One More Harvest Before Autumn: Sow Radishes and Mizuna Now
Late August is far from the end of the season. Radishes need about four weeks, mizuna a good five - which means fresh greens in your raised bed well into October.
The zucchini is done, the bush beans are turning yellow, and suddenly there are gaps in your raised bed. This is exactly the moment for one last round of direct sowing: radishes and Asian greens like mizuna actually do better in cooler nights than in midsummer heat. And because both grow fast, there is still something to harvest before the first hard frost.
Why late August works better than July
Radishes have a hard time in midsummer. Heat and long days push them into flower before they form a proper root, and what is left often tastes woody and unpleasantly sharp.
Now the balance shifts. Nights cool down, days get shorter, and the soil holds moisture longer. Those are exactly the conditions that make radishes tender and mild. The same goes for Asian greens: mizuna and pak choi germinate far more evenly in late summer than they do in July.
Radishes: about four weeks to harvest
Radishes are the fastest crop in your bed. Roughly 30 days pass between sowing and harvest, and you can keep sowing into September. So what you put in the ground in late August lands on your plate between late September and early October.
Sow the seeds about one centimetre deep, spacing them roughly four centimetres apart in the row. Sown too densely, they produce leaves instead of roots - the single most common reason for disappointed faces. The first seedlings appear after about a week.
Even moisture is the key factor. If the soil swings between bone dry and soaking wet, the roots split or turn woody.
Mizuna and pak choi: the fast Asian greens
Mizuna is a finely serrated leafy green with a mild mustard note and needs around 40 days. Pak choi, with its crisp white stems, takes about 45. Both can still be direct sown in late August.
Give mizuna roughly 20 centimetres of space, pak choi closer to 25. If you only want tender baby leaves, sow more densely and harvest earlier. Mizuna has one nice advantage: cut the outer leaves and the heart keeps growing, so a single plant gives you several harvests.
Both handle cool nights well, but neither is reliably frost hardy. Keep some fleece within reach once the first night frosts are forecast. Radishes, on the other hand, shrug off light frost without any trouble.
The mistake that happens easily: three brassicas in a row
Radishes, mizuna and pak choi all belong to the same family, the brassicas. Growing them side by side is not a problem - they get along fine as neighbours.
The tricky part is what came before. If that bed already held kohlrabi, rocket or an earlier round of radishes this season, do not follow up with another member of the same family. They draw on the same nutrients, and soil-borne diseases such as clubroot build up over the years. A rule of thumb: leave several years between brassica crops on the same patch.
Beds that just finished with beans, peas or zucchini are the better choice. After legumes, the soil is in particularly good shape.
Tiny holes in the leaves? Those are flea beetles
If the seed leaves of your radishes look like someone poked them with a needle, flea beetles have been at work. The tiny beetles jump away the moment you come close, and they love exactly what late summer offers: a warm, dry soil surface.
The most effective countermeasure is surprisingly simple - keep the surface of the soil moist. Flea beetles are far less comfortable on damp ground, and the seedlings grow out of the vulnerable stage faster.
If you want to be sure, lay a fine mesh crop cover over the bed right after sowing and weigh the edges down all the way around. One gap is all it takes for the beetles to get underneath.
Why this round is especially worthwhile with kids
Radish seeds are big enough for small fingers, and the first seedlings show up within days. For children that is a completely different time frame than pumpkin or carrot - the link between sowing and harvesting finally becomes visible.
A nice little routine: each child gets their own row and a label with the sowing date. Working out when harvest day will be is a reliable way to get everyone checking the bed more often.
In Rootivo you add the sowing to your bed with a single tap, and the bed planner immediately shows you which neighbours fit and when the harvest is due. What you note down this year will help you make exactly the same decision next late summer.
Im Lexikon: Radieschen