Gadenin日本語Get the appA shallow tray on a windowsill is enough
Pea shoots are one of the few crops that genuinely finish indoors. The seed carries almost all the food the shoot needs, so the plant is not depending on a deep root run or on fertile compost. An inch and a half to two inches (4 to 5 cm) of compost in a tray with drainage holes will carry a crop from sowing to the second cut, and the whole thing sits on a windowsill in a footprint the size of a baking sheet.
Depth beyond about three inches (8 cm) buys you nothing indoors. What it does buy you outdoors is buffering: a deeper pot or a band in the ground dries out more slowly and stays cooler, which matters once daytime temperatures climb.
Give the tray the brightest window you have. A bright east or north-facing sill in the northern hemisphere, or the equivalent shaded-but-bright aspect wherever you are, is better than a hot south window in summer, because heat is the thing that ruins the flavor. What you are looking for is light without a lot of direct midday sun.
Stretched, pale shoots mean light, not water
The commonest failure indoors is a tray of shoots four inches tall with stems like thread, pale yellow-green, leaning hard in one direction and collapsing under their own weight. That is not hunger and it is not thirst. It is light, and it usually starts in the first three days after you take the cover off.
Uncover the tray the moment the loops of the first shoots break the surface, not when they are an inch tall. Then turn the tray a half turn every day so the stand grows up rather than sideways. A stand growing evenly upright stays self-supporting; one leaning at forty-five degrees will fold over and start rotting where the stems touch the compost.
If the shoots are already stretched, you cannot fix that batch, but you can still eat it. Cut it slightly earlier than you planned, before the weight brings it down, and sow the next tray somewhere brighter.
| What you see | Cause | What to do |
|---|---|---|
| Thin pale stems, wide gaps between leaves | Not enough light, or covered too long | Brighter position, uncover at first emergence |
| Stand leaning hard one way | Light from one side only | Turn the tray daily from day one |
| White fuzz at the base of the stems | Wet surface and no air movement | Water from below, open a window, cut sooner |
| Tips wilting by afternoon | Tray drying out, or sun too direct | Water more often, move out of midday sun |
| Leaves turning tough with a bitter edge | Too warm, or the crop is past its cut | Cut it all now and sow again somewhere cooler |
Water from below and keep the surface dry
The stems of a densely sown tray are packed together with almost no air moving between them, and any water sitting on the compost surface goes straight into rot at the collar. Stand the tray in a shallow dish of water for ten minutes and let it take up what it needs from underneath, then tip out what is left. Do that every day or two, judging by weight rather than by looking at the surface.
A tray at this seed density drinks a surprising amount once the shoots are two inches tall, because the leaf area is enormous relative to the compost volume. A tray that felt fine yesterday morning can be bone dry by the following afternoon in a warm room. Lift one corner: a light tray needs water, a heavy one does not.
If you have to water from above, do it in the morning so the surface dries before nightfall, and pour along the edge rather than over the crop.
Never leave the tray standing in water. Peas at this density have shallow roots in a small volume of compost, and a permanently saturated base kills the stand from the bottom up in about two days, usually just before the first cut.
Skip the fertilizer, and keep it cool
There is no point feeding a crop you are cutting fourteen days after sowing. The seed reserve carries the first cut outright, and fresh compost carries the second. Liquid feed on shoots this young mostly produces soft growth that goes limp in the salad bowl, and in a tray with no drainage to speak of it builds up as salt.
Temperature is worth far more attention than nutrition. Pea shoots are sweetest and most tender between 55F and 70F (13C and 21C). Above about 77F (25C) the stems become stringy, the leaves take on a bitter edge, and the plant hurries towards making tendrils and flower buds instead of soft leaf. A cool room or a shaded outdoor bench in summer will produce a better crop than a warm bright greenhouse.
Keep a note of the room or bench temperature alongside the sowing date, and of how many days elapsed before you cut. Over a few sowings you will see the pattern clearly: the warm-weather trays reach cutting size sooner and taste worse, and that tells you exactly which weeks of the year to move the trays somewhere cooler.