Broadleaf weeds compete with spinach in the field and make machine-harvesting next to impossible. Whether you grow spinach for the fresh or processed/frozen market, you’ll need to address the issue of broadleaf weeds as part of your spinach plant care plan. Here, we’ll describe the kinds of weeds to look out for and some strategies for keeping your spinach weed-free.
Which Broadleaf Weeds Are a Problem?
The kinds of weeds that compete with spinach vary by region, even within the state of California. Weed patterns are also affected by the time of year the spinach is grown (all year round or a fall/winter growing season). However, there are a few species that are clearly identified as problematic:
- Burning nettles
- Little mallow/cheeseweed
- London rocket
- Shepherd’s purse
How Broadleaf Weeds Affect Spinach Crops
Aside from the obvious problems of competing for space and creating a contaminated weed-and-spinach harvest, weeds can also introduce other problems into your crops such as pathogens, nematodes, vertebrates, and insects. These pests can migrate onto emerging spinach seedlings and cause significant amounts of damage.
Integrated Spinach Plant Care
Unfortunately, managing broadleaf weeds isn’t a straightforward process. The traditional approach of weeding spinach beds by hand is labor-intensive and isn’t always possible in densely planted stands. Generally, growers use a combination of pre-plant, preemergent, and post-emergent techniques to keep the field free of weeds and allow the spinach to flourish.
Before planting spinach, it’s essential to look at the ground that you’ll be planting into and whether it’s suitable for a healthy, weed-free crop. Consider the following before planting your seeds:
- Choose a field with low weed pressure.
- Follow the recommended plant back intervals if chemicals have been used on the field.
- Consider rotating spinach with crops like lettuce, tomato, beans, and sweet corn.
- Be aware of chemicals that were used on vegetables grown in previous rotations.
Once you’ve selected the perfect field, there are several strategies you can use for discouraging broadleaf weeds before they become established:
- Sanitize all field equipment to avoid introducing weed seeds into the field.
- Prepare the seedbed with a level top to allow for rapid and uniform precision planting.
- Solarize the soil over summer in CA’s interior valleys if the field is left fallow.
- Preirrigate once or twice before preparing the seedbeds. Cultivate, flame, and apply herbicides if desired.
- The most common kinds of herbicides for pre-plant treatment include fumigants, foliar herbicides, and incorporated herbicides. Be sure to check which weeds they kill and follow instructions regarding use and waiting periods before planting spinach.
Healthy, well-fertilized, weed-free soil should give your seeds and/or seedlings the best chance to thrive. However, it’s likely that you’ll still see broadleaf weeds appear in the beds both before and after your seedlings emerge. The way that you’ll go about spinach plant care depends on how your beds are planted, the kinds of weeds you have in your beds and your budget for mechanical techniques like hand-weeding.
- Uniformly planted spinach stands leave fewer gaps for weeds to emerge.
- Beds with two lines of seeds can be cultivated to 2 inches in depth to dislodge weed seedlings as they emerge.
- Weeds can be removed by hand. This is the slowest and most expensive approach.
- Preemergent herbicides like Cycloate (Ro-Neet) and S-metolachlor (Dual Magnum) can be applied between planting and the first irrigation. Follow with 0.5-0.75 of water.
- Post-emergent herbicides like Phenmedipham (Spin-Aid) can be used at the 4-6 true leaf stage. This herbicide is only suitable for use if the spinach is being grown for seed or processing — not for spinach destined for direct consumption.
If you are an organic grower, spinach plant care is likely to look a bit different than it would in a conventional field. You still need to deal with broadleaf weeds to stop them from taking over your crop. However, you’ll have fewer (or different) tools to achieve this.
As with conventional spinach, focus on strategies like crop rotation and preparing fertile beds for your seeds with mature compost that’s easily leveled (and not clumpy). You can also use soil solarization for a period of 4 to 6 weeks in the summer to kill the seeds of annual weeks if the land is fallow and you are happy to use clear polyethylene (PE) plastic.
After planting out your seeds or seedlings, surface cultivation can be used to pull up the seedlings of broadleaf weeds as they appear. Aside from that, you’re basically looking at hand weeding until the harvest.
In order to keep the weeds to a minimum, organic growers have experimented with planting living mulches like subterranean clover (Trifolium subterraneum L.) soon after the spinach. In this experiment, the clover was seeded several weeks after the spinach, along with a “sequence of diverse direct physical weed control operations.”
Compared with spinach and a regular biodegradable mulch, this strategy led to a higher yield (+26%) and continued protection from weeds in the beds even after the spinach had been harvested for sale. However, this technique is quite labor-intensive as it still requires harvesting the spinach by hand.
Beat the Broadleaf Weeds with Fruit Growers Supply
Spinach plant care is essential for a healthy harvest, and Fruit Growers Supply is here to help. In our full-service retail stores, located in Orange Cove, Woodlake, Riverside, Porterville, and Santa Paula, we sell an extensive range of herbicides for vegetable crops as well as tools for hand weeding and mechanized weeding.
If you have any questions about dealing with broadleaf weeds and other pests that affect spinach, don’t hesitate to contact our team at 866-477-7414 or write to us online.