How to Store Tulip Bulbs Over Summer

Tulip bulbs lifted in early summer need to spend the next three to four months in dry storage before being replanted in autumn. Getting the storage conditions right determines whether those bulbs arrive at planting time firm, healthy and ready to perform, or shrivelled, mouldy and useless. The principles are simple — warm, dry, dark and well-ventilated — but the details matter more than most gardeners realise.

Drying Before Storage

Immediately after lifting, spread bulbs in a single layer on a tray, old newspaper or a slatted shelf in a dry, airy location — a shed, garage or well-ventilated greenhouse bench. Leave them for one to two weeks to allow the outer scales to firm and any surface moisture to evaporate. Avoid direct sunlight during this initial drying period, as intense heat can desiccate bulbs too quickly. Turn bulbs occasionally to ensure even drying on all sides.

Sorting and Labelling

Once dry, sort bulbs by size. Large, firm replacement bulbs (the primary bulb produced this season) should be stored separately from offsets. Label each batch by variety — bulbs look remarkably similar once their outer skin dries and the label from the original planting will long since have faded. Remove the dried roots and any loose outer scales (the thin brown papery skin), which can harbour fungal spores. Discard any bulbs that are soft, shrivelled, show brown internal discolouration when pressed, or have a musty smell.

Ideal Storage Conditions

The ideal storage environment for tulip bulbs is cool (15–20 °C), dry, dark and well-ventilated. This combination keeps the bulb metabolically quiet without allowing heat or humidity to encourage mould or premature sprouting. A cool, dry shed, garage or cellar is ideal. Avoid garden rooms or south-facing outbuildings that overheat in summer — temperatures above 25 °C reduce flowering quality by interfering with flower embryo development inside the bulb.

Storage Containers

Paper bags, mesh bags (the type that onions come in), wooden crates lined with newspaper, or cardboard boxes with ventilation holes all work well. Never use plastic bags or sealed containers — they trap moisture and lead to Penicillium (blue mould) or bacterial rot. Arrange bulbs in a single layer where possible, or at most two to three layers deep with newspaper between each layer to allow air circulation. Check stored bulbs monthly and remove any that have developed soft spots or mould, as rot spreads quickly from bulb to bulb in contact.

Optional Treatment Before Storage

Dusting bulbs with sulphur powder or a proprietary bulb fungicide before storage provides additional protection against Penicillium and Botrytis in storage. Shake bulbs in a small quantity of sulphur dust in a paper bag until evenly coated. This is particularly worthwhile in humid climates or if the previous season produced any disease problems.