I have been encouraging purslane in my garden for several years. It's growing now among my pole beans. Wikipedia notes that it grows in compacted soils. I have a large patch growing in a thin gravel pathway over compacted clay. In fact, that's where I noted the first plant. Its growth habit there is considerably different than the plants growing in my well-composted garden soil. It's sad that it got stuck with the nickname, "pigweed".