When to plant tomatoes in Harrisburg: 3 May – 22 July

In Harrisburg, tomato: sow for seedlings from 19 February to 31 May; plant into a greenhouse from 12 April to 22 July; plant out into open ground from 3 May to 22 July. For plants and seeds, the places nearby include The Plant Witch (garden centre, 1 km) and Stauffers of Kissel Hill (garden centre, 13 km); addresses and opening hours are below.

Tomato in Harrisburg: soil, season and weather

In Harrisburg the soil, not frost, sets the date: the last frost is over around 10 April, but the top 7 cm of soil reaches 15 °C — the minimum on the tomato card — only around 3 May, 23 days later.

Last spring frost	10 April
Top 7 cm of soil at 15 °C	3 May, 23 days after the last frost
Into an unheated greenhouse	12 April – 22 July; April outside: 6 °C at night, 17.5 °C by day; card 16–27 °C
First autumn frost	11 November, 192 days after the start
Days in the bed to the first harvest (card)	70
First harvest, if planted in this window	12 July – 30 September
Days left for picking	122
Daylight	11:46 on 12 March, 13:59 on 3 May
Watering outdoors when fruiting (card)	every 3 days; the driest month, November, has 7 rainy days

Tomato in Harrisburg: care after planting

Planted on 3 May: in the first weeks water every 4 days.

Feeding, by the card’s schedule from that day:

3 May — feed: balanced (NPK)
31 May — feed: nitrogen

Pests and diseases of tomato to watch for:

Dates count from the first planting day of the window above; a later planting moves them by as many days.

Weather in Harrisburg during the tomato season

Days average above the tomato card's 16–27 °C in June (27.6 °C), July (31 °C) and August (29 °C). Months that stay below 16 °C even by day on average: November (11.8 °C). Nights average below 16 °C in May and September–November (2.9–15.7 °C).

Month	Day, °C	Night, °C	Rain, mm	Rainy days	Daylight on the 15th
May	22.2	11.4	121	15	14:24
June	27.6	16.5	97	13	15:02
July	31	20.1	126	13	14:47
August	29	19	110	12	13:48
September	25.4	15.7	111	10	12:30
October	19.3	9.7	79	9	11:11
November	11.8	2.9	70	7	9:58

ERA5 2016–2025, Open-Meteo

Tomato in nearby cities

1 of the nearest cities share Harrisburg's date.

City	Distance	Date	Difference
Hagerstown	103 km	28 April – 22 July	5 days earlier
Baltimore	111 km	16 April – 2 August	17 days earlier
Allentown	124 km	3 May – 14 July	same day
Annapolis	148 km	20 April – 30 July	13 days earlier
Philadelphia	150 km	29 April – 22 July	4 days earlier
Washington, D.C.	152 km	15 April – 27 July	18 days earlier

Where to buy tomato plants and seeds near Harrisburg

Buy plants ready to set out from 3 May to 22 July (from 12 April to 22 July for an unheated greenhouse); seed for raising your own is sown from 19 February to 31 May. Within 15 km of Harrisburg OpenStreetMap lists 4 garden centres, 4 markets and 3 farm shops (collected 28 October 2026).

Stauffers of Kissel Hill — garden centre
Gettysburg Pike 51, 17055 Mechanicsburg · 13 km · skh.com
Stauffers of Kissel Hill — garden centre
Middletown Road 1075, 17036 Hummelstown · Mon–Sat 08:00–19:00; Sun 08:00–18:00 · 15 km
Nature's Way Nursery — garden centre
Pleasant Hill Road 1451, 17112 Harrisburg · 13 km · natureswaybonsai.com
The Plant Witch — garden centre
North 3rd Street 11, 17101 Harrisburg · 1 km

Each window starts on the Greenly calendar date and ends on the last day that still leaves the crop’s days to harvest (from its card) before the average first autumn frost, plus six weeks of picking for crops harvested over weeks (tomatoes, peppers, aubergines, cucumbers, courgettes, pumpkins, watermelons, beans) — our rule; earlier in the window is safer.

Questions