Gadenin日本語Get the appThe shape of the gladiolus year
Gladiolus grows in one continuous push through the warm half of the year and rests dry through the cold half. Nothing about it is complicated, but the stages have to run in order and each one has a point at which a decision has to be made. Read the table as a sequence rather than a set of months, since the whole cycle shifts with the length of your growing season.
The usable constant is the interval from planting to first flower: roughly seventy to ninety days, shorter for small corms and warm soil, longer for large corms and a cool start. Everything else in the calendar can be planned around that figure once you have measured it in your own garden.
| Stage | Roughly how long | What you do | The decision that matters |
|---|---|---|---|
| Planting | Spread over 6-8 weeks in batches | Corms 4-6 in (10-15 cm) deep, 6 in (15 cm) apart, stakes in with them | Is the soil above 55F (13C) and frost past |
| Emergence | 2-3 weeks | Little or no watering, keep weeds down | Resisting the urge to water bare soil |
| First to fourth leaf | 3-4 weeks | Water in dry spells, mulch, first tie at 12 in (30 cm) | Getting support in before it is needed |
| Fifth leaf, spike forming | 1-2 weeks | Never let it dry out, start high-potassium feed | This is when spike size is decided |
| Spike emerging | 2-3 weeks | Steady water, second tie below the buds, ridge the base | Tie before the florets open, not after |
| Flowering and cutting | 1-2 weeks per spike | Cut when the lowest floret shows color, leave four leaves | How much foliage you take with the spike |
| Building the corm | 4-6 weeks | Keep watering and feeding while leaves are green | Not tidying the foliage away early |
| Yellowing and lifting | 2-3 weeks | Reduce water, lift on a dry day, cut stems short | Waiting for the leaves to yellow first |
| Curing | 2-3 weeks | Single layer, warm, airy, 75-85F (24-29C) | Curing hard enough that the old corm snaps off |
| Winter storage | Until planting | Paper or mesh at 35-45F (2-7C), dark and dry | Cold enough to stop thrips breeding |
Spreading the season with staggered plantings
Left as a single planting, gladiolus gives about ten days of flowers and then the bed is green leaves for the rest of the summer. Because the planting-to-flower interval is so consistent, splitting the corms into three or four batches planted a fortnight apart turns that ten days into six weeks or more of cutting, from the same corms and the same ground.
Start the first batch as soon as the soil reaches 55F (13C) and frost is past, then plant a batch every fortnight. Keep the waiting corms cool, dry and dark so they do not sprout in the bag. Stop planting twelve weeks before your expected first autumn frost: the last batch has to flower and then hold green leaf for four to six weeks afterwards, and a spike caught in bud by frost costs you the corm as well as the flower.
Expect the flowering intervals to compress. Later batches grow in warmer soil and catch up slightly, so four plantings at fortnightly intervals usually flower at intervals of ten to twelve days. Plan the last planting date around the frost rather than around a neat number of batches.
The five decisions that decide the season
Gladiolus asks very little week to week. What it has is a handful of moments where the choice made is difficult or impossible to reverse later, and nearly every disappointing season traces back to one of them.
- How deep the corms went Four to six inches (10-15 cm) over a full-size corm. This is decided in five minutes at planting and determines whether the spikes stand or lever themselves out of the ground in the first storm. It cannot be corrected afterwards.
- Whether the stake went in at planting A cane pushed in beside the corm at planting is trivial; a cane driven in next to a three-foot (90 cm) plant spears roots and is often too late. The support has to reach two thirds of the final height.
- Water at the fifth leaf The spike forms inside the plant at around the fifth leaf. A drought at that moment gives a short spike with few florets, and no amount of watering afterwards adds them back.
- How much foliage you cut with the spike Leave at least four leaves on the plant. Spikes cut with most of the foliage attached produce a corm too small to flower the following year, which is the usual reason a planting fades after its first season.
- How cold the corms are stored Cure warm for two to three weeks, then store at 35-45F (2-7C). Cold storage stops gladiolus thrips breeding on the corms over winter, which is what prevents the pest arriving with the corms next spring.
Three of these five cost nothing but timing: the depth, the stake and the four leaves. They are decided in moments that do not feel important, weeks or months before the consequence shows.
Turning the general calendar into your own
The stages above are a frame; the dates that make it useful are yours. Record the planting date of each batch, the date the fifth leaf appeared, the date the spike became visible, the first cut, the date the leaves yellowed and the date you lifted. After a single season you will know your own planting-to-flower interval to within a few days, and after two you can plant a batch to flower in a chosen week.
Alongside the dates, keep the counts: corms planted per batch, spikes cut, flowering-size corms lifted, cormels saved and corms discarded. The count that matters most is the last comparison, corms in against good corms out. A planting that returns more than it started with is self-sustaining, and one that returns fewer is telling you exactly where the season went wrong, since the only candidates are cutting too much foliage, stopping the feed after flowering, or lifting before the leaves had finished.