Grow Light for Squash Seedlings: Short Indoor Starts
A grow light for squash seedlings has a short job. Squash grows fast, so the indoor stage lasts only a few weeks. University of Maryland Extension suggests sowing in 3 inch pots about 3 weeks before planting time. Bright light close overhead gives short, sturdy starts.
The short answer
Hang the light 2 to 4 inches above the seedlings plus run it on a timer. Clemson Extension suggests 16 to 18 hours of bright light. University of Minnesota Extension suggests 12 to 16 hours with a dark period each night. Start squash only about 3 weeks before planting out.
How close should the light be?
University of Minnesota Extension advises lights no more than 4 inches above seedlings, with 2 inches as ideal. Clemson Extension suggests a 2 to 4 inch gap, raised as the plants grow. Iowa State University Extension places fluorescent lights no more than 4 to 6 inches above seedlings. A small gap gives a stocky plant.
| Factor | Guide | Source |
|---|---|---|
| Light height | 2 to 4 inches | Clemson Extension |
| Light height | 2 inches ideal, 4 at most | University of Minnesota |
| Light height | 4 to 6 inches at most | Iowa State University |
| Hours per day | 16 to 18 | Clemson Extension |
| Hours per day | 12 to 16 | University of Minnesota |
| Seeding to transplant | 3 to 5 weeks | Clemson Extension |
Source: Clemson Extension, University of Minnesota Extension plus Iowa State University Extension.
How long should the light run?
Clemson Extension notes indoor transplants need 16 to 18 hours of bright light to grow stocky. University of Minnesota Extension suggests 12 to 16 hours. It advises against leaving lights on all the time, since many plants need a dark period each night. Iowa State University Extension suggests 12 to 14 hours.
Why start squash so late?
Squash needs warm weather to grow. University of Maryland Extension advises planting after the danger of frost has passed. Clemson Extension lists 3 to 5 weeks from seeding to transplant for squash. University of Minnesota Extension suggests fiber or paper pots for crops that do not transplant well, such as squash.
How to: step by step
- Count back roughly 3 weeks from your planting date.
- Sow into 3 inch fiber or paper pots.
- Suspend the light 2 to 4 inches over the pots.
- Set a timer for 12 to 16 hours.
- Lift the light as the seedlings grow.
- Plant out once frost danger has passed.
Troubleshooting
Tall, floppy seedlings: too little light. Lower the light to 2 to 4 inches.
Roots disturbed at planting: squash dislikes transplanting. Use pots that break down in the soil.
Starts too big for the pot: sown too early. Sow about 3 weeks before planting out.
For related reading see cannabis seedling light schedule, leggy cannabis seedlings plus potting up cannabis seedlings. Kind Seed Co also stocks cannabis seeds.
Sources
- Growing summer squash and zucchini in the home garden, University of Maryland Extension
- Starting seeds indoors, University of Minnesota Extension
- Starting seeds indoors, Clemson Extension
- Will a fluorescent light fixture provide sufficient light for seedlings, Iowa State University Extension
FAQ
When should squash seeds be started indoors?
University of Maryland Extension suggests sowing in 3 inch pots about 3 weeks before planting time. Clemson Extension lists 3 to 5 weeks from seeding to transplant for squash. Count back from the date when frost danger has passed, so the starts do not outgrow their pots before they go out.
How far should the light be from squash seedlings?
University of Minnesota Extension advises no more than 4 inches, with 2 inches as ideal. Clemson Extension suggests a 2 to 4 inch gap that you raise as the plants grow. Iowa State University Extension allows up to 4 to 6 inches for fluorescent lights. A close light gives stockier plants.
How many hours of light do squash seedlings need?
Clemson Extension suggests 16 to 18 hours of bright light. University of Minnesota Extension suggests 12 to 16 hours and advises a dark period each night. Iowa State University Extension suggests 12 to 14 hours. A simple timer turns the lights on and off at the same times every day.
What pots work for squash starts?
University of Minnesota Extension notes fiber or paper pots that break down in the soil suit crops that do not transplant well, such as squash. University of Maryland Extension suggests 3 inch pots and advises handling transplants gently. Disturb the roots as little as possible when the plants go into the garden.
Can squash be sown straight into the garden?
Yes. University of Maryland Extension notes squash can be sown directly after frost danger has passed and the soil has warmed. Starting indoors under lights simply gives a jump on the season. Either way, squash needs warm weather, since frost injures the top growth of the plant.
