Butterfly Weed

Butterfly weed is the plant that monarch butterflies depend on to complete their lifecycle, and that ecological fact is the main reason gardeners plant it. But it also happens to be genuinely beautiful — the orange flower clusters bloom from midsummer through fall, and the plant asks for almost nothing once it settles in. The difficulty is that settling in takes longer than most gardeners expect, and the plant's habits can alarm someone who doesn't know what to watch for.

The deep taproot is both the plant's greatest strength and its main difficulty for the gardener. Once established, butterfly weed can survive droughts that kill most garden perennials, and it will live for decades without any care. But that same taproot means the plant emerges late in spring — often not until mid-May or early June, weeks after everything else is up — and it is nearly impossible to transplant successfully after the first year. Mark the spot where you plant it, because in April it will look like bare ground, and more than one gardener has accidentally dug it up while putting in something else.

If you're starting from seed, sow in fall or stratify the seeds in the refrigerator for a month before sowing in spring. The seeds need a cold period to germinate reliably. Transplants from a nursery can go in at your last frost date, but handle the roots carefully — if you break the taproot, the plant may survive but will struggle for a season or more. Plant in the spot where you want it to stay, because moving it later tends to kill it.

Soil drainage matters more than fertility. Butterfly weed is native to dry meadows and roadsides, and it rots in heavy, wet clay. If your garden soil holds water, plant it on a slope, in a raised bed, or in a spot where you've worked in coarse sand or gravel. It doesn't need rich soil and doesn't benefit from fertilizer — in fact, too much nitrogen tends to produce lush foliage at the expense of flowers.

Monarchs will find the plant without any help from you. The caterpillars are large, boldly striped in yellow, black, and white, and they can strip a plant nearly bare in a few days. This is not a failure — it's the reason you planted it. The plant will regrow from the base after the caterpillars pupate, and if you planted more than one, they'll recover in rotation. Aphids, particularly bright orange oleander aphids, are also common on milkweeds; a sharp spray of water usually dislodges them, but the monarchs don't seem to mind them.

Deadheading spent flowers can sometimes encourage a second flush of bloom later in the season, but many gardeners leave the seed pods to ripen — they split open in fall, releasing seeds with silky white parachutes that scatter on the wind. If you want to control where the next generation grows, collect the pods before they open.