rust needs both a juniper and a rose-family host to complete its cycle. Spores blow from juniper swellings to the quince during cool, wet spring weather, and the infection only becomes visible on the quince months later, in mid to late summer.

⚠ Fungicides are rarely recommended for cedar-quince rust because none have proven very effective - do not reach for a spray here. Removing nearby junipers may still not control it, since the spores travel long distances.

Expect late frosts to take some of the bloom

This shrub opens its flowers on bare branches very early, ahead of most of the garden, so a late spring frost will brown some of the open blooms. On a small plant you can throw a light cover over it the night a hard frost is forecast; on a large one, accept the loss. The plant itself is hardy well below freezing when dormant, but open flowers are not - and every flower killed by frost is a fruit that will not form, since the bloom comes all at once on old wood.

Pick the fruit in early fall, once it turns from green to yellow

The hard, aromatic pomes ripen in early fall, going from greenish to yellow. Pick them then and cook them - they are far too hard and bitter to eat off the shrub, but they are excellent in preserves and jelly, and the juice works as a lemon substitute. The fruit is a pome that stays rock hard on the bush and never softens to dessert quality; its value is aroma, acidity, and pectin, all of which peak once the skin colors up in early fall.

⚠ The Royal Horticultural Society advises that the seeds contain toxins and should be removed before you eat or cook the fruit (RHS, Chaenomeles speciosa: https://www.rhs.org.uk/plants/3463/chaenomeles-speciosa/details).