Growing tarweed from seed

Annuals are not generally thought of as landscaping plants. The conventional approach to landscaping, even native landscaping, is to use perennials sparsely placed among a mulch matrix. This is convenient for landscaping companies, since the process is relatively simple (cover weeds with plastic, cover plastic with mulch, add occasional plants).

But annuals have a lot to offer, too. They produce immense amounts of biomass, which of course is the foundation of life: this plant biomass turns into insect biomass, which turns into bird biomass, and so on. Plants are the foundation of ecosystems, and biomass is the building block.

Annuals can be established in massive quantities at low costs when planted by seed. This makes sense, since plants ready for transplant cost about $5-10, while seeds are in the small cents or fraction of a cent. Some care is needed to establish the seeds, but if implemented properly you can produce immense amounts of plants for cheap, whether you want DIY transplants or a thick meadow of wildflowers (as a lawn replacement or a beneficial insectary).

Tarweed, despite its lackluster name, can be a great (as well as cost-effective) addition to your native garden. It provides habitat and food for many specially adapted beneficial insects, and can be a valuable part of your pest-control strategy.

Some seeds are very easy to establish. Poppy and lupine are some of the easiest natives, and since they germinate quickly they can outcompete some weeds when sewn at the right time. Others, like tarweed, are a bit trickier. Still, with the right timing and soil preparation, anyone can get them to grow.

One of the largest benefits of establishing native plants from seed is that they actually require no water. None. Not even drip. It can take a few seasons of re-seeding to establish a native seed bank that can outcompete common urban weeds, but once this seed bank establishes, the annuals are there to stay.

How to grow tarweed from seed

Tarweed seeds (Madia elegans).

Tarweed seeds (Madia elegans).

There are two basic ways to do this: seed directly in the soil, or germinate indoors then transplant the seedlings. Both are simple but must be done properly. From here on out I am going to focus on a species of tarweed dear to my heart, Madia elegans, called common madia and showy madia – but I’ll just refer to it as tarweed for the sake of simplicity. Besides, getting seeds from the other tarweed species to establish is virtually the same (for the record, the tarweeds are fascinating as a taxonomic group in their immense adaptability: they are the ancestors of the Hawaiians silverswords, which look nothing like them and exist in the wettest and driest parts of the world).

If you want to establish tarweed directly from seed (this is what I would recommend in general), keep in mind that it’s more of a disturbance colonizer than a great competitor. If there are other plants growing where you sew the seeds, your chances aren’t great. So remove everything else first, and don’t mix in other seeds where you want to establish tarweed. Or sew the seeds in gravel, sides of paths or in cracks in pavers or cement - they will thrive there will out any preparation.

Increase the drainage of the soil too.  I like to mix in 1 part sand to 3 parts soil, plus about 1 part gravel. Tarweed will do incredibly well in cracks in cement, gravel, places you walk a lot, patios, etc, but has a harder time sometimes in dirt that looks more friendly. So prep it first.

Or just let your dog dig in the soil right after sewing the seeds.

Once the seeds germinate, you should get pretty decent survival – the tough part is getting them to go from seed to seedling in the soil. Snails will eat the young plants, but stop once they become sticky.

A great place to put tarweed is on the perimeter of your vegetable garden. The small insects that get stuck in tarweed’s sticky secretions feed a variety of beneficial insects which will build up on these native plants then move into your garden to suppress pests. Establishing a border of native plants like tarweed (that support native predators) will give you permanent, self-sustaining pest control. No more aphid outbreaks.

Tarweed provides protein-rich food (in the form of dead insects stuck to its sticky hairs) for beneficial insects, providing effective and natural pest control.

Tarweed provides protein-rich food (in the form of dead insects stuck to its sticky hairs) for beneficial insects, providing effective and natural pest control.

If you’d rather grow tarweeds one by one, there’s a way to do that, too. Take the seeds and wrap them in a wet paper towel. I usually soak a paper towel, wring it out, then put seeds in it. Put the paper towel in a plastic bag and put it all in the fridge. After a few weeks the seeds will germinate. Then, place them one-by-one by hand into small pots with a mixture of 1 part sand to 3 parts potting soil. It’s best to water from below – if possible, put the pots on a tray where you can soak them in an inch or so of water until it’s absorbed by the soil. Don’t overwater. You want the soil to be moist but not wet. Let the very top layer of soil be dry or moist, but water more if the plants wilt. If the leaf tips become pale, water less (this strategy can be applied to any plant).

Keep the sprouts in the shade until they put on a few true leaves, Once the seedlings put on a dozen or so leaves, and the roots reach all corners of the pots, they’re ready to transplant into the soil like any plant. They will need water at first, and you might lose some leaves (but that’s fine).

Tarweed seedlings with 2-4 true leaves

Tarweed seedlings with 2-4 true leaves

Tarweed has been valued by wildlife for millions of years. It was a staple to the Pomo Indians, who ate its seeds for protein. Tarweeds are immensely drought-tolerant, beautiful, smell lovely, provide natural, chemical-free pest control, feed birds, protect pollinators, and much more. And yet, thanks to an unfortunate name, they get no respect. Restoration Landscaping Co. intends to change that. Get in touch to find out more!