Mid-Spring Flower Garden Jobs: Lawn Seeding, Sowing Annuals, and Greenhouse Propagation

Preparing Soil for Outdoor Seed Sowing

Big spring job: lawn from seed. Soil dug autumn/early winter, most weeds removed. Now: final cleanup ~week before sowing — fork top few cm to remove weeds/rubbish, break large lumps. Add ~7:7:7 compound fertilizer when forking. Week later, sowing day: rake for fine surface, rough level, then finished level with line, pegs, boards, spirit level. No bumps/hollows → tread to consolidate lightly, final rake on boards for right tilth.

Flower seed beds → same as early spring.

Preparing Compost for Seed Under Glass

If not done late winter/early spring → mix ASAP for blending time.

Preparing Soil for Outdoor Planting

Much same as early spring + additions → follow early spring instructions, fertilizer a few days before planting.

Preparing Compost for Potting Under Glass

Potting composts → early mid-spring, leave in greenhouse to warm to plant temperature.

Sowing Seed Outdoors

Grass seed → early mid-spring. Germinates 7–10 days, another 10–14 before first cut. Windless day. Mark area in m²/yd² with lines → even sowing.

Rate: 45–60 g/m² (1½ oz/yd²), higher if birds problematic or germination tricky. Hand-sowing evenness: half seed one direction, half at right angles. Important — patchy start = never even sward. Large areas → fertilizer distributor with metering roller. Two half-sowings advisable.

After sowing: light rake + cross-rake best, but dispensable if short on time. Bird inhibitors on, or black cotton above soil on small areas. Bird-treated seed → loses viability fast, use same season only.

Hardy annuals → this month, better display chance. Early spring germination risky (treacherous weather). Add to early spring list: aster, dahlia, layia (tidy tips), nasturtium, nicotiana, salpiglossis, sweet sultan, ursinia, xeranthemum (everlasting), zinnia. Sweet peas not quite too late but flower late summer.

Nursery bed (indispensable for flower/veg) → sow bulbs (crocus, lilies, snowdrops), herbaceous perennials, rock plants. Cloche protection if freezing nights. Sow thinly, especially bulbs.

Sowing Seed Under Glass

Greenhouse: same half-hardy annuals/bedding as last month but unless very cold, no artificial heat by day. Cobaea, ipomoea, freesia for autumn/early winter flowers. Cobaea/ipomoea = large seeds, fast growth → sow singly in 5 cm (2 in) pots, preferably peat pots, easier first potting.

Ipomoea especially hates root disturbance → first 2–3 true leaves yellow then white, growth stops, plant dies. Yellowing also from bright sun or temp <16°C (60°F). Needs warm compost and air — nearer 21°C (70°F) better.

Freesias from seed easy. Sown now at 16°C (60°F) → first flowers mid-autumn. Unusually long taproot → deeper container better, ≥17.5 cm (7 in). J.I. Potting No. 3 (soil-based). Seeds 2.5 cm (1 in) apart and deep. 23 cm (9 in) pot → 9–10 seeds. Long straggly leaves/stems → 37.5 cm (15 in) split canes with string across for support, around edge and center → plants grow through network. After germination, lower temp slightly.

Planting Outdoors

As early spring: plant/lift/divide herbaceous plants, but early as possible — growth really starting.

Best time for rock garden plants — preferably just after flowering, but movable in flower if quick, minimal root damage, water in, never want for water establishing. Cool, moist conditions best.

Violets → now, bought or own crowns (pieces with plenty roots). Thrive: protected from midday summer sun, moist humus-rich soil. Water in unless rain imminent. Violet midge signs → pick affected leaves.

Gladioli → mid-spring, weekly intervals for succession. Allium, crinum, montbretia → season start. Alliums: sunny, gritty soil → some species naturalize to nuisance.

Crinum x powellii → deep pink lily-like flowers late summer/autumn. Large bulbs 15 cm (6 in) deep, 23 cm (9 in) apart. Well-drained soil + plenty winter rotted organic matter, sunny at south/west wall foot. Once planted → leave years if spring-mulched. With agapanthus (blue African lily, same conditions) → very pretty color combo.

Thinning

Early spring outdoor sowings → thin next few weeks. Thin = remove some seedlings for remainder space to mature. When just handleable → ~5 cm (2 in) between. Second thin at 5–6 true leaves → 10–20 cm (4–8 in) by final height.

Wild white daisy bred/selected → double rose-pink flowers from seed strains.