Mulch is critical to broccoli since it prefers cool soil. Organic mulch cools the soil 4 to 6 degrees. Spread a 2 to 4 inch layer of chopped leaves, hay or straw over the soil around and between the broccoli plants as soon as their stems are high enough so there is space for the mulch. Do this after removing any frost protective shelters you may have used.
For more information see file on Using Mulch In The Vegetable Garden.
Do not allow broccoli plants to dry out, because the stems get tough and stringy in dry weather. Technically, broccoli needs about 1 to 1 1/2 inches of water or rain a week. However, broccoli that is well mulched and is growing in soil with lots of organic material that holds water, can go 10 days or more between waterings. Porous hose irrigation systems hooked up to mechanical or computer watering timers are very effective for reliably delivering water in the vegetable garden. For more information see Watering The Vegetable Garden
Broccoli needs the most nutrition during the first half of its life. Mixing slow-acting granular fertilizer into the soil when you prepare the planting area will provide continuous and consistent nutrition over many weeks. If you mulch your broccoli and/or the soil contains lots of organic matter, this should be sufficient until harvest time.
If your garden soil is poor and thin, and you are not mulching your plants with an organic material that will decompose and provide organic matter to improve it, then consider feeding the plants with liquid fertilizer about three weeks after planting. Use a very dilute solution as a spray on their leaves or watered into the soil near their roots. Repeat the dose when the broccoli head has formed and grown to a few inches across. This will probably be about ten days before harvest. This second feeding stimulates plants to produce edible shoots for several weeks afterward.
Broccoli responds to plant growing tonics which contain kelp or other seaweed byproducts and help the broccoli deal with stress more effectively. A single dose of one of these products in late spring can improve head size and flavor.
For more information see Fertilizing the Vegetable Garden
Plant Health Insurance – For Better Production
There are several relatively new organic products available that when applied to broccolli plants as a foliar spray, the disease resistance of the plant increases considerably and the plant’s ability to resist pest insects also goes way up. In addition these products help insure the best health of the plant which leads to the largest fruit with the highest nutrition possible at harvest.
Two products serve this benefit –They are Vegetable Thrive and Liquid Kelp. You get the results if you foliar feed these two products on all the leaves of the broccoli plants once a month until harvest is completed.
Protecting the Broccoli Crop
Shading: If temperatures reach the 80’s before you harvest all your broccoli, spread shade cloth over the broccoli plants to keep them a bit cooler and encourage more side shoots. See Yardener’s Tool Shed for information about buying shade cloth. Go to the Products to Protect Plants section or type “shade cloth” into the search function on the left.
Rotating: Never plant broccoli in the same place in the garden two years in a row. In fact try to rotate all Brassica crops, so that no cabbage, broccoli, or cauliflower are grown in the same place two years in succession. If possible plant broccoli in a different area for 4 years before returning to a previous planting site. Moving even just a few feet is better than no rotation at all. This way disease and pest organisms that lie in wait in the soil from a previous year are disappointed when there is no broccoli there in the new season.