The most notable thing to know about growing broccoli is that it tastes best if it matures in cool weather. Even though broccoli can be planted in both the early spring and late summer, your fall harvest will usually provide a healthier, better tasting broccoli.
How to Grow Broccoli - The Basics
Soil that is rich in nitrogen is best for planting broccoli. Rake in a ~3 inch layer of aged compost/manure approximately two weeks before you plan to transplant your broccoli seedlings outdoors. When planting broccoli, ensure that you DO NOT choose a planting location that previously grew plants from the same family(brassica) as broccoli (ie. cabbage, cauliflower, brussel sprouts).
This will greatly aid in the prevention of soil-borne diseases that affect this family of vegtables. Additionally, broccoli will grow best in a soil that is slightly acidic (pH of ~6-7).
Watering and Sunshine
One of the most important things to know aout learning how to grow broccoli, is that broccoli requires a lot of water and sunshine. Ideally, choose a location where the plants will get approximately 8 hours of sunshine per day, and provide broccoli with continuous watering, especially if the soil become dry. Deep, slow waterings are recommended using a soaker hose or drop irrigation.
A thick, loose layer of mulch placed around the growing brocolli will aid in moisture retention. Overhead watering is not recommended, as it can lead to disease, especially if the plants are maturing.
Fertilizing and Weeding Broccoli
Once the growing broccoli plants begin to produce heads, pull back the mulch and mix in a nitrogen-rich compost/manure, with the soil around the plants. Be careful not to mix in too deep. If you need to weed, carefully pull the weeds by hand, otherwise hoeing can damage the plant roots.
How and When to Plant Broccoli
Growing broccoli in Spring is best done by growing seeds indoors, and then transplanting the seedlings outdoors. This allows a jump on the growing season, which will lead to harvesting earlier while the weather is still cool (Better tasting broccoli!). Be aware that quickly increasing temperatures in spring can encourage broccoli to flower prematurely, or make the heads taste bitter.
Here are the steps for indoor planting:
- Sow your seeds 6-8 weeks before the last expected frost in your area.
- Plant 3-4 seeds in a flat or pot, about 1/4 to 1/2 an inch deep in a compost-rich soil. Water well, but do not saturate the soil.
- Keep the flat in a dark, cool place. Thin out the weakest seedlings until you have one plant per compartment.
- When the broccoli seedlings are 1-2" tall, transplant to individual pots. Plant them to a depth that is just below the leaves.
- Give the seedlings lots of sunshine, as long as they remain cool. It is very important that they remain cool.
- Once the seedlings are 4-6 inches tall, they can be hardened off and transplanted, as long as you are within 2 weeks of the last frost. (Please visit our Growing Vegetables page for the hardening off and transplanting definition/guidelines).
- When you transplant, place the seedlings 18-24 inches apart, and keep the rows about 3 feet apart. Plant the seedlings to a depth just below the first set of leaves.
For a Fall harvest, plan to plant seeds 12-14 weeks before the average first frost. Sow the seeds about 1/2 an inch deep and 1-2 inches apart. As they grow, thin out the weaker broccoli plants until you have broccoli plants that are spaced about 18-24 inches apart.
If you wish, an alternative is to grow seedlings as you did in spring - just follow the how to grow broccoli "spring" instructions as set out above. As the weather cools you will have broccoli maturing that is sweet and tender!
Cool Weather is Best
As mentioned above, the best time for harvesting broccoli is in cool weather. Try to harvest the heads in the morning, before the heat of the day which will help the harvested broccoli to stay firm and sweet longer.
The Broccoli Head Should Be Firm and Tender
Most varieties of broccoli mature within 60-85 days once planted outdoors. Growing broccoli will first produce a thick stem with large leaves. Slowly, a small head will begin to emerge. Monitor the broccoli head continuously and harvest if it starts to turn yellow or begins to loosen (The individual buds will soon flower once the head loosens).
Cut the Stalk at a Slant
Harvesting broccoli is best accomplished by cutting the stalk at a slant (this prevents pooling water which will rot the plant) about 4-7 inches below the head. This method of harvesting broccoli will encourage side-growth, where small heads will grow from the sides of the stalk.
The broccoli plant may produce side-growth for up to 5 or 6 weeks. Once production of the broccoli heads stops, dig out the broccoli plant, and compost.
What Can Go Wrong When Growing Broccoli
There are three main things that can you wrong when growing broccoli. When learning how to grow broccoli, please note that broccoli plants will commonly face:
- Nitrogen Deficiency
Broccoli commonly is attacked by caterpillars, slugs, snails, or maggots. The best defense against these is to install a collar around the stalk of the plant and cover the plant securely with a crop protection mesh. If you find a small infestation, pick of the pests off individually, usually from the underside of the leaves. If they persist, see your local garden store for an appropriate pesticide.
Growing broccoli requires a nitrogen-rich soil. Plants suffering from nitrogen deficiency will begin to turn yellow, and will eventually die. To prevent this, ensure that you prepare the soil (before planting) by mixing it with a fertilizer that is high in nitrogen. If you see any symptoms of nitrogen deficiency, scratch more of the fertilizer into the soil around the plants throughout the season. Please note the over-watering can also lead to a yellowing plant as well.
The most common disease of broccoli is clubroot. Clubroot is indicated by a yellowing, weak plant with malformed roots. This fungal disease is best prevented by crop rotation and a soil with a pH slightly higher (just above 7) than recommended for broccoli. Crop rotation means that you grow broccoli in a location where no other member of the brassica family has been grown for ~3 years.
Growing Broccoli - Conclusion
We wish you the best and hope that you have learned all that you need to know about how to grow broccoli. If you already grow great broccoli, please contact us. We'll add your valuable advice to this page, and name you as contributor(if you wish!).