Mid-Summer Flower Garden Jobs: Sowing Pansies, Planting Autumn Bulbs, and Greenhouse Potting

Preparing Soil for Outdoor Sowing

Only one group to prep for — plants to be transplanted — so small seed bed in nursery bed, short-term use.

Preparing Soil for Outdoor Planting

Most planting now = autumn-flowering bulbs. Seek naturally medium-to-well-drained, sunny spot. Mix in grit if needed: 3.5 kg/m² (7 lb/yd²). Poor soil? Add little rotted organic matter at 1.5 kg/m² (3 lb/yd²). These bulbs naturally have excellent drainage and summer baking sun — in such conditions, they often self-seed freely.

Preparing Compost for Potting

Work = potting on pricked-out seedlings → J.I. Potting No. 1 type or equivalent.

Sowing Outdoors: Pansies

Excellent time for pansies to flower late spring+ next year. Heavy soil → start of mid-summer best; warm/sandy → end of period. Timing critical: too early = large plants damaged by wind/frost before flowering; too late = too small to establish before winter. Sow thinly in rows 20–25 cm (8–10 in) apart, drill 2.5 cm (1 in) deep, firm cover. Dry soil? Water rows before sowing, gentle thorough sprinkle after. Pansies need well-drained soil.

Planting Outdoors: Autumn Bulbs and Perennials

Colchicum, autumn crocus, Nerine bowdenii in mid-summer. Depth: colchicum 7.5–12.5 cm (3–5 in), autumn crocus 7.5 cm (3 in), nerines shallow — neck just above soil. Crocus and colchicum flower before leaves (late summer/early autumn) — best in sun, dappled shade okay. N. bowdenii (South Africa) needs sun + wall behind bed. Space all a few cm/in apart, leave undisturbed years.

Last month's perennial seedlings → permanent places. Spacing ~2/3 plant height: e.g., 30 cm (12 in) aquilegias → 20 cm (8 in) between.

Transplanting

Late spring-sown biennials for transplanting → move now as advised. Early summer-sown may also be ready if early sowing and good growth. Early mid-summer pansies → transplant at end of mid-summer.

Pricking Out

Early summer greenhouse seed → move to trays: cineraria, calceolaria, Primula malacoides, obconica, sinensis, stellata. Early mid-summer prick-out → may need individual pots by end, especially cinerarias/calceolarias. All to cold frame when pricked out.

Primulas, polyanthus, primroses from early summer → prick out 7.5 cm (3 in) apart each way, still shaded.

Thinning

Late-sown hardy/half-hardy annuals and bedding plants may need final thinning. Early summer biennials → 1–2 thinnings in mid-summer.

Potting

Early summer greenhouse seedlings (Primula malacoides, sinensis, stellata, calceolarias, cinerarias) → first pots late mid-summer. Cinerarias/calceolarias → 7.5 cm (3 in); primulas slow, delicate roots → 5 cm (2 in). Late spring P. malacoides → 7.5 cm (3 in). Cobaea and ipomoea fast → 15 cm (6 in) or final 20 cm (8 in). Late spring cinerarias → 7.5 cm (3 in). With good compost/careful potting, often skip sizes (7.5 cm → 12.5 cm) — saves time/compost. Exceptions: primulas, fussy about drainage.

Permanent pot plants → fresh compost/larger pots if roots at soil-ball edge. Only most vigorous/fast-growing need this now.

Nerine sarniensis (not frost-hardy like N. bowdenii) → pot mid-summer for early autumn flowers. Each bulb: 12.5 cm (5 in) pot, neck just above compost. Cactus compost okay (likes drainage). After planting: good soak, drain, sunny position. Leaves appear during/after flowering.