5 Plant Families Sabotaging Your Garden
Every home gardener cherishes the satisfaction of nurturing vibrant, healthy plants. But while you might be diligently watering and fertilizing your crops, there could be unseen saboteurs lurking among your vegetables: weeds. Not just any weeds, but those that look deceivingly similar to the crops you care for—and that can carry devastating diseases and pests.
These weeds, often in the same families as our crops, act as alternate hosts for viruses, fungi, and pests that can spread rapidly through your garden. Let’s look at the five plant families most likely to cause issues, along with expert tips on identifying and removing them.
1. Brassicaceae (Mustard Family)
This family includes garden staples like broccoli, cauliflower, kale, and radishes. Unfortunately, it also includes weeds like wild mustard, shepherd's purse, and wild radish, which can attract cabbage aphids and whiteflies. These pests don't just feast on the weeds—they carry over 20 plant viruses, including Turnip Mosaic Virus, which can wreak havoc on your crops.
How to Identify: Brassica flowers have four petals in a cross shape and six stamens (four tall, two short). Look for yellow or white blooms, green leaves with a mustardy smell, and seed pods known as silique.
What to Do: Remove these weeds as soon as they flower. Consider using insect netting to protect your crops from pest migration.
2. Solanaceae (Nightshade Family)
Weeds like deadly nightshade and jimsonweed (datura) are part of the same family as tomatoes, eggplant, and peppers. These weeds can carry Tobacco Mosaic Virus, Tomato Yellow Leaf Curl Virus, and other destructive diseases. Even worse, they serve as homes for pests like aphids, whiteflies, and hornworms.
How to Identify: Five fused petals forming a star or tubular shape. Flowers are usually purple, white, or yellow. The fruit is often a berry or capsule.
What to Do: Remove roots and all, wearing gloves as many nightshades are toxic. Be vigilant in early spring, as these weeds can overwinter and reintroduce diseases each season.
3. Asteraceae (Daisy Family)
This floral family includes daisies, dandelions, and thistles. While they may look pretty, they often host pests like leaf miners and flea beetles, and can carry rust fungi. These pathogens spread easily through wind and insect movement.
How to Identify: Composite flower heads made up of many tiny flowers. Leaves are usually lobed or rough.
What to Do: Remove them before they go to seed. Thistles, in particular, are often classified as noxious weeds and must be legally removed in some areas.
4. Polygonaceae (Knotweed/Buckwheat Family)
This family includes knotweed, which is notorious for its aggressive spread. Japanese knotweed can take over a garden quickly and host root pathogens that compromise plant health.
How to Identify: Hollow stems with swollen nodes (like joints), small greenish-white clustered flowers, and a sheath (ocrea) around leaf stems.
What to Do: Dig deep and remove all root fragments. Any remaining roots can regrow. Monitor the area throughout the season.
5. Amaranthaceae (Amaranth Family)
Pigweed and lamb's quarters are the usual suspects here. These weeds can transmit leaf spot and mosaic viruses to spinach, beets, and chard. They also spread rapidly due to their dense flower spikes and tiny wind-blown seeds.
How to Identify: Dense reddish or green flower spikes, simple alternate leaves, and slightly fleshy stems.
What to Do: Pull before flowering or cover infested areas with tarps to block sunlight. Avoid composting infected plants.
Prevention Tips
Identify by Flower Structure: The most reliable identification method is by flower shape.
Early Removal: Pull weeds before flowering to prevent seed spread.
Protect and Sanitize: Use insect netting, clean tools, and avoid transferring disease from weeds to crops.
Monitor Edges and Debris: Many weeds overwinter in garden edges. Regularly clear out debris.
Your garden’s health sometimes begins with what you remove, not just what you plant.
Listen to the full podcast episode for a practical guide on what to pull, when, and why: https://justgrowsomethingpodcast.com/episode/know-thy-weeds-5-plant-families-sabotaging-your-garden-ep-255
Your Friend in the Garden,
