Starting broccoli indoors is a great way to get this cruciferous vegetable into your home garden. Some people have difficulties with broccoli plants, but it’s really not too difficult once you know how. Here’s your guide on how to grow broccoli from seed.
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Broccoli is a summer crop and a fall crop. This means that you can plant at two different times to harvest two different times. Alternatively, pick one season and only do one.
There are different varieties of broccoli available. They all have there own pros and cons but my favorite broccoli varieties are:
- Di Cicco
- Waltham 29
- Calabrese – this is what you find in most grocery stores
Starting Broccoli Indoors
When to Start Broccoli Seeds
If you live in a cold climate, starting broccoli indoors will give you the best results.
For a summer harvest, start seeds indoors 4 to 6 weeks before your average last frost date.
For a fall harvest, start seeds 10 to 12 weeks before your average first frost date.
How to Sow Broccoli Seeds
If you desire a faster germination, you can soak seeds in warm water for 12ish hours before sowing. This is an optional step.
Step 1: Fill containers with moistened seed starting mix. For containers, you can use egg cartons, solo cups (drill a hole in the bottom), or store-bought seed starting trays. I like to use a potting soil to start my seeds and have found Baccto to be a great brand year after year!
Step 2: Take a pen or your fingertip and make a small indent where seed will be placed.
Step 3: Place broccoli seed into small hole. If the seeds were purchased this year, plant one per container. However, if using older seeds, plant 2 to 3 per container. Later, thin out the seedlings. Broccoli seeds are very tiny so it is tough to see in this picture exactly where they are. I place two in every square of my container.
Step 4: Cover seed lightly with seed starting mix.
Step 5: Spritz seed starter soil with a spray bottle filled with warm water.
Step 6: Cover containers. Saran wrap or cling wrap is great to use. This mimics a greenhouse.
Step 7: Place in a warm area. On top of a heating pad, on top of the fridge, or in front of a heat source is great. The heat will help the broccoli seeds germinate faster.
Step 8: Once seeds have germinated, place under grow light. The light should be a few inches above the top of the broccoli seedlings. Leave light on for 14-16 hours per day. A timer is a great tool to use so you don’t have to think about turning the light on or off.
Transplanting Broccoli Seedlings
Transplant seedlings when they are 4 to 6 inches tall with at least 2 sets of true leaves. Typically this should be about 2 weeks before your last frost. Make sure to harden seedlings 4-7 days before transplanting.
Place broccoli seedlings in your own garden with full sun (at least 8 hours of direct sunlight per day) and fertile soil. Try not to plant in an area that broccoli or any other brassica had been the year before. Ideally, plant them where you had peas or beans last year. The nitrogen from the peas or beans is great for broccoli!
Space plants 18 to 24 inches apart in rows that are 2 to 3 feet apart.
Keep the garden soil around broccoli transplants watered and covered with mulch.
Harvesting Your Own Broccoli
Once broccoli heads have developed, the best way to harvest is to cut the main head off with a sharp knife. Lave the plant in the ground as smaller heads will sprout up, giving you more to harvest! Go enjoy your fresh broccoli!
- Good companion plants would be beets, onions, and garlic.
- Place compost or organic fertilizer around broccoli plants after transplanting.
- Too much heat can stress out broccoli, so if the temperatures are going to rise about 75 degrees F, try placing a shade cloth over the broccoli heads. Broccoli likes cool weather and the summer heat can ruin them.
- Broccoli plants like well drained soil. It can tolerate slightly alkaline soil, but soil ph is best in the 6.0-7.5 range. You may need to do a soil test to see what kind of soil your own garden bed has.
- Don’t waste the broccoli leaves . Throw them in your compost!
Should you soak broccoli seeds before planting?
Soaking broccoli seeds before planting can speed up the germination process. To do this, just soak seeds in warm water for about 12 hours. This is not required though.
How big should broccoli be before transplanting?
Approximately 4 to 6 weeks after planting broccoli seeds, your young plants should be about 6 inches tall. These plants should also have two sets of leaves. This is the best time to transplant broccoli.
How deep should I plant broccoli seeds?
As a general rule, you want to plant any seed twice as deep as the seed is wide. So, a broccoli seed is tiny, therefore you will only plant it 1/8″-1/4″ deep.
Here are some of the most common problems you may experience from starting broccoli indoors.
Leggy seedlings: This is typically because the plant is not getting enough light. Even if placed in a south facing window or a sunny windowsill, they may not be getting enough hours of sunlight. Add some artificial lighting for indoor growing success.
Seeds not germinating: If seeds are too old they may not germinate. Also, check your soil temperature. Soil should be pretty warm. Between 50 degrees F and 70 degrees F.
Another thing to check is the moisture. Do you have plenty of water? Possibly, you use too much water.
Seedlings won’t grow: You may need to repot the broccoli seedlings into bigger containers. They should not be overcrowded so when you sow seeds, make sure to thin them out once they start growing.