Are there any common allelopathic plants suitable as a pre-lawn winter cover crop?

Question

Being March in the Southern hemisphere, winter is approaching. I have just had my very-weedy front yard levelled. Most of the weeds have been removed, but I don't want to sow grass until I've given some of the remaining weed stalks a chance to show themselves so I can dig them out.

I'm thinking about sowing lupins to cover the ground in the meantime. I think lupins would have the added advantage of growing relative quickly (as the seeds are large).

Are there any alternative winter cover crops that have allelopathic properties (so would prevent or slow growth of at least some of the weeds).

I'm in New Zealand, with a moderate climate. Temperatures will range roughly between -5 (overnight) and 15 C over the winter.

Answer 1

Winter rye is allelopathic, inexpensive, and very hardy. I don't know about suitability as "pre lawn". It can be challenging to kill in the spring when you're ready to plant. I rototill it once or twice, then wait a couple of weeks before trying to plant any seeds.

I'm not sure about sowing lupins -- it wouldn't work well for me because we'd be hitting -5°C and down to -20°C in midwinter, but perhaps in your climate they will grow enough in the fall. They have the added advantage of fixing nitrogen and being relatively easy to kill in the spring.