Early Autumn Flower Garden Jobs: Soil Prep, Sowing, Planting, and Propagation

Preparing Soil for Outdoor Seed Sowing

Soil in beds, borders, nursery bed, and lawn site should be ready for sowing. Deep digging and levelling done in late summer — now just finishing touches early in autumn.

Preparing Soil for Outdoor Planting

Most plants going in now are small; also bulb-planting time. Small plants establish better in crumbly, moist (not soggy) soil with phosphatic fertilizer (e.g., bonemeal) worked in two weeks ahead at 90 g/m² (3 oz/yd²). Bulbs like good drainage but tolerate reasonable soil with same dressing. Lilies are fussier — need grit or coarse silver sand mixed in for average-to-heavy soils. Single digging suffices.

Can also start preparing beds/borders for first-time herbaceous perennials — bigger job since they stay years. Many are deep-rooted; double digging advisable with rotted organic matter. If topsoil is shallow, one spit is all you can manage — be especially careful to mix compost/manure into trench bottom as well as topsoil.

Preparing Compost for Sowing and Potting Under Glass

Less work here to balance outdoor increase — some sowing, potting, pricking out. You may have enough compost made or bought.

Sowing Seed Outdoors

Sweet peas for early summer flowering: sow now. If planted in greenhouse soil in mid-winter with frost protection, they flower late spring. Overwinter in pots — J.I. Potting No. 1 or equivalent suffices. Sweet peas grow long tap roots — use long, narrow disposable plastic cups (heat drainage hole in base). Sow one seed per 5 cm (2 in) pot, covered to own depth. Nick slow-germinating seeds with knife. Pots in closed cold frame; germination ~10 days. Protect from mice. After germination, remove frame light but guard against sparrows nipping tips.

Best sowing time: mid early autumn for cold gardens; late early autumn or early mid-autumn for sheltered/warmer ones.

Hardy annuals for late spring+ flowering: sow in flowering positions in first two weeks. Choices: annual chrysanthemum, clarkia, cornflower, eschscholzia, godetia, larkspur, limnanthes, marigold (calendula), nigella (love-in-a-mist), viscaria. All very hardy — if sown early enough, they'll be robust enough for winter.

Grass seed for new lawns can be sown.

Planting Outdoors: Bulbs and Lilies

Autumn = prime time for spring-flowering bulbs — plant early as possible. Use early-autumn planting list from Late Summer bulb table. None love organic matter, but bonemeal or hoof-and-horn give a good start, mixed in 10 days before at 90 g/m² (3 oz/yd²).

Lilies (except Lilium candidum) can go in early or mid-autumn with same soil prep. Exception: L. davidii needs leafmould for best flowers. Stem-rooting types (L. auratum, bulbiferum, croceum, davidii, formosanum, longiflorum, regale, speciosum, tigrinum) plant 15 cm (6 in) deep. Acid-soil lilies: auratum, formosanum, longiflorum, speciosum, tigrinum. L. candidum needs a little lime. L. martagon (purple turkscap) and L. pardalinum (leopard lily) at 10 cm (4 in). All with silver sand beneath bulb for perfect drainage.

Transplanting

Pansy seedlings from late summer nursery bed → permanent positions (bed, window box, trough). Lift with trowel, plenty of soil for intact roots; replant slightly deeper, firm well, water. Spacing: 22.5–30 cm (9–12 in) outdoors (wider in heavy soil), 15 cm (6 in) in containers.

Primulas and polyanthus from early summer seed → flowering positions, 15–23 cm (6–9 in) apart each way.

Border carnations not direct-planted → transplant from pots to sunny flowering position.

Pricking Out

Late summer-sown schizanthus → prick out ASAP to prevent legginess. Space 5 cm (2 in) in seed boxes. Cyclamen with two leaves and tiny tuber → move at 4 cm (1½ in) apart. Keep warm, especially nights as autumn cools.